Biology

Breast cancer is a disease that occurs due to malignant cells forming in the breast tissues and mostly occurs in women though men too can develop it (Slowik). It is the 2nd most cause of death among women second only to lung cancer. Estimates from the American Cancer Society indicate that 192,370 women were expected to be diagnosed in 2009 and 40,170 women were expected to die from breast cancer. In men, the cancer is very rare and roughly has a less than 1 occurrence rate (Warren and Devine). Breast cancer occurs due to abnormal cell growth that goes out of control and forms masses of cells or tumors. When these masses of cells have their origin in the tissues of the breast, it becomes a breast tumor hence breast cancer. There are broadly two types of breast cancers Lobular carcinoma and ductal carcinoma (Slowik). If the cancer cells in the breast are restricted to the breast lobule and ducts, then the cancer is called non-invasive. If however cells have moved from the ducts and lobules to the tissues surrounding the breasts then it is an invasive cancer.

There is no definite cause of breast cancer that is known. However, risk factors that cause cancer are known. Some of the risk factors cannot be avoided or changed.

Gender is one such risk factor. Women are at a main risk of the disease due to their gender. Though men can get the disease, chances are 1 in 100 times.

Age also increases the chances. As women get older, their chances of getting breast cancer are higher. It is not however unlikely for younger women to get breast cancer.

Genetics also matters. Inherited genes may be cancerous and lead to the cancer.

Family history and cases of breast cancer in ones family also increase the chances. However, 70-80 of a lot of women with breast cancer usually do not have a history of the disease in their family.
Radiation exposure on the breast that might have occurred due to radiation treatment on areas close to the breast such as the chest increases the risk. The risk is high if exposure was at an early stage such as teenage years.

Menstrual cycles and periods that occur in women at early ages (before 12) increase the risk of the disease due to exposure to estrogen and progesterone hormones.

Different races have different risks of breast cancer. White women are at a higher risk of breast cancer compared to African-American women.

Density of the breast tissue in women. Women with dense breast tissue, an indication that there is more of the gland than fatty tissue, have a higher risk.

A history of breast cancer in women also increases the risk as women with previous case of breast cancer have a higher chance of contracting breast cancer in the non-cancerous breast (Stephan).

A lot of breast cancers do not have symptoms that are obvious and they tend to vary. There is no pain and therefore harder to detect. However, some signs could indicate breast cancer. Presence of a lump in the breast or armpit is a classic indicator of breast cancer. The swelling may be due to changes in the hormones but if persistent, it should raise concern. Change in the size of the breast and shape is also an indicator. A change in breast size of a mature breast might mean a swelling of the milk ducts. A mammogram is advised to note the changes. Fluid leak from a nipple may also occur and the leak, of a non-bloody nature, occurs due to changes in hormones. However, if that leak is from one nipple and is bloody, tests should be conducted to discover the cause. Changes in the size, shape, color, texture of the nipple or the areola could indicate signs of breast cancer but when discovered at its early stages, it is curable. Women are advised to do breast self-examinations as part of a monthly routine. Annual mammograms and checkups by physicians are recommended. Catching the cancer early is vital (Stoppler).

The treatment of the cancer is determined highly by the type of breast cancer, the stage and sensitivity of the hormones. Treatment may consist of Surgical operations which involve the removal of the tumor (lumpectomy), entire breast (mastectomy) and one or several of the lymph nodes Radiation therapy involves use of energy beams with a lot of power to eliminate the cancer cells e.g. x-rays. The beam is focused on the body externally or internally (brachytherapy). There are however side effects such as fatigue and rashes Chemotherapy involves the use of drugs to kill the cancer cells. Loss of hair, nausea, fever and vomiting are some of the side effects Hormone therapy focuses treatment on the cancers caused by sensitive hormones. Use after surgery and other treatments to decrease occurrence of a return is not rare (Cancer Research UK).

