Miller Ureys Origin of Life

Primordial Soup
    The primordial soup theory is to express a hot and fresh beginning of life.  Oxygen and certain organic compounds determine the basis for environmental factors relating to evolution.  Once these are in place, the component to trigger molecular structure is the use of intense heat.  It was argued that in the beginning of the earths atmosphere the conditions were such that creation of spontaneous life came in the form of the building of amino acids in an aquatic environment.  It was felt that this was a routine occurrence and responsible for the origin of the species (Tripod, 2010). 

    In 1920s a Russian and English theorist, Oparin and Haldane conducted an experiment to confirm that the first organisms were heterotrophs, which consumed other living matter to survive.  This would change with photosynthesis, and ultimately would evolve to autotrophs by mutation (Tripod, 2010).  Back then, the experiment was scoffed at, but today it is clear that they were onto something, as it is now known that the first organisms were autotrophs.  Urey and Miller wherein they reenacted the earths early atmosphere tested this theory.  The results were affirmative in light of the ability to create molecular structures of living organisms. 

Stanley L. Miller and Harold C. Urey
    The experiment of the two theorists Urey and Miller consisted of a mixing of gases thought to be present on earths atmosphere during its primitive stages.  They used Methane, Ammonia, Water, and Hydrogen.  The experiment did not include the use of oxygen.  To this mixture, they applied an electrical current in place of lightning conditions. The experiment produced amino acids.  The equipment used to reenact the experiment is as follows
A vacuum line
Spark electrodes  high voltage
Trap for prevention of any backflow
Boiled water in a flask to collect reaction products
Used a sealed tube to collect reaction products

These were the flaws with the Miller-Urey experiment
They believed the earths atmosphere contained ammonia, water, hydrogen, and    methane.
Oxygenation was present on the earths atmosphere, evidenced by the rocks found there, and that would indicate that chemical evolution would not have been possible.
They predicted the incorrect gas mixture

The results were not as specified the amino acids did not contain protein
    Due to the resulting ineffectiveness of the experiment, and proven fact that the hypothesis assumptive nature fell through in light of the findings, theorists and scientists agreeably discredited the Miller-Urey experiment.  Theorists and scientists started looking at other answers that had a feasibility factor regarding the earths oxygenated atmosphere and chemical compounds.  In looking for an alternative answer, one that stood out clearly was that the beginning of life occurred beneath the ocean floor in a volcanic environment.

Critical Evaluations of the Experiment
Other theorists in realizing that Urey and Millers interpretation of the earths atmosphere in its early stages was pure assumption and the basis of their experiments were strictly controlled challenged the experiments findings.  Therefore, their findings were not factual as to the true nature of the creation of molecular stimuli.  It has been proven that the creation of amino acids alone do not produce the amount of proteins necessary to provide the structure needed to support life.  Most importantly, the earths atmosphere did not contain Methane or Ammonia and studies show that for most of its existence earth contained an oxidized environment.  Further experiments using electricity, ultraviolet light, heat and shock resulted in the creation of all 20 amino acids (Tripod, 2010).

The thermodynamics in light of this did not support the findings in establishing that the system becomes less and less organized over time, which means that amino acids cannot form protein spontaneously (Tripod, 2010).  The resulting factors present that this translates into the dilution of the primordial soup.  Its consistency was too weak to have generated proteins, and there was no proof of the presence of a lightning environment to trigger the concentration to make protein (Tripod, 2010).

    Theorist and scientist, Wachtershauser, offers another view or explanation of the creation of the species.  He proposes that evolution occurred as a volcanic hydrothermal eruption, which manifested into a pioneering organism.  It consisted of a mineral base with catalytic transition born of a composite structure with metal centers.  The metal centers were thought to be along the line of iron and nickel, but could also be a mix of cobalt, manganese, tungsten, and zinc (Wikipedia, 2010).  His results were taken into account as they related to the autotrophs thought to be the first originating organisms. 

    The premise of the catalytic transition was simple and was supported by the process, which is construed as the heating and pressurizing of water in a mix of dissolved volcanic gases with the heat reaching 100C. At this point, the mixture then meets metal solids, and the result is the formation of catalytic metallo-peptides (Wikipedia, 2010).  Experiments to this effect and their findings support Wachtershausers theory.    

    Wchtershuser had a main idea that metabolism in its early form came before the existence of genetics, as we know them today.  The metabolic cycle produces energy from chemical reactions that show this process is replicative.  With replication, more advanced complex compounds were formed because of this process.  Wachtershauser modeled his interpretation of metabolic structure over prebiotic function, introducing it as the Iron-Sulfer World Theory. The concept goes in alignment with the RNA world hypothesis.

    Looking at an added factor is that of the RNA World hypothesis.  It specifies that gene pools of RNA existed in the early origin of earth, yet there was not any genes consisting of DNA.  Of course, this development drove theorists on a rigid mission to discover how DNA molecules were formed.  The belief is that the RNA has the capability of not only storing molecular structure but of also having the ability to create molecular structure by causing chemical reactions.  Thus, RNA acting as an intermediate in the expression of maintenance of the genetic information is the basis of the creation of DNA (Nobel, 2010).

    The storing of gene information is the resulting chains that link ancestry in defining how far back a species originated and to what specific gene pool it originated from. Through all of this testing much has been confirmed regarding RNA and DNA principles, but still there is not definitive proof that man evolved from the ocean, as did the many species existing in the world today. 

    Chemical actions and reactions, metabolism, metals, gases and more are a basic makeup, not excluding that we are electrically stimulated into animation.  The recipe presented by the many theorists and scientists are true in representing the foundation of man, however the ability to reproduce this recipe from an earthly standpoint has not yet been 100 percent successful.

    Todays scientists are now dwelling on the fact that the recipe can be duplicated in an environment with internal factors, vs. the external reenactment of earths atmosphere.  This is seen in the breakthrough of conditions that started as producing life in a laboratory in a peach tree dish, to the creation of life as a test tube experiment, and now the most exciting breakthrough of all the creation of life by cloning (Fisher, 2008).  A direct process using the living cells of a live host, and duplicating them to reproduce this host as a living breathing identical character of the original host.

    This type of experiment has not been thoroughly studied, and a cause for caution is warranted.  This has resulted in limitations and restrictions being imposed upon scientists that negate their use of humans in replicating DNA structures.  It is hard to believe that scientists would settle for not being able to explore this type of experiment on a human scale.  As time continues to pass, and new technology appears on the horizon, it would not be a surprise to see the event of cloning as a natural practice to defeat sickness and death, as man comes into an age of settling the controversy that has long been a question of evolution.  Although humankind may not be able to confirm that man evolved from earths atmosphere, he may settle for being able to copy life as it is in its existence and to be what he believes as holding the power to determine its quality of life and its time of demise.  The finding of the research that has gone before sheds light on earths atmospheric chambers yet still does not yield conclusive evidence in the creation of man. Confirmation that other species have evolved is evident in light of their findings yet, humankinds beginnings are still hypothetical in nature. What the research has shown is how fragile is the balance of earth and the surrounding universe in regard to mankinds existence, yet and still, how powerful in combination of each other in the ability to cause mans destruction.

Cancer Gene Therapy

The replacement of a faulty or absent gene with one that functions is referred to as human gene therapy. This therapy enables the body to produce the correct protein or enzyme which in turn eliminates the causes of the disease. Gene therapy can be either germ- line or somatic cell therapy. The latter corrects a malfunctioning or absent gene through cell treatment whereas the former treats an embryo or gamete used in vitro fertilization.

Most of the earlier attempts to bolster the response of the immune system to cancer have not been successful. However with the gene therapy researchers have hinted at some success. There are a number of advantages to this therapy such as prevention of some of the serious illnesses, treatment of the gravely ill and the fact that the therapy primarily tackles the cause of the disease as opposed to its symptoms. These merits however do not blind us from the numerous shortcomings that are likely to plague the society once the gene therapy is fully adopted.

Arguments against Gene Therapy
Gene therapy is a new treatment and the long term effects on the patients have not been established. This means that a continued surveillance of the patients will be required in order to curb long- term effects. It is important that the future generation be safe otherwise it might lead to further complications. There is still too much uncertainty more so regarding germ-line therapy.  It is true more that one type of cell can be infected by a virus.  In this way both healthy and cancer cells can be infected when genes are carried in the body by viral vectors. In addition the risk of improper insertion of the new gene can cause mutations.

The germ-line gene therapy has a provision to carryout research on embryos. This research is done without the consent of the subjects. Furthermore the research is likely to hinder their offspring. It is therefore unethical for such experimentation to be done on subjects without their consent.

There are also fears that gene therapy will be an opening for researchers to try and alter some human traits that are not necessarily linked to the disease. The likely result is increased discrimination in the society. Also referred to as genetic apartheid, the trend will see to a small percentage of privileged few in the society benefiting from synthetic genes. This will further increase inequality in the society.
Again, it is very expensive to carryout a gene therapy. Already the existing therapies are rather farfetched for the common man. This new gene therapy will only be affordable for a few. There will be much pressure for governments and organizations to cater for the cost. In truth there are a number of priorities in society other than investing in the therapy. Similarly, though expensive its applicability is limited. Genetic defects are detected in a small number of live births (2). The meager resources channeled in this project might as well be invested in alternative heath programs.

The rights of subsequent generations will also be violated with the institution of the germ-line therapy. Since the therapy intentionally modifies the genetic make-up of the patients then future generation will inherit distorted genes. This process is irreversible thus a good reason to be skeptical. As pointed early the long term effects are not known yet. It is therefore a violation of their rights.
Furthermore, the medical fraternity will also face too much pressure to see to the use of the germ-line therapy for enhancement. For instance there are individuals who despite not suffering from dwarfism will want to enhance their height. As much as the hormone is important it will not be used for its intended purpose. Initially it was meant to address forms of dwarfism. It is however likely that the therapy might never be used for its intended purpose.

As much as the gene therapy has some merits there is still much research to be done in order to eliminate the risks and alleviate some of the fears. Already there are some cures for cancer. Though they have not recorded 100 per cent success, these cures should be improved on before introducing another therapy. Again, it is not proper for humans to be used as subjects of experimentation without consent. This not only exposes the society to risks but violates the rights of an individual. Further, the new gene therapy is expensive hence prudent for the money to be invested in other viable health programs. Already our contemporary society is faced with great inequalities. Introducing the therapy will mean further polarization and discrimination.

Finally, some of the process is irreversible hence the need for people to be careful before making a forward step.

Penguins and Climate Change

The word  penguin  means  fat one  in Portuguese and  White head  from the Welsh s  pen gwyn.  The term also originated from  pinguis  in Latin meaning  fat,  which was originally given to the Great Auk that was hunted down to extinction. Since the Great Auk and penguins share the same anatomy, they were mistaken as the same animal by the explorers that first saw them in the Antarctic Peninsula and thus, were given the same name ( Penguin Science  2010).

Penguins are a type of flightless birds belonging to the Sphenisciformes order that thrives in the Southern Hemisphere mainly in Antarctica (but there a few species known to be living in temperate zones such as the Galpagos penguins). Instead of having wings, which are the most distinctive characteristics of birds, penguins have paddle-like flippers and a streamlined body tapered at both ends which make them very agile in the water. When not in the sea, penguins use their short legs and tail to waddle or slide across snow on their bellies (Wolf, 2009).    Penguins are very sociable animals they like to hunt and feed in groups and stay in colonies while on land. Although penguins are known to feed on squids and fishes, their infants primarily eats krill (shrimp-like crustaceans) for sustenance until maturity where their diets can include varieties of fish, squids, and other crustaceans. During breeding seasons, penguins need land-lock, frozen, rocky areas for nesting. They usually nest in large colonies called rookeries where they sometimes amass to thousands ( Sea World Parks  2010).

    The penguins are greatly threatened by the continous rise in the world temperature, this is mainly attributed on the exponential increase of greenhouse emission in the atmosphere. For the last years, the earth surface temperature has been exponentially increasing, prompting the slow melting of the polar ice caps, the penguins  natural habitat. It has also greatly contributed to the depleting food source of the animals, resulting in starvation and death. The rapid decrease in the penguins  population can also be accounted for the lack of proper breeding and nesting grounds caused by excessive snowfall and the rise of sea water level.

    The graph below shows the increment of carbon dioxide concentration in the atmosphere and its forecasted increase until the year 2100, which was predominantly caused by the Industrial Revolution. Carbon dioxide is emitted in the burning of fossil fuels and it represents 80 percent of the greenhouse gases that are directly causing global warming.

On the other hand, the graph below represents the rise in temperature for the last 140 years. While the change may seem insignificant just a few degrees in the past years it is the consistent relative rise in the warming of the ocean waters that is directly responsible for the gradual deterioration of pack of ice and glaciers on the earth s ice caps.

     Krills, which get sustenance from deep sea algae found in the depths of the ice packs, are the staple food for most species of penguins. In fact, the diet of Adlie penguins, (Adlie are the most threaten by global warming because of the rapid decrease in krills population, they exclusively inhabit the Antarctic peninsula) is 99 krills. (Wolf,  2009) However, According to the World Climate Report the gradual melting of the ice caps because of global warming has led to the diminishing population of krills, since krill larvae require sea ice to survive. The acidification of sea waters also has a great impact on the proliferation of the sea algae, which are food for the krills. Since the oceans absorb a major portion of the greenhouse gases present in the atmosphere through the water cycle, carbon dioxide neutralizes the carbonate ion present in the sea water. Carbonate ion is important for the development for the outer shell (calcium base) among planktons, crabs, corals and other crustaceans . The acidification of the ocean can also cause a direct damage to the lives of penguins, it can cause poisoning which could lead to death. The continuous acidification of the ocean can be foreseen as one of the biggest threat to the survival of the penguins in the future. (Orr et al., 2005)

    Global warming also contributed to the diminishing breeding grounds for most penguins, the Emperor and Adlie penguins in particulars. The Emperor penguins need solid land-lock sea ice to rear their young until maturity or until the chicks have grown waterproof feathers. In cases where sea ice breaks before the chicks reach maturity, they are swept in the ocean where they will most likely die. Adlie penguins, on the other hand, build their nest on snow and ice free areas. However, because of excessive snowfall cause by the warm temperature (warm air can hold more moisture), it becomes nearly impossible for the penguins to find snow-free areas to lay their eggs. As a result, their reproduction becomes threatened (Wolf, 2009).

As for the penguins inhabiting the equatorial region of Galpagos Islands, desert coasts of Africa and South America, they solely depend on the movement of the cold nutrient rich sea water to bring food and sustenance. Thus, the occurrence of El Nio, a dry spell phenomenon caused by the disruption of the ocean-atmosphere system in the Tropical Pacific, prevents cold water from moving to the surface but instead forces warm water to move to river beds, and estuarine waters, which results in the starvation and death of penguins in this area. The Galpagos penguins have proven to be extremely vulnerable to starvation during El Nio events. Adults are forced to abandon their eggs and chicks to search for food, leaving their chicks to starve (Vargas, et al 2006).

    According to the year 2009 studies conducted by the World Wide Fund for Nature (WWF), a 2C increase in the world temperature can result in the elimination of at least 50 of the colonies of the emperor penguins and 75 of the Adlie penguins colonies. If the emission of greenhouse gases to the atmosphere continues at its current rate, it will take only 40 years to make the 2C rise in the world temperature a reality. The relative escalation of sea water temperature will result in the thinning of the ice caps and water level increase that will eliminate most of the breeding and feeding grounds for the penguins. The continuous introduction of carbon dioxide to the oceans will make their water corrosive from the surface to their depths (Bracegirdle, et al 2008). The sea ice will melt exponentially and all organism and animals dependent on this ecology will cease to exist.

    Global warming would also promote the frequency of the El Nio phenomenon that would threaten the survival of the penguins inhabiting the equatorial regions. There are also other eminent threats to the survival of penguins, the most dominant of which is industrial fishing which rapidly depletes the food supply of penguins. Other potential threats to the survival of penguins include marine pollution, human disturbance to their natural habitat, diseases, and direct harvest of eggs and birds (Wolf, 2009).
    If the current rate of global warming continous, the lives and habitants of the penguins will be greatly endangered. The topic discussed on the dimishing food supply of penguins and the effects of  the El Nio phenomenon are clear indications of the future that these magnificient animals will face if we dont change our ways. It should be the personal responsibility of each one us to make sure that we do all we can to preserve the lives the penguins. The government must also impose stricter laws on industries that contribute on the pollution of the environment.The onset of the industrial revolution marked the accelerated rate on the destruction of the environment, it is only proper that these industries must now  advocate the rehabilitation and preservation of the environment.


The muscular system is the system in the body that is primarily responsible for movement.  The muscular system does this primarily when individual muscles contract while attached to a series of lever and pulley systems which include the framework of the body or the skeleton on which muscles are attached via tendons, cartilage, and ligaments.  (Inner Body) It is consists of all the muscles in the body divided into two main categories, involuntary and voluntary muscles.  (Inner Body) This classification is according to how the human brain can consciously influence the movement of these muscles.  Muscles that cannot be influenced consciously are known as involuntary muscles (Inner Body) these include smooth muscle which is what most internal organs are made of and cardiac muscle or the muscle of the heart.  (Inner Body) Muscles that are consciously made to contract are known as voluntary muscles and this includes skeletal muscles which comprise about 40 of an adults body weight.  (Inner Body)

    As mentioned earlier, the muscular system is responsible primarily for movement.  Movement is achieved in the muscular system when muscles contract.  Contraction of muscle is normally characterized by an increase in tension along the body of the muscle as well as the shortening of the muscle.  However, there are cases where such does not occur (Inner Body)  in isometric contraction, the tension in the muscle increases but the length does not change  an example of this kind of contraction is when we attempt to push against an immovable wall or we try to tense the muscles of our neck.  The muscular system serves three primary functions these are movement, posture and muscle tone, and heat preservation.  (Inner Body) Of these three primary functions, the first is the most common.  The muscular system enables us to do certain things like move our fingers, walk, clench our fists, move our jaws, and many other movements that are a result of muscle pulling against the bone to which it is inserted.  In terms of posture and muscle tone, some muscles serve to keep up upright  these muscles are known as anti-gravity muscles and work overtime to keep the effects of gravity from affecting our bodies.  (Inner Body) Without the muscular system, we will all fall to the ground because of the effects of gravity.  Muscles keep our head upright, our back straight and maintaining proper posture, and our legs in the extended position to prop our entire weight up. 

Muscle tone, as a function, means that the muscular system gives our body shape.  (Inner Body) The muscles underneath our skin are responsible for the bulges on the arms of athletes or the shape of our buttocks.  Finally, as one other function of the muscular system, it enables us to keep heat within our bodies.  While this is a primary function of fat, muscles also contribute to this.  The human body is made up of many layers to pad the internal organs against the elements  the skin, fat, and then the muscles.  If the skin and the fat are not enough to keep body heat levels normal, the bodys next line of defense is the muscular system.  Other than just insulating or padding the body, muscles generate their own heat.  When muscles contract, energy is released, and this release of energy causes bursts of heat all throughout the body.  The functions mentioned are chiefly associated with skeletal muscle, (Inner Body) smooth muscle and cardiac muscle, on the other hand also have their own specific functions.  Cardiac muscle is responsible for the rhythm of the heart. (Inner Body)  The heart works 247 every single day of our lives to pump blood throughout the body.  This rhythmic movement of the heart is caused by the continuous and regular contractions of the cardiac muscle.  Smooth muscle also has a different function from skeletal and cardiac muscle smooth or visceral muscle is what makes up our internal organs like the bladder and the stomach (Inner Body) in the stomach for instance, it causes the digestive movement known as peristalsis, and in the bladder, it contracts when the organ is full to expel excess water known to us as urine.   