Occurrences of breast cancer are more common in women. Focus on research and studies on how it can be prevented in women will help both men and women. Developing countries have also started showing increases in cases of breast cancer due to change in lifestyles. There has been awareness on breast cancer worldwide.

Lung cancer is a disease in form of abnormal growth of cells in the tissues of the lungs. This usually results in an uncontrolled growth of cells and leads to a lump that begins to grow within the lung which can later spread to other parts of the body. Metastasis is the term used to refer to the spreading of the tumor (Stoppler). According to statistics from the CDC (Center for Disease Control and Prevention), lung cancer is the highest cause of all cancer deaths in men and women (CDC). The estimated number of new lung cancer cases in the United States in the year 2009 was 219,440 while the number of deaths totaled 159,390 (National Cancer Institute). Lung cancers are broadly categorized into two Non-small cell lung cancer and small cell lung cancer (Lee).

The main cause of lung cancer is tobacco smoking which takes up about 90 of all lung cancer cases. It mostly occurs in adults above the age of 45. Cigarette and cannabis smoking have similar smoke effects on the lungs. Secondhand smoke can also cause lung cancer among non-smokers. The number of non-smokers who die of lung cancer is significant, about 3,000 adults each year. There are other factors that may lead to increased risk of getting lung cancer history of lung cancer in ones family, radio therapy on the lungs, exposure to chemicals known to cause cancer e.g. uranium, beryllium, chloromethyl ethers and diesel exhaust, air pollution and drinking of water with high amounts of arsenic. Radon gas and asbestos also increase risk of lung cancer (Cancer Research UK).

A big problem with lung cancer is that its not easily detectable. Symptoms usually vary with the type of lung cancer and may take some time to develop. Most diagnosis occurs after the disease is at an advanced stage. An X-ray on the patient is required to see the cancer and a biopsy done to confirm diagnosis. Symptoms include shortness of breath, fatigue, loss in weight, consistent coughing (sometimes with blood-stained sputum), chest pains and loss of appetite. With confirmed lung cancer other symptoms continue to occur such as pain in the joints, facial swelling, paralysis of the face, general weakness, drooping of the eyelids and bones become tender. The symptoms could be due to other conditions so it is vital to see a physician who performs some tests to confirm diagnosis. Blood work, MRI, CT scans, X-rays of the chest and positron emission tomographies are some of the tests done (Stoppler).

Generally, the earlier the detection of the lung cancer, the better chances there are of survival. An estimated 60 of lung cancer patients die in a year. Treatment of the disease is highly dependent on the type and stage of the lung cancer. It can normally be divided into 4 stages with each stage varying with the extent of the spread of the cancer. There are 3 options for treatment each with side effects and dependant on the type and stage of cancer Surgery, radiation therapy and chemotherapy (Radiological Society of North America).

Surgery is the main treatment used for patients in the early stages. It aims to totally remove all the tumor cells. If the tumor recurs, it is removed again (RSNA). Its side effects include the accumulation of air and fluid in the chest, chest soreness and short breathes.

Radiation therapy is the other form of treatment. It can be used as the main treatment before surgical operations to reduce the size of the tumor and after surgery to remove any tumor cells remaining. It involves delivering X-rays with high energy to the tumor cells to destroy them. The treatment is given in stages and sessions.

Chemotherapy is a treatment that involves prescribing drugs that are toxic to the tumor cells. Drugs are administered intravenously mostly after surgery to remove any small tumor cells that may have remained. Its used during any of the lung cancer stages (RSNA). It has been found that combination of this treatment and radiotherapy is efficient though various side effects may occur. Side effects include loss of hair, sores on the mouth, nausea and fatigue.

Overall however it is best to avoid the disease as cancers are rarely fully cured. It is better to avoid the disease by quitting smoking which is the highest cause. Avoiding secondhand smoke and dangerous chemicals in the workplace could also go a long way in preventing lung cancer (Fayed). Early detection is also vital for a higher chance of treatment survival.