    The muscular system is a very important component of our biology and understanding how muscles work gives us a better concept of what makes our bodies tick.  As a result of this awareness, we become more conscious of our bodies and we begin to take more care of our bodies as much as we can.  Our health is dependent on how well we take care of our bodies and knowing more about our bodies only serve to enable us to take better care of it.

Prevention of global warming

Global warming is a weather phenomenon where the temperatures of the atmosphere near the surface of the earth have increased continuously in time. This is as a result of the increasing concentration of green house gases in the atmosphere resulting from both natural and human activities like volcanic eruption and forest fires.  As a global menace, it affects each and every human being and all sectors of the economy

Global warming results to a negative and a positive feedback mechanism to the dynamics of the atmosphere thus need to be well understood to avoid losses. The elite, being the policy consultants if not the leaders thus requires the knowledge for preparation of the policy papers expeditiously. More so the knowledge available should correlate with the atmospheric changes for proper planning (Lomborg 36). 

The atmosphere is the mother nature of all disciplines of life sciences. In effect, any variance in its composition in one way or the other directly or indirectly affects the other disciplines. Global warming has led to the speed up of the hydrological cycle. This has led to the intensification of desert areas, more severe and frequent flooding, reduction of ice caps in the mountains and also more ice thawing in the polar areas. Aviation industry heavily depends on the atmosphere as a medium of transport and the recent drastic changes in the atmospheric conditions leading to heavy icing leads to changes on the aircraft aerodynamics and this has led to great losses.  Thus, the transport industry had to advance in the crafting models to help curb this. (IPCC 564)

Entailing more than the average rising temperature  but also long term changes in precipitation amounts, high tide levels, ocean salinity and acidity, wind patterns and extreme weather events, including droughts, high precipitation, heat waves and the intensity of tropical cyclones, that entails  hurricanes and typhoons poses great danger and exposure to calamities. Scientists experience uncertainty due from the models that they use where some are outdated. This results to slower rate of adaptation as compared to the rate of atmospheric change. Also the theoretical frameworks available to understand the global climate change are not convenient thus leading to great losses in the business industry. There is the lack of casual link between the human knowledge and the climate change, whereby there are cases of conflicting information and predictions. Clear understanding of the global warming is vital, considering the most vulnerable people to the effects  including the low lying areas and coastal areas due to flooding as well as those living in the Arctic areas due to the melting of the polar ice will definitely lead to change of their way of life and the ecosystem. (Gardiner 555).

Global warming also leads to threats in the cultural heritage and the traditional ways of living including the feeding habits. The countries at great threat of effect and exposure have incurred political instability and drastic amendments of policies to avoid displacements of the citizens. Also, ill health of people, plants and animals have great threats to their wealth and their lives too.
There exists some strength in Science related to the global warming which includes the use of modern technology top help combat its effects. But, the limitations are also equally or outwitting. There exists a great shortage of data available on the science of climate change. The models used to interpret the data available to help in the formulation of climate predictive models are uncertain. (Lomborg 36)

This calls for strong prediction and interpretation models that should be adapted to help in the early warning. This is through the identification of the climate models gap and the updating of the current one more so on the extreme weather events. This helps the scientists to accurately advise the policy makers that would wisely notify the public instead of relying on the disaster management.

Type 2 Diabetes and Effects of Exercise

There are two types of diabetes that normally affects people. The first one is type 1 diabetes and is the most common especially among the young generation. This is caused by inability of the body to produce enough insulin. The second one is type 2 diabetes which is the main focus of this research paper, and is most prevalent among the older population. However in the recent past, more cases are being recorded for type 2 diabetes among the young adolescents. It is characterized by not only lack of enough insulin production, but also insulin resistance. The risk of developing type 2 diabetes in the adolescents has been further increased by the changing lifestyles. In the recent years, there has been a significant rise in consumption of fast foods. This has led to prevalence of obesity and thus the body requires higher amounts of insulin in offsetting the body demands for complete use of food for energy.

However, more complications have resulted due to decreased physical activities. In this era of Information technology, people have retreated to playing internet games and watching television as their means of spending time unlike in the past. Hence, the rapidly changing lifestyle to physical inactivity counts a lot. Mag  (2000). states that insulin resistance may also be induced by natural phenomenon such as pregnancy. Mostly type 2 diabetic patients are not treated by exogenous administration of insulin as it is mostly caused by obesity and physical inactivity. Although the genetic factor of the family counts, it counts to a little percentage. NAME states that eight percent of type 2 diabetic patients are obese land the disease may prevail for a long time without being noticed. For instance, Mag (2000) notes that in a study conducted by Mokdad from 1991to 1998 in the U.S., reported cases of obesity had gradually increased regardless of gender, race, sex, level of education, age, and the smoking of individuals. It was further found out that the percentage rate of increase in the same period ranged from 12.0 to 17.9.

Type 2 diabetes and exercise
Consequently, the hyperglycemic conditions of type 2 diabetes bring about micro- and macro- vascular complications especially to key organs of the body kidneys, eyes and heart. Persons with type 2 diabetes are more predisposed in developing cardiovascular diseases than those without. They mostly posses quite number of cardiovascular diseases risk factors and such include, hypertension, and dyslipidaemia (increased serum triglycerides and low contents of high density lipoprotein). However, a lot of regular exercises have been found to significantly reduce the risk for developing cardiovascular diseases through physiological and metabolic mechanisms (Mag, 2000).The health benefits accumulate proportionally to the intensity of the physical activity. NAME states that a remarkable dose-response relationship between the intensity of exercise and the improvements in the risk factors of cardiac diseases.

Physical Exercises in the Prevention of Type 2 Diabetes to in persons at risk

Appropriate life interventions physical activity and weigh loss- can possibly prevent and  or delay development of type 2 diabetes. Mag (2000) documents that certain life intervention study which was carried out on type 2 diabetes risk group. The life intervention program consisted of a weekly physical activity of at least 150 minutes and 7 loss in body weight. At the end of the study, the incidence of developing diabetes was found to decrease by at least 58 regardless of gender, race and age group. Besides, the study group demonstrated a significant decrease in glycosalated hemoglobin and they also found that during the three year treat period, one in every seven persons was prevented from developing the disease and its complications.

Physical exercises and Insulin Resistance

Regular physical activities have been found to have long term effects on the insulin sensitivity of the in a diabetic person. They improves and brings to normal levels both the insulin response and sensitivity for normal glucose utility in the body. Physical exercises compel the body to use excess glucose for muscular activity. These results in reduced plasma glucose levels and the conditions may prevail for a certain period of time if the physical exercises are continual. It has been found that sufficient time as well as intensity of the physical activities leads to prevention and or correction of physiological and biochemical changes of the body that is mostly common in sedentary life.

Physical activities deplete the body of its excess glycogen stores and thus increase insulin sensitivity. It does so by compensating the amounts of lost glycogen during the muscular activities. Therefore type 2 diabetic patients improve drastically the metabolic activity of their bodies (Ivy, 1997). According to Henriksen (2002) both acute and continual physical activities leads to improvement of insulin-initiated glucose metabolism especially in type 2 diabetic patients. Further studies by Segal et al. (1991) shows that constant exercise of can largely improve body metabolic activity in spite of weight reduction as earlier stated. Zierath and Henriksson H (1992) states that these recorded improvements in metabolic activity can be attributed to a decreased rate in peripheral insulin resistance andor increased insulin sensitivity that accompany physical exercises. In addition to physical activity, it has been observed that persons who maintain lean muscle and fat mass, experiences an increase in insulin resistance. Regular physical activities, in terms of time and intensity, results in reduced basal and glucose initiated insulin concentration in the circulatory system. Further, 26 states that there are significant increases in insulin-stimulated glucose consumption rates upon physical training.

Exercise and Dyslipidaemia

Continual physical activities are normally associated with remarkable effects on glucose control, contents of blood lipids, and functions of the heart and lung.  Zierath and Henriksson H (1992)  in thair work found that the effects of physical exercises draw a parallel with age of a person, whereas levels of lipid in the blood are dependent upon the body weight. Thompson et al. (quoted by Mag, 2000) documented that following sufficient physical exercise, triglyceride levels reduces within 18-24 hours and this condition is steady to induction of changes in metabolic activity which may persist for up to three days. Besides, they also found physical exercises to drastically increase the High Density Lipoprotein cholesterol levels. Thus, this parallel increase in High Density Cholesterol versus a reduction in triglyceride levels can be interlinked to the same metabolic activity. Mag, 2000 states that Low Density Lipoprotein levels decreases by at least 5-8 in persons with high level cholesterol content after physical exercises.
Physical Exercises and Endothelial Dysfunction

Research study has found out that to significantly decrease cardiovascular risk factors especially in type 2 diabetic patients. 17 in his research study on type 1 and type 2 diabetic patients found out that physical exercises rectifies metabolism besides the endothelial dysfunction factors  such as thrombomodulin,  vWF and PAI-1. Therefore it is possible that improvements in endothelial dysfunction factors may be correlated to the protection accorded by physical exercises on the endothelium.

Stewart (2002) writes that the coexistence of type 2 diabetes and high blood pressure is particularly damaging to the soundness of the vascular system. He states that most of the studies on the effects of physical exercises have been concentrated on reduction of regulation of glucose content and hypertension. Thus he further states that there is little known about the impact of physical exercises on cardiovascular consequences of type 2 diabetes 0on and hypertension. In the documented work of Stewart (2000), it is stated that,

Type 2 diabetes and hypertension result in abnormalities in central and peripheral parameters of cardiovascular structure and function. Evidence for an exercise training benefit is strongest for improvements in endothelial vasodilator function and left ventricular diastolic function. The data for exercise trainings improvement of arterial stiffness and system inflammation and reduction of left ventricular mass are less robust. However, this assertion is based more on a lack of randomized controlled trials rather than data to the contrary. Exercise training also reduces total and abdominal fat. These changes in body composition mediate improvements in insulin sensitivity and blood pressure and may improve endothelial vasodilator function. The current evidence, albeit not fully confirmed in randomized trials, suggests that the benefits of exercise training go beyond the recognized benefits of glycemic control and blood pressure reduction.

Programs of physical activity can be successfully implemented in school programs and at home especially for childrenadolescents so as to mitigate obesity(Carrier L  Herbert L, 2004).

Prokaryotes and Eukaryotes Cell Structures

The cell wall and flagellum are among the vital bacterial cell structures. A bacterial cell wall is a tough, normally flexible but sometimes fairly rigid layer which encloses the contents of bacterial cell. It is always located outside the cell membrane and is composed of murein materials. These materials are made of polysaccharide chains cross linked by atypical peptides encompassing D-amino acids. The cell wall allows the survival of bacterial cells as a unicellular organism by separating the interior contents of the bacteria from the environment. This protects the cell against harmful influences emanating from the surrounding. Additionally, flagellum is a rigid helical filament structure which extends from the surface of bacterial cell. It is composed of flagellin proteins that are arranged in helical chains forming a hollow core. Flagella facilitate motility of bacterial cells, thereby allowing them to respond to stimuli, such as chemicals and heat which they need for survival as unicellular organisms (Cells Alive, 2006).

On the other hand, mitochondria and chloroplast are essential organelles of the plant cell. Mitochondrion is an organelle that is membrane enclosed, found in many eukaryotic cells. It has outer and inner membranes composing of proteins and phospholipids bi-layers. Mitochondria in plants, just like in other eukaryotes, play an imperative function in the cell as the main producers of adenosine triphosphate through oxidative phosphorylation. The energy produced by this organelle augments the development process of plant cells, thereby enabling the survival of multicellular plants. Finally, chloroplasts are disc like organelle composed of biochemical systems as well as chlorophyll for light harvesting and photosynthesis. It is in the green pigment (chlorophyll), that the process of photosynthesis occurs the process that provides food to plants to enhance their survival as eukaryotes (Enchanted Learning, 2009).

Polycystic Kidney Disease

In normal cases, nephrons filter out wastes, excess substances, and fluids from the blood. However, in individuals with polycystic kidney disease, kidneys become enlarged with numerous clusters of cyst, which interfere with the normal renal function. This sometimes results in renal failure and thus, demanding for kidney transplant or dialysis. Besides, cysts may as well develop in other body organs, especially the liver and pancreas.

Polycystic kidney disease is a hereditary disorder and thus, the inheritance pattern is autosomal dominant. Since the disease occurs equally in both male and female, each offspring encompasses a fifty percent probability of inheriting the affected chromosome and therefore, the disease. In approximately ninety percent of these cases, an affected individual inherits the defect gene or mutation from either one or both parents. Only ten percent of these cases emanate from novel mutations in one of the genes and take place in persons without any history of the disorder in family.

Frequent signs and symptoms associated with polycystic kidney disease include hypertension, back pains, blood in urine, kidney stones, heart valve abnormalities, frequent urination, and recurrent urinary tract infections. Additionally, individual with this kidney disease have an escalated danger of an abnormal bulging of aorta or other blood vessels. At this moment there is no definite treatment for this deadly disorder. However, it is important, vital, and essential for any person with this disorder to have regular medical checkups. Treatment is heavily limited to complications, such as hypertension, infection, and kidney stones. Intake of low protein and fat diet may as well slow the disease progress.

Summary of a Scientific Article

It has been established that disease causing micro-organisms may acquire resistance to the antibiotics like penicillin through the exchange of the DNA with the risk-free bacteria that resides in the human gut. In effect, the antibiotics may not be effective on the antibiotics-resistance genes.
This paper would summarize the functional characterization of the Antibiotic Resistance Reservoir in the Human Micro-flora as presented in a study by Morten O. A. Sommer, Gautam Dantas, and George M. Church.

In the past few decades, multiple antibiotic resistances have been discovered posing a great challenge on the treatment of bacterial infections. Whole-genome sequences of the bacteria has indicated that most of the resistance genes affected by these strains did not evolve in the sequenced strain but instead they were gotten from lateral gene transfer events, (Sommer, Dantas,  Church, Para 1). The human micro-biome has a substantial impact on the health of individual playing crucial roles in the digestion process and in prevention of pathogenic intrusion. Sommer, Dantas,  Church conducted a research to establish the existence of resistance genes in the gut bacteria. The research used samples from the feces and saliva from two healthy individuals allowing the bacteria to develop in environments with common antibiotics. The bacteria were found to exchange the genetic makeup between them suggesting that resistance can also be transferable. A small sub-set of bacteria in the elementary canal was found to harbor resistance genes similar to those found in the pathogens (Lee, Para 8).

Though some of the bacteria were found to be able to transfer genes between themselves, scientists are yet to find hard evidence on the allegation that harmless bacteria found in the gut can pass the antibiotic resistance to pathogens. However, revelation that increased use of antibiotics as medicine and in agricultural practices is likely to induce significant responsive alterations in the DNA of the micro-biomes is something worthy pondering about.

Why There Would Be No People without Plants

Animals and plants are living things that depend with each other for survival. Plants manufacture their food through photosynthesis while animals depend on plants for their food. In order for plants to manufacture food, they require carbon dioxide, sunlight and water, (Silverstein, Silverstein  Nunn, 2007). This paper shall therefore describe the process of photosynthesis and how animals benefit from the process of photosynthesis and also demonstrate that without plants, animals including human beings cannot survive.

Background Information
    Photosynthesis is a process through which plants manufacture their own food by use of carbon dioxide, energy from the sun and water. According to Rao  Hall (1999), the process of photosynthesis occurs in the chloroplasts. Chloroplasts contain chlorophyll which is able to take the energy from the sun. Carbon dioxide combines with water and in the presence of sunlight plants manufacture carbohydrates and also release oxygen.

However, carbohydrates need to be further broken down through a process of cellular respiration in order to form energy that can be used by plants. This takes place in the cell mitochondria in the presence of oxygen. The products of this process are water, carbon dioxide and energy.  On the other hand, animals depend on oxygen gas and carbohydrates for survival. During respiration, animals take in oxygen and release carbon dioxide while plants take in carbon dioxide and release oxygen.

How People Benefit from Plants
As indicated by Rao  Hall (1999), animals do not make their own food. They depend mainly on carbohydrates manufactured by plants in the process of photosynthesis. Animals require this energy to carry out their activities in the body. Oxygen released by plants during the process of photosynthesis is also a vital gas for the survival of animals. Moreover, plants purify the air as they take in carbon dioxide that is released by animals during respiration. Rao  Hall (1999) continue to argue that, were it not for the process of photosynthesis, the atmospheric oxygen can be used up in a period of three thousand years. Therefore, one of the most important functions of photosynthesis is to balance the amount of carbon dioxide, and oxygen in the atmosphere.

Failure of plants to release enough oxygen to the atmosphere is a dangerous phenomenon. It results in excessive carbon dioxide in to the atmosphere. This case was clearly illustrated in the biosphere experiment.  During this experiment, as Day (2005) records, the level of oxygen decreased while the level of carbon dioxide increased. The continued use of oxygen led to its reduction while carbon dioxide released by people during respiration greatly increased in the air. The condition could not be tolerated by people and more oxygen had to be pumped in while air purifiers were used to remove excess carbon dioxide.

    Plants and animals depend on each other for survival. Even with all the conditions needed for survival, none can survive for a very long time without the other. In the case of animals, this was clearly shown in the biosphere experiment in which even before the end of two years, there was so much carbon dioxide in the atmosphere and air purifiers had to be used. Oxygen level in the air went down and more of it had to be pumped in. Likewise, plants cannot survive in an air tight container that has everything expect oxygen. This is mainly because the oxygen released during photosynthesis may increase and interfere with the rate of photosynthesis. Moreover, oxygen is used during the process of cellular respiration by plants.

From this paper, one can conclude that without plants people cannot survive. This is because everything needed by people for survival is primarily from plants. This includes the food as well as the oxygen.

Answers to Some Biology Questions

For the first question, the group can procure living things for study by taking note of the hallmarks of life. According to Starr, Evers and Starr (2008), living things share the following characteristics in common (1) they are capable of utilizing an energy source and materials from its environment to build itself up and grow (2) they can adapt to changes in its environment via long-term evolution or an immediate response, for the purpose of its survival and for regulating its functions (3) they are capable of producing new things like itself and (4) they exhibit a definite structural organization.

    These characteristics are all present in a lot of organisms commonly found in our environment. These characteristics are not universal, however for instance, debates are still on-going as to whether viruses are alive, in spite of their inability to meet condition 1 when theyre not infecting cells, and some non-living things like artificial membranes are shown in the laboratory to meet condition 4. But for purposes of a collection the presence of even one characteristic should be sufficient ground for us to collect a sample for studying.

    For the second question, the gain or loss of subatomic particles such as electrons, protons, and neutrons give rise to different conditions that follow a number of conservation principles. Of the three particles, only the loss and gain of an electron is observable in common natural processes. In chemistry, the gain and loss of an electron occurs simultaneously between two atoms, resulting in the formation of a chemical bond. The transfer of electrons from one region to another gives rise to an electrical charge, as is the case with the electrical charge produced when rubbing a wool cloth on a glass rod.