Depression is a mental disorder characterized by a feeling of intense sadness for excessively long periods of time that tends to affect with the normal functioning (Fawcett).  However, depression not only affects the mind but also the body (Mayo Clinic Staff).  The manner in which an individual feels, thinks and behaves is altered in depression and daily functioning is seriously affected (Mayo Clinic Staff).  Depression is considered to be a chronic disease that requires persistent treatment in the form of psychotherapy and medication.  There are several forms of depression including major depressive disorder, dysthymic disorder, postpartum depression, Pre-menstrual dysphoric disorder, Seasonal affective disorder, psychotic depression and seasonal affective disorder (NIMH).  Major depression is a condition in which the individual develops a range of symptoms that affect with normal functioning and can be disabling in nature.  There are high chances that an individual would experience an episode of major depression once in their lifetime.  However, there are also chances that the individual may have more than one episode of depression in their life (NIMH).  The symptoms tend to persist for at least 6 months and are characterized by the development of 5 or more symptoms.  If fewer than 5 symptoms occur for at least 2 weeks, then such as episode of depression is termed as minor depression (Ballas).

Depression is the most common mental disorder after anxiety.  Depression can occur in any age group but is more common in teens, young adults, and middle-aged individuals.  Depression can also occur in children and elders.  During the later part of the 20th century, there were more number of substance abuse cases and hence, more and more people with depression have been committing suicide.  Depressive episodes can go on for period between 6 months to 2 years without any treatment.  About 17 of elders have depression, and it may be more common in individuals who have had depression earlier in life (Fawcett).  Depression tends to occur more often in women, especially teens and young adults.  The exact cause for this has not been understood clearly.  Scientists think that a woman is more likely to seek help for depression than men, which means more number of documented cases of depression (Ballas).    Depression can occur along with a number of other disorders including anxiety disorders (such as PTSD, obsessive-compulsive disorder, panic disorder, Generalized anxiety disorder), substance abuse, social phobia, medical illnesses (such as stroke, cancer, HIV, diabetes, heart disease, Parkinsonism, etc).  If depression is treated, there are better chances of the co-existing disorder to improve.  Bipolar disorder is a mental disorder characterized by the development of bouts of mania along with bouts of depression (NIMH).    

Causes
The exact cause for depression has not been understood clearly although experts feel that it is a combination or interplay of genetic, biochemical, environmental and psychosocial factors.  Depression is often found to occur in families.  One reason for this is that it is often inherited, but here may be some kind of learned behavior transmitted down the family (Ballas). Multiple genes are involved in the transmission of depression down families (NIMH).  There may be certain changes observed in the brain scans (observed through neuro-imaging such as CT and MRI scans) of individuals suffering from depression.  Besides, it has also been found the levels of various neurotransmitters (epinephrine, dopamine, and serotonin) present in the brain are abnormal in depression (NIMH).  Certain events in life such as death of a near and dear one, problems with a partner, witnessing or experiencing a stressful situation, chronic stress, disappointments at school, workplace, or at home, brain disorders (dementia, brain tumors, multiple sclerosis), certain medical illnesses, isolation, drugs such as antihypertensive agents and sedatives, childhood trauma, major illnesses, etc, can lead to depression (Ballas).      

Symptoms
Usually the symptoms of depression develop gradually over a few days or weeks.  Some people with depression have problems with experience of emotions and events that were previously enjoyable would become lack luster.  The individual is withdrawn socially and would progressive experience a hopeless life and become more and more helpless.  Functioning at the home, school, workplace or in social settings is seriously compromised (NIMH).  The individual feels lonely, withdrawn, guilty, worthless, restless, irritable, and tired.  Energy levels are low and suicidal ideation is common.  Appetite changes along with weight gain or weight loss are also common.  The individual experiences difficulty with concentration.  Activities that were once enjoyable (such as sex, holidays, social functions, etc) are now painfully stressful (Ballas).  The individual also has problems with thinking, sleeping and body movements (Mayo Clinic Staff).
 
Diagnosis
The diagnosis of depression is made based on the history, family history, drug history, symptoms, signs, blood tests, urine tests, mental evaluation, depression questionnaire, and is established based on certain guidelines mentioned by Diagnostic and Statistical Manual of Mental Disorders  Fourth Edition, Text Revision (DSM-IV-TR).  The history should try to determine previous events of depression, drugs being used or family history of depression.  Laboratory tests such as urine tests, blood tests are done to determining the functioning of various organs of the body and to rule out substance abuse.  A mental evaluation of the patient is conducted to determine the thoughts, feelings, and behavior of the individual (Fawcett).  DSM-IV-TR is guidelines used to diagnose depression based on the experience of 5 or more symptoms for more than 2 weeks.  Depressive symptoms should be existent along with difficulty in functioning (Mayo Clinic Staff).    

Treatment
Depression is treated using medications, psychotherapy and other modalities.  Several antidepressants are useful in treating depression indulging Selective serotonin reuptake inhibitors (SSRIs), Serotonin and nor epinephrine reuptake inhibitors (SNRIs), Nor-epinephrine and dopamine reuptake inhibitors (NDRIs), Tricyclic antidepressants, Monoamine oxidase inhibitors (MAOIs) and atypical antidepressants.  SSRIs are safe, effective and cause lesser side-effects.  SNRIs have similar side-effects as SNRIs but can cause dizziness and sweating (NIMH).  NDRIs does not cause sexual side-effects but can increase the risk of seizures.  Trazodone and mirtazapine are the most often used atypical antidepressants.  TCAs and MAOIs are known to be effective but have a number of side-effects and hence are reserved once the SSRIs or SNRIs do not work or cannot be administered.  If the patient has a co-existing anxiety disorder or other mental disorders, anti-anxiety drugs may be administered (Mayo Clinic Staff).

Psychotherapy is an important part of the treatment for depression.  In these sessions, the patient can understand the unhealthy thoughts and behaviors and develop better means of coping with problems of life.  It can be administered individually or during Group therapy (Fawcett).

Other forms of therapy recommended for Electro-convulsive therapy, residential therapy and hospitalizations.  Depression is usually treated on an outpatient basis and only in the case of serious depression along with sucidical tendencies, would hospitalizations be required  (NIMH).  

Complications
Usually, if the symptoms of depression are treated promptly, using antidepressants, psychotherapy, and other modes, the outcome is good.  However, the toll may be serious especially in those who do not receive any kind of treatment.  Such individuals would have problems for the rest of the lives.  Some of the common complications that may arise from depression include substance abuse, alcohol abuse, problems with relationships, family issues, heart disorders, suicidal ideation, isolation, etc (Mayo Clinic Staff).

Introduction
Acid rain is defined as a form of precipitation that has abnormal levels of nitric and sulfuric acids (Briney, 2010). The rain is caused by the reaction of sulfur dioxide and nitrogen oxide with the atmospheric air, resulting into the formation of nitric acid and sulfuric acid among other compounds (Briney, 2010). According to available information on acid rain, it can either be inform of wet or dry deposition depending on the weather conditions. Acid rains can be caused by natural andor man-made activities.

The major natural causes include volcanic activities and the decaying process of vegetation which have been identified to produce both nitric oxide and sulfur dioxide (Thinkquest, 2000). However, statistics claim that the contribution of these natural factors is quite negligible. Man-made activities cited for causing acid rains are the huge release of exhaust gases, especially sulfur dioxide and nitric acid, from production companies (USEPA, 2007). The major contributors here are industries using fossil fuel in the production process.

Effects of acidic rain
Acid rains have negative effects to almost all aspects of human life as they affect the environment and its habitants as well as poses health threats to mankind. Acid rain increases acidity of surface water thus threatening the lives of aquatic animals (Beildler, 2008). A pH of below 5 in surface water is required for ensuring the existence of fish and other aquatic animals (Thinkquest, 2000). The reason behind the death of fish and other aquatic animals is due to the low pH and high aluminum concentrations found in water as a result of acid rain