    The gaining or losing of either a proton or neutron does not occur outside the realm of radioactivity, and not without the input of tremendous amount of energy. The loss or gain of a proton changes the identity of the atom into that of another element, as well as change the electrical and other properties of the resulting particle or particles. The loss or gain of a neutron produces an isotope of the element to which the atom is classified as.

    For the third question, the complexity and sheer amount of activity the parts of the cell can do, the cell can be compared to a city. For instance, the endoplasmic reticulum (ER) can be seen as a sort of cellular factory, which produces both materials like lipids in smooth ER necessary to making the cell membrane, as well as the workers themselves, called proteins, in rough ER. The cytoplasm can be seen as the citys whole transportation system, as it transports food, electrolytes and other substances throughout the cell as well as outside it, with the use of appendages on the cell membrane.

    Molecules used other than for structural purposes can also be seen in this light. Still using this analogy of the cell as a miniature city, the DNA comprises the citys laws, while RNA and all the machinery for protein synthesis are law enforcers, making sure that the instructions encoded in DNA are realized. The products of this machinery, called proteins, are in turn the workers that run this machinery as well as all the processes occurring in the cell.

    The complex substances called enzymes are proteins. For the fourth question, enzymes function to facilitate the chemical reactions within the cell. Basically, enzymes prepare its target molecules to make it easier to react with before it is converted to products. Without enzymes, the reactions would occur slowly, as it is hard to convert most common molecules into new ones.

    For instance, the conversion of food sugars (say, glucose) into a usable energy source for the cell in the process called metabolism is a chemical reaction wherein the glucose reacts with oxygen to produce carbon dioxide and water. If this reaction were to take place without enzymes, the reaction would take hundreds of years to complete, while in human cells this take place in seconds, allowing for a constant supply of energy that can be utilized.

    Finally, for the fifth question, the processes called metabolism and photosynthesis are complementary cellular processes, which use raw material from the earth and energy in the form of sunlight to sustain life on earth.

    As discussed in the previous question, carbon dioxide is a by-product of metabolism by animals and other creatures using the same mechanism for energy production. This carbon dioxide is taken in by plants and other photosynthetic organisms. Carbon dioxide will then combine with water and using the energy from sunlight to produce glucose, which also serves as its energy source, and oxygen as its by-product. This oxygen is released to the environment, to be taken up by animals and their kin, and this self-sustaining cycle continues on.


Hepatitis B virus is a member of the Hepadnaviridae. The hepadnaviridae has been known to cause a liver disease, known as hepatitis, in several animal species. HBV is a DNA virus. The intact virus is a spherical, double-layered Dane particle that has an outer surface envelope of protein, lipid and carbohydrate enclosing a slightly hexagonal core (Kumar, Abbas,  Fausto, 2008). HBV is a relatively large virus with a diameter of 42nm. It has an enveloped icosahedral capsid and double stranded circular DNA. Under the electron microscope, the icosahedral capsid is seen to be studded with protein spikes and the double stranded DNA is associated with a DNA polymerase enzyme. The organization of the HBV genome is unique in that all regions of the viral genome encode protein sequences

A nucleocapsid core protein (HBcAg) and a longer polypeptide transcript with a pre-core and core region, designated (HBeAg)

Envelope glycoprotein (HBsAg)  Infected hepatocytes are capable of synthesizing and secreting massive quantities of non-infective surface protein (HBsAg).
A DNA polymerase that exhibits reverse transcriptase activity and genome replication occurs through an intermediate RNA template.

A protein from the X region (HBX), which is necessary for virus replication and acts as a transcriptional transactivation of the viral genes and a wide variety of host gene promoters. HBX is also thought to play a key role in the causation of hepatocellular carcinoma.

The hepatitis B virus is present worldwide with estimated 300million carriers. The UK and the USA have a low carrier rate (0.5), but it rises to 10  15 in parts of Africa, the Middle and Far East (Kumar  Clark, 2008).

HBV is a blood-borne virus, being present in all the human body fluids. It is usually transmitted by blood  blood contact (parenteral transmission). Although blood and body fluids are the primary modes of transmission, the virus may also be transmitted by contact with other body secretions such as sweat, saliva, tears, semen, breast milk, and other pathologic effusions. Vertical transmission (spread from an infected mother to a neonate) is common in some regions such as Africa and Southeast Asia. Neonatal infections such as this usually lead to a carrier state for life. The virus has been detected in some insects, particularly mosquitoes and bed bugs, but there is no evidence of the virus replication in these insect vectors. Transfusion, blood products, dialysis, needle-stick accidents among health workers, intravenous drug abuse, and homosexual activity constitute the primary risk categories for HBV infection (Kumar et al, 2008).

HBV, the cause of serum hepatitis, can also produce
Acute hepatitis,
Non-progressive chronic hepatitis,
Progressive chronic hepatitis ending in early cirrhosis,
Fulminant hepatitis with massive liver necrosis,
An asymptomatic carrier state, with or without progressive subclinical disease, and
The backdrop for hepatitis D virus (HDV) (Kumar et al, 2008).

HBV infection occurs in phases proliferative and integrative phases. In the proliferative phase, the DNA of the virus is present in episomal form along with the production of complete virions and all associated antigens. Still in this phase, there is activation of cytotoxic CD8 T lypmhocytes by the cell surface expression of viral HBsAg and HBcAg in association with the major histocompatibility complex (MHC) class I molecules. The activated cytotoxic CD8 lymphocytes then attack and destroy infected cells bearing the viral antigens. During the integrative phase, the viral DNA is inserted and incorporated into the host genome. This phase usually occurs in liver cells that have not been destroyed by the immune response by rampaging T lymphocytes. Infectivity occurs when viral replication ceases and antiviral antibodies appear in the blood.

Also, immune complexes of antigens (HBsAg) and antibodies can deposit in tissues and activate the immune system, resulting in arthritis, as well as skin and glomerular (kidney) damage.

Clinical features
Most of the clinical features of HBV infection arise as a result of the cell-mediated immune system attack on infected cells. The initial viremia causes the patient to feel unwell (malaise) along with the non-specific symptoms such as anorexia, nausea and distaste for cigarettes. Most patients recover at this stage and remain anicteric.

After one to two weeks, some patients become jaundiced and the symptoms will improve at this point. As the jaundice deepens, the urine becomes dark and the stools pale owing to intrahepatic cholestasis. Usually, the liver is moderately enlarged and the spleen can be palpated in about 10 of patients. Occasionally, tender lymphadenopathy is seen, with a transient rash in some cases. Later, the jaundice reduces and in most cases, the illness is over within three to six weeks. Rarely, the disease becomes severe with fulminant hepatitis, liver coma and death.

In patients who have immunocompromised states, such as malnutrition, AIDS, and chronic illnesses, they are more likely to be asymptomatic carriers because their immune system may not attack the invading virus.

Primary hepatocellular carcinoma is a major complication of HBV. With chronic infection, the HBV DNA becomes incorporated into the hepatocyte DNA and triggers malignant growth. There is a 200 times increase in the risk of developing primary hepatocellular carcinoma in HBC carriers as compared to non-carriers. Infections with HBV can also result in primary liver scarring and loss of hepatocytes, referred to as liver cirrhosis.

Serology Serologic tests help establish HBV infection. The extent of the infection can be determined using different markers, especially levels of antigens and antibodies in the serum. These include
HBsAg Its presence always means that there is a live virus and infection, either acute or chronic, or carrier. It appears in the blood from about 1  months (6 weeks) to 3 months after an acute infection, then disappear.

Anti-HBsAg It appears late and signifies immunity, cure or no active disease.
HBeAg It appears in the serum soon after HBsAg and it signifies active viral replication. It also signifies high infectivity.

Anti-HBeAg It appears after anti-HBcAg. Its appearance also signifies low and decreased infectivity.
HBV DNA it suggests active viral DNA replication. It can be found in the serum and in the liver.
Anti-HBcAg It is usually the first antibody to appear in. IgM anti-HBcAg signifies an acute and continuous infection while IgG anti-HBcAg does not appear until the acute disease is over and is usually not detectable for a few weeks to several months after the disappearance of HBsAg. IgG anti-HBcAg signifies an old infection.

Liver Biochemistry In the acute stage, the hepatocytes produce enzymes that are released during cell death. These are liver function enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and alkaline phosphatase. Elevated blood levels of these liver enzymes help in establishing the diagnosis of hepatitis. In the icteric stage, the serum bilirubin reflects the level of jaundice (Kumar  Clark). Serum AST reaches a maximum in 1  2 days after the appearance of jaundice, and may rise above 500IUL. Serum ALP is usually less than 300IUL.

There is no specific treatment apart from symptomatic therapy. Antiviral agents for treatment of chronic active or persistent HBV infection includes

Prevention and prophylaxis
Prevention involves avoiding risk factors such as multiple sexual partners, multiple homosexual partners (male), and sharing needles. Also, standard safety precautions should be enforced in health care centers, laboratories and hospitals in order to avoid needle-stick injuries and contact with infected body fluids.

Prophylaxis can be given in the form of passive or active immunization. Passive immunization is induced by the administration of antibodies against virus. Adults are administered with 500IU of specific hepatitis B immunoglobulin (HBIG) and newborns with 200IU of HBIG intramuscularly. Active immunization is induced with the use of a recombinant yeast vaccine produced by cloning the gene coding for HBsAg in yeasts. There is no risk of developing disease from the vaccine because it contains only the surface envelope and proteins (HBsAg). It is now given to all infants at birth, 2, 4, and 15 months. It is also given as three injections to adolescents and high-risk adults (e.g. health workers, IV drug users, etc).

The Sensory Nervous System

A Brief Description of the Peripheral Nervous System
       The nervous system consists of two main interconnected subsystems, the central nervous system (CNS) the brain and the spinal cord and the peripheral nervous system (PNS). The PNS is responsible for connecting the CNS to the rest of the body. It includes two subsystems, the autonomic nervous system (ANS) which, in turn, includes the sympathetic, the parasympathetic, and the enteric nervous systems and the sensory nervous system (SNS). The ANS is responsible for managing involuntary body functions (e.g., digestion), while the SNS is responsible for managing voluntary functions (e.g., moving a finger) and providing the CNS with information about the inside and the outside of the body (Hoyle and Arthur, 2005, p. 1-5).

        The peripheral nervous system is composed of functional units called neurons (also known as nerve cells), and they are classified into two main types 1. Sensory (afferent) neurons They receive information about the internal and external environments (i.e., stimuli) through sensory receptors, and then send this information to the central nervous system (Farabee, 2007, p. 1). 2. Motor (efferent) neurons The central nervous system issues commands and sends them to effectors (i.e., glands, muscles) through these neurons (Farabee, 2007, p. 1). The Structure of the NeuronDendrites

       A root-like structure that surrounds the cell body. Dendrites are specialized for receiving nervous impulses from another cell and transmitting them to the cell body. The dendrites branched structure ensures a strong ability to receive impulses (Weis, 1996, p. 1).Cell Body
       The part of the neuron that contains the nucleus. It receives nervous impulses from the dendrites and transmits them to the axon, which in turn, transmits them to another neurons dendrites (Weis, 1996, p. 1).Axon (Nerve Fiber)

       A tube that connects between two neurons, its main function is receiving impulses from the cell body and transmitting them to the axon terminals, and thus, to another neurons dendrites. The axon is enveloped in a protective sheath comprised of a fatty compound called myelin, and hence, this sheath is called the myelin sheath. Myelin is produced by the Schwann cells, which are the cells that surround the axon. The Schwann cells build multiple protective structures along the axon separated by small nodes, which are known as the Nodes of Ranvier. These structures are very important for neurons performance because they isolate axons from each other and help them increase the speed of impulse transmission (Farabee, 2007, p. 1 Rose, 2001, p. 1 Weis, 1996, p. 1).

               Where and How Are Sensory Stimuli Perceived in the Central Nervous System       The functional units in the peripheral nervous system are the neurons, and they are found in the form of groups of clusters known as ganglia (plural of ganglion, which is a cluster) in certain parts of the body (Ferr, 2002, p. 1 Finlay, 2010, p. 1). There are 12 cranial and 31 spinal pairs of ganglia groups, and they are responsible for managing different types of processes including perceiving sensory stimuli 1. 12 cranial pairs They control different types of processes some of them are sensory some manage voluntary functions others manage more than one type of functions including involuntary functions. The main functions of these ganglia are Receiving information from sensory receptors and transmitting it to the brain, and receiving commands from the brain and transmitting them to effectors (Farabee, 2007, p. 1 Hoyle and Arthur, 2005, p. 1 Rose, 2001, p. 1) 2. 31 spinal pairs Each pair consists of two ganglia groups, dorsal (sensory) and ventral (motor). The main functions of these ganglia are Receiving information from sensory receptors and transmitting it to the spinal cord (which is connected to the brain), and transmitting commands from the spinal cord to effectors. There are some processes that the spinal cord and spinal ganglia handle without the brains assistance, the reflex arcs, which are instant and involuntary reactions to certain stimuli. An example of a reflex arc is Removing the hand quickly after touching a very hot object.

                 How Do Nervous Impulses Move in the Sensory Nervous System       Nervous impulses move through neurons in the form of electrical impulses, which are also known as action potentials. Sensory stimuli work as stimulations for neurons to generate action potentials. Each neuron has a membrane, and by default, each of its two sides has a different electrical charge, and the difference between these charges generates an electrical voltage known as the resting potential. The axons membrane, by default, contains potassium inside (negative ions), while its outer side is rich of sodium (positive ions). The resting potential in this case is about -70 millivolts (Farabee, 2007, p. 1 Finley, 2010, p. 1 Weis, 1996, p. 1).

       When a nervous impulse is generated, the sodium and potassium ion gates get opened and become more permeable, and that enables ions to move into and out of the membrane easily. At the same time, the membrane protein channel gates get opened in order to ease the flow of ions inward and outward. Positive sodium ions move first, they rapidly rush into the membrane, and as a result, the inside becomes more positive than the outside. Negative potassium ions, in turn, move outside the membrane in order to create a negative charge on the outside equal to the positive charge in the inside. This process increases the electrical voltage in the membrane to 30 millivolts (action potential). Ions cant stay in their new positions because the protein that comprises the membrane is actively moving ions against their concentration gradients (i.e., returning them to their original positions), this process is known as the sodium-potassium pump. These interconnected processes continue and include the rest of the membrane, and as a result, the action potential moves to the axon terminals (Farabee, 2007, p. 1 Finley 2010, p. 1 Weis, 1996, p. 1).

            The point at which one neurons axon transmits an impulse to another neurons dendrites is known as the synapse. In the synapse, there is a tiny space that separates between the two neurons called the synaptic cleft. A neuron can transmit impulses through this cleft by releasing neurotransmitters, which are stored in its axon terminals in the form of synaptic vesicles. When an impulse reaches the axon terminals, it stimulates syntactic vesicles to move to the cleft where they release their contents. The neurotransmitters move to the new neurons dendrites, and then stimulate that neuron to initiate a new action potential by causing ion gates to open (Farabee, 2007, p. 1).

       After transmitting the action potential, there is a small period in which its impossible for the membrane to transmit any more impulses, this period is known as the refractory period (0.0004 of a second). The membrane spends this period returning to the default state. The neurons behavior during this period plays an important role in its performance because this behavior prevents impulses from being transmitted to the opposite direction (Farabee, 2007, p. 1 Finlay, 2010, p. 1).

Diversity in Actinopterygii

Actinopterygii or the ray-finned fishes are the most successful of all vertebrates in terms of diversity and sheer numbers. They constitute around 26,900 species out of a total of around 31,500 species of fish, thus representing more than 95 of the living fish species, and adding up to more than half of all the extant vertebrate species. They include many familiar varieties such as bass, perch, sturgeons, birchers, tuna, goldfish, cod, seahorse, eels, carp, herrings, anchovies, catfishes, goldfishes, gars, pikes, piranhas, oarfish, cichlids, mackerel, pickerel, salmon, trout sardines, and the flying fish.

Actinopterygii and Sarcopterygii are the two classes of fishes with bony endoskeletons, i.e., a cranium, vertebral column with ribs, and bones supporting their moveable fins, constituting the superclass Osteichthyes.  Actinopterygii (aktinos  ray) have the distinguishing characteristic of fins supported by thin and flexible bony rays, while the other group of fleshy-finned fishes (sarcos  flesh) bear fins supported by muscles. Ray-finned fishes have always been more diverse and thriving than their fleshy-finned counterparts and preponderate the seas, rivers and lakes in vastly greater numbers. There are in fact only a handful of living species in Sarcopterygii.

Osteichthyes first appeared in the Silurian period, 445  415 million years ago, and diverged toward the end of that period. The first Actinopterygii evolved in freshwater but gradually moved into marine habitats. Actinopterygians have a two-boned structure of the upper jaw which has proven remarkably adaptable. With the upper jaw being protrusible as a result of this structure, Actinopterygii have been able to develop a wide range of feeding habits.

The most predominant group of actinopterygii are called teleosts they have first appeared during the Late Triassic (190 mya) and evolved during the Mesozoic era (155  70 mya). The group contains the most number of living fish species and makes up 95 of Actinopterygii, nearly 24,000 species in all.

The class Actinopterygii has two subclasses, Chondrostei and Neopterygii, with the former consisting of the two orders Acipenseriformes (sturgeons and paddlefishes) and Polypteriformes (reedfishes and bichirs), and the latter consisting of the infraclass Holostei (gars and bowfins) and the infraclass Teleostei (salmon, trout, carp, goldfishes, electric eels and so on). Teleostei consists of several superorders such as Osteoglossomorpha, Elopomorpha, Cluepeomorpha, Ostariophysi, Protacanthopterygii. In all, there are 38 orders, 426 families and 4064 genera in Teleostei (Ostrander, 2000). Of teleost diversity, the encyclopedic reference Smiths Sea Fishes says the following
The tremendous diversity of size, body shape, fin development, feeding adaptations, eye structure, scale morphology, skeletal modifications, sound production, bioluminescence, production and detection of electrical currents, behavior and reproduction is unparalleled among the vertebrates. (Smith, Heemstra, 2003)  

Actinopterygii indeed sport a fantastic diversity in terms of appearance, morphology, habitat, feeding habits, defense mechanisms, behavior, lifestyle and so on. Fish usually only swim, but some of the actinopterygian species can crawl and walk (walking catfish, mudskipper), fly, or be immobile. They come in a bewildering variety of colors, shapes, skin textures and patterns within a vast range of sizes. The smallest vertebrate is a teleost called goby, a coral reef dwelling fish, that on adulthood measures 8mm. Minnows are also very tiny.  Toward the other end of the spectrum, another teleost fish called the arapaima, found in the Amazon River system, may reach a length of 2.5 meters (Wootton, 1998). Giant blue marlin can be 5 meters long with a mass of 820 kg, while sickle fish (Pachychalybinae) reach up to 9 meters. 

Actinopterygii vary widely in terms of their sensory apparatuses which extend their purview beyond vision and hearing into chemoreception, electroreception, lateral line sensation, and so on. Electric eels and some other members of Actinopterygii display an interesting defense  predatory mechanism, in that they can produce electric organ discharges which can incapacitate their prey or attackers. As a group Actinopterygii are omnivorous, feeding on all sorts of organic matter, but pose little danger to humans. Piranhas are perhaps the most notorious of Actinopterygii, for their assumed dangerous behavior toward humans. Discussing the feeding habits of Piranhas, Helfman et al (1997) say this in their book The Diversity of Fish
This subfamily , the Serrasalminae, contain about 60 species, some of which are predatory, other that are scale-eating opportunists and specialists, and some that are largely herbivorous, such as the pacus and silver dollars. Despite their reputation and potential for doing damage, many purported attacks on human by piranhas actually result from postmortem scavenging on drowning victims.

Our water planet is rich in habitats and ecosystems, and Actinopterygii thrive in almost all of the aquatic environments, including extreme types such as subterranean caves, polar seas, desert springs, turbulent rivers, ephemeral pools, and mountain creeks. The diversity of the habitats is helped by the fact that some of the ray-finned fishes can spend considerable time out of water. The Siamese fighting fish can breathe oxygen directly from the air, besides possessing the capability of extracting oxygen from the water like normal fish.

The depth of actinopterygian water habitats can range from 0 to 7,000 meters, and temperatures from -1.8C to 40C. In terms of salinity and pH, 0  90 ppm and 4  10 are the numbers respectively. These fishes can live in environments that have almost no oxygen to fully oxygen-saturated ones. Some species of Actinopterygii migrate between fresh and salt water (called diadromous) for example, salmon migrate from saltwater to freshwater in order to spawn while freshwater eels do the reverse. As for geographical concentrations, freshwater ray-finned species teem in places like Amazon River Basin and wetlands of Southeast Asia, while marine species have particularly proliferated around coral reef systems such as the Great Barrier Reef of Australia.

Most of these fish lay eggs but some species which include the familiar guppies and swordtails withhold the eggs inside their bodies until they are ready for hatching. In seahorse and a few other rare species it is the male that receives the eggs. Such species are called ovoviviparous the males keep the eggs inside a special pouch inside the body.   Usually these fish do not provide any care for their offspring, but certain species protect them in various peculiar ways. For example, the females of some African cichlids keep their eggs in their mouth and even after they hatch the young are retained in the mouth for a period.

The diversity with the actinopterygians can be better appreciated by taking a look at some of the unique features of some of the major families of this class

Despite comprising a meager 23 species, sturgeon are relatively quite abundant both in marine and freshwater environments. The females produce an enormous number of eggs, which is a factor that has contributed to their success. They are among the largest fish occurring in freshwater environments. The Russian beluga sturgeon can reach up to 8.5 meters, weighing 1,300 kg, and the North American white sturgeon can reach a length of 4 meters, weighing 590 kg.

While sturgeon feed on whatever they can suck up off the bottom, Gars catch their prey by employing ambush tactics. Gars have a heavy protective armor, and in order to keep their weight buoyant they have a large air bladder which also functions as a lung. Gars reach one to two meters in length, only the alligator gar reaches up to 3 meters. 

Herrings are exquisitely adapted to avoid the predators. They have large silvery scales that reflect light to dazzle predators during the daytime. Furthermore, these scales are deciduous, so even when even caught a herring can escape shorn of its scales and grow them again. They have a streamlined shape which reflects minimal light, making them less visible to predators attacking from below.

There are over six hundred species of eels this family shows a surprising variety of forms. Both European and American eels migrate thousands of kilometers in ocean to Sargasso Sea (Atlantic Ocean), where they spawn in deep water. From leaf-like larva they transform into elvers at which stage they migrate long distances upstream to some freshwater source and mature into adulthood (Moyle, Cech, 2004). The African electric fishes, belonging to the same family as eels and herrings has over one hundred species and live in murky swamps of tropical Africa. They find prey and communicate with one another using electrical signals. An enigmatic aspect of these fish is that in some species the brain-to-body ratio is very close to that of humans. These fish are also found in other continents, including North America, but in much lesser numbers.

Salmon, trout, whitefish, and grayling and about one hundred and fifty other species make up the family Salmonidae. They are a highly migratory species, superbly adapted to cold water. They are the dominant fishes in the streams and lakes of north temperate regions. Besides being highly valuable as commercial fish, they are very popular with anglers as well as fish biologists.

By contrast, bristlemouths are fishes known to few people, and yet they are perhaps the most numerous fishes in the world. Tiny in size, reaching only 5 cm or less in length, they teem in deep seas. At times sonar beams from submarines are reflected back from them creating a false notion of the bottom.

The teleost superorder Ostraiophysi comprises fishes that dominate most of the world, including minnows, suckers, loaches, South American electric fishes, catfishes, popular aquarium fishes such as tetras, and the notorious piranhas. One quarter of all known fishes belong to this group. Of the many reasons for their success particularly noteworthy are their acute sense of hearing, their pharyngeal teeth, and their fear scent. They have auditory apparatus remarkably like that of mammals the pharyngeal teeth make the mouths of these fish specialized for many types of foods just like mammalian teeth the fear scent is given off by an injured fish so that its school members can dive for cover. The family Cyprinidae of this superorder, consisting of minnows, carps, goldfish and over sixteen hundred species is the largest single family of fishes. A prominent reason for their success is the presence of stout spines on the dorsal and anal fins which makes them harder for predators to capture. Another family suckers, with about sixty species, is a very successful group in North America. They are specialized for sucking and scraping algae, small invertebrates and organic debris from the bottom. Catfish is another successful family, with forty species. There are catfish that can reach over 5 meters and in length as well as those that are so tiny they can slip into the gill cavities of larger fish. One of the reasons for their success is their secretive, night-oriented behavior. While carps, minnows and the Cyprinidae rule the day, catfishes rule the night.

Flying fish are among the most curious members of the actinopterygian group, for obvious reasons. They leap out of water and glide as much as 100 meters with the help of their wing-like pectoral fins. The flying fish use their wings only for gliding and not to power their flight.

By contrast, there is a freshwater family of hatchet fishes which have hatchet-shaped breasts that contain large muscles needed to move their pectoral fins rapidly up and down, thus achieving true flight.

The famous evolutionary biologist, Richard Dawkins, pays this tribute to the teleost variety in his book, The Ancestors Tale A Pilgrimage to the Dawn of Evolution (2004)

The teleost fish are the great success story among modern vertebrates  there are some 23, 500 species of them. They are prominent at many levels of underwater food chains, in both salt and freshwater. They have managed to invade hot springs at one extreme, and the icy waters of the Arctic seas and high mountain lakes at the other. They thrive in acid streams, stinking marshes, and saline lakes... The teleost pilgrims arrive in a jostling crowd, brilliant in their variety.

Adaptive Immunity and Antibiotic Resistance

    The immune system of the human body consists of different cells and molecules which play different roles in response to infection. These responses are divided as innate and adaptive immune response. Innate response acts on different infectious agents the same way no matter how often they are encountered. The adaptive immune response has immune recognition to specific invading microorganisms that the body is previously exposed to and that repeated exposure to those particular microorganisms elicits a stronger immune response. There are bacteria, however, that are able to evade not only from the bodys immune system but also from the actions of antibiotics designed to eliminate them. These bacteria are able to develop mechanisms which allow them to become resistant to antibiotics from which they are previously susceptible to. They also have mechanisms by which they are able to confer this antibiotic resistance to their progeny.

The adaptive or acquired immune response has four important features specificity, diversity, memory, and self vs. non-self recognition. Specificity refers to the ability of the immune response to act on specific antigens that it has previously encountered. This ability is due to the presence of receptors on B cells and T cells which recognizes specific antigens present on an invading pathogen. Diversity refers to the ability of the B cells and T cells to randomly generate very large and diverse repertoire of antigen receptors which increase the chances of these cells to recognize offending microorganisms, thereby triggering the immune response. Immunologic memory is a feature of the adaptive immune response wherein previously encountered antigens are recognized by memory cells in order to mount a stronger immune response. The ability of the body to prevent self-antigens from triggering an immune response is because of immunoregulatory mechanisms which discriminate self from nonself antigens mediated by suppressor T cells. These features of the acquire immune response enable vaccinations to generate a protective immunity against a particular disease. Vaccines contain known antigens from a particular pathogen which stimulate specific receptors from the diverse repertoire of antigen-specific on the surface of B cells and T cells. Killer cells and antibodies are elaborated which mount a strong immune response once memory cells are challenge by the same antigens. The artificial immunity is achieved without getting the actual disease since vaccines use killed or live but attenuated pathogens which render these pathogens harmless. Other vaccines contain only the antigens to elicit the immune response without the actual pathogens.

Mycobacterium tuberculosis is the infectious agent which causes tuberculosis. Its route of entry is primarily through the lungs. Once the tubercle bacilli enter the body, the initial response of the system is through the cell known as alveolar macrophage which engulfs the bacilli and inhibits its proliferation. In the event that this process does not effectively kill all bacilli, a type of lymphocyte known as CD4 T cells express specific antigen receptors which recognizes the bacilli and recruits and activates other immune cells such as monocytes and dendritic cells to the site of infection to further amplify the immune response. Immune cells also stimulate the release cytokines and antibodies which provides additional defense and immune against M.tuberculosis Schluger (1998).

When infectious agents elude the immune defense, infection ensues which leads to disease. Although antimicrobial agents are available to eliminate the invading microorganism, there are bacteria capable of eluding them as well. This happens when the bacteria acquires the ability to resist the action of the antibiotics due to gene mutations after repeated exposure to the antibiotics. There are four mechanisms of antibiotic resistance. One mechanism is through drug inactivation or modification which renders the drug ineffective. This is due to enzymes that are elaborated by bacteria which deactivates the drug. Another mechanism is the alteration of the target site where the antibiotic binds with the bacteria. This prevents the drug from binding to the bacteria and allows the bacteria to escape the toxic effects of the drug. Some antibiotics disrupt metabolic pathways critical to the survival of the bacteria. However, there are some bacteria that are able to resist this effect by altering their metabolic pathways an turn to using substrates not inhibited by the antibiotic. Some bacteria also acquire the ability to reduce the permeability of the drug into the bacteria or increase the expulsion of the drug out of the bacteria which effectively reduces the effect of the drug.

Bacteria acquire antibiotic resistance through the transfers of resistant genes from other bacteria with resistant mutations. The transfer of genetic material between bacteria is referred to as horizontal gene transfer. The genetic exchange is possible through several mechanisms. Bacteria can acquire antibiotic resistance through uptake and expression of resistant genes from other bacteria. This process is called transformation. Transduction is another process which transfers resistant genes from one bacterium to another through a bacterial virus known as bacteriophage. Bacteria can also transfer resistant genes through direct cell-to-cell contact mediated by genetic material known as conjugal plasmids or conjugal transposons.

Affects of Fish Excrements to Global Warming

Recent studies have revealed that fish play an important and pivotal role in balancing, not only the marine ecosystem, but also the global ecosystem as well. This paper discusses the role of fish excrements to global warming.

    Prior to the recent studies it has been thought that the major source of calcium carbonate in the seawater are the planktons. Recent studies change this fact and now it is revealed that the fish excrements are responsible for providing around 15 of Calcium Carbonate in the ocean water. Fish excrements contain guts, which are mainly composed of calcium carbonate. (Role of Fish in the Carbon Cycle, 2009)

Calcium Carbonate is the key compound, which balances the acidity and pH level of ocean water. If this compound is not generated in sufficient quantities it will not only endanger certain marine species like coral reef and many shell bearing aquatic animals due to increased acidity, but will also become a primary reason of rise in temperature of the ocean water. This is because calcium carbonate produced by fish will absorb CO2 and will keep the pH of the ocean water in balance. This will also control the rise in sea temperature due to increased acidity of water. Researchers are hopeful that if the amount of CO2 in the ocean water increases so will the fish produce the amount of calcium carbonate, as they will naturally try to keep the balance.

Though this prospect seems promising to everyone concerned about global warming or rise in sea levels, but in reality the situation is very grave. This is because the increasing amount of CO2 emissions will be absorbed in the near future, but overfishing will result in a highly diminished population of fish in the sea and thus they wont be able to keep the ecosystem of the ocean water on balance as hoped by many. Even now many fisheries and natural habitats of fish are in grave danger and many colonies and communities of fish are considered endangered species. Even large aquatic mammals are endangered because of commercialized fishing and whaling. (OShea  Odell, 2008)
Fish also act as sentinels to coral reef. Coral reef is also a large producer of calcium carbonate. But they are also highly vulnerable to CO2, which if in high concentration may destroy large colonies of coral reef. Though coral reef is also a producer of calcium carbonate it is never in very large quantities to counterbalance the increasing amount of the acidic gas in the aquatic ecosystem. This gas proves to be highly fatal for the reef. Fish excretion plays an important part in shielding the coral reef from the lethal affects of CO2. Thus, if the quantity of fish is diminished then it will also result in the downfall of the coral reef. Therefore it is extremely important to control the commercial overfishing in the coastal or open waters. (Suzuki  Kawahata, 2002)

The recent studies have proved that how important fish are playing their part in reducing global warming. If overfishing is not controlled it will result in the loss of the key sentinels of the aquatic ecosystem and the result will be warmer seas, higher sea levels and extreme weather conditions across the globe. Therefore it is a matter of extreme importance that the concerned authorities take it seriously before the time runs out.

The effects of temperature on metabolic rate as seen in the Tropical Zebra Fish (Danio rario)

Zebra fish (Danio rerio) subjected in 30oC water samples had larger mass specific oxygen consumption rate.  They had 3.5X more mass specific oxygen consumption rate than zebra fishs treated in 20oC water.  

    Oxygen demand by all animals is seen to be driven primarily by their metabolic needs.  Fish are poikilothermic animals and in being so are thermal conformers which makes there metabolic rate dependent on the temperature of the environment they are in (Glencross, 2006). The lab experiment performed uses the Winkler method to study the effects on Zebra fish (Danio rario).  This study was done in two temperatures of water.  One set of fish were acclimated to 20 degree Centigrade water and the other to 30 degree Centigrade  water.  Metabolic rates were measured during this process and it was noted that Zebra fish exposed to cold water (20 degree) had lower metabolic rates than those that were exposed to warm water (30 degree).  In fact, their oxygen consumption rate was 3.5 times as high as the alternate fish.  This study was designed to test the hypothesis that water temperature affected metabolic rate in a poikilothermic animal.  This paper will discuss the results of this study in relation to other studies done.

    It is known that Zebra fish like many invertebrates are thermal conformers .  In these animals the outside temperature affects metabolism and therefore their need for oxygen consumption.  It also means that there is only so much this animal can take related to temperature. On the other hand, we as humans have an internal body temperature that is not affected by outside temperature.  In other words humans and mammals can live almost anywhere based on the fact that they can regulate their own temperature but thermal conformers are restricted by the temperature of their habitat (Glencross, 2006). However, the study done by Cortmelia, Beitinger,  Kennedy tell us that Zebra fish can live in a different environment, it is just somewhat limited.  In a study done by Cortemeglia, Beitinger,  Kennedy, 2006) in which Zebra fish were placed in the wild under different temperatures.

    Cortemeglia took zebra danios from two pet stores  in Northern Texas.  They were placed in fibreglass microcosms outside.  The fish were allowed one hour to adjust to water temperatures before the testing began.  In this case the temperatures were at four levels instead of the two used in our experiment. 13 fish out of 68 survived at temperatures of 7.5 degrees Centigrade and none survived at a 4 day exposure of a cold snap that dropped the temperature to 4 degrees Centigrade.  It is noted that the lowest surviving temperature was 5 degrees centigrade. Testing throughout the Winter, however, noted the same type of results that were found in this lab study including that the metabolic rate was much lower as was oxygen consumption at lower temperatures, however, survivability can only be reduced to 5 degrees and not lower.(Cortemeglia, 2006).

    Cortemeglia (2006), showed throughout their study that metabolic rates and oxygen consumption increased as the temperature increased and was much lower in the fish that were in the coldest microcosms. This is further supported by a study done by Kranenberg, Boogart, Jos in which they tested the oxygen profile of Zebra fish in an experiment which concluded that tropical fish consume at least 6 times more than non-tropical fish. It was noted throughout their study that oxygen rates were lower in those fish that lived in colder water and therefore they did not need to support a metabolic rate so high.  This reduces the amount of food they must eat to maintain. This is part of the reason why the fish died in the Texas study.

    In conclusion, the lab study conducted is well supported by previous research.  The results obtained here run very close to the results noted in the other studies though some of the technique used here may not have been as good.  An example, in the Texas study, the fish were acclimatized first and they were never touched by humans which is not true in our case. The temperatures might have been colder as some of the studies being done now show that Zebra fish in particular are able to withstand lower temperatures and this might affect our results.

Down syndrome

    Down syndrome is a genetic disorder that is highly determined by the age at which the mother conceives a child. Increase in age increases risk of having a baby with Down syndrome (Crane  Morris, 2006). As such, it is of importance to have accurate screening tests in order to understand likely risks during pregnancy. In addition, it is important to know reasons why these trends exist in able to counter Down syndrome effectively (Hall et al, 2007). The understanding of how advances in screening Down syndrome have grown and the steps taken by mothers who screen positive has piqued interest in this topic. As such, the paper looks into the article screening and antenatal diagnosis of Downs syndrome by Stephanie Brunner published in Medical News Today on 27, October 2009. This is compared with the journal article Wrongful deaths and rightful lives-screening for Down syndrome by Frank Buckley and Sue Buckley, a 2008 publication in Down Syndrome Research and Practice journal, volume 12, issue number 2. 

Summary of Medical News Today article
    The article presents a report from the British Medical Journal showing an increase in mothers diagnosed of Down syndrome as from 1989 to 2008. The percentage of women aged 37 years and below who choose screening increased by 40 percent. The proportion of older women opting for screening however remained almost constant over the same time period. Increase in diagnosis was attributed to the rising number of elderly mothers.

    The article also notes that even though diagnosis and screening has increased, there was a drop in the number of children born with Down syndrome. This was due to the fact that most women choose to terminate the pregnancy whereas others underwent antenatal screening. The article raises the question of why older women chosen did not opt for testing yet they are at greater risk of bearing children with Down syndrome. The article therefore notes that reluctance to testing in older women means a continued risk of Down syndrome children in the population (Bruner, 2009). 

Journal findings
    Buckley  Buckley (2008) use the same data as that used to present the findings in Brunners article i.e. data from National Down Syndrome Cytogenetic Register (NDSCR). The article acknowledges that there has been an increase in Down syndrome births despite an increase in antenatal screening awareness and an increase in live births. England and Wales has had screening policies over the time span which has led to a decrease in live births by 44 percent. Increase in number of older mothers has been noted just like in Brunners article. The most interesting finding is that Down syndrome screening in England and Wales cause a reduction of live births every year and a significant majority (400 out of 660) of babies lost usually do not have Down syndrome. The research therefore concludes that screening tests applied are highly responsible thus proposing for screening during the first trimester. The two articles therefore show that screening has led to reduced Down syndrome births due to increased screening and termination of pregnancies but Buckleys and Buckleys article warns that termination of pregnancies lead to loss of Down syndrome free children thus calling for a revision of the screening tests.

    The article by Buckleys and Buckleys is based on scientific methods as it includes actual research, has a literature review, analyses secondary data from NDSCR to come up with its findings. The article is sufficiently detailed. This is unlike Brunners article that is simply reporting findings by a research body. Brunners article is however easy to understand and interesting as it directly presents synthesized information. The two articles are however important since they help in bringing the same message clearer. While Buckleys and Bucklys article provides a scientific reasoning behind increase in down syndrome diagnosis and decrease in live births, the other article presents the same information in a simpler and more direct manner.

    The understanding of the trends in screening and diagnosis is of Down syndrome is important in making decisions regarding reducing Down syndrome births. It is however important to make sure that termination of pregnancies gives the least room for false positives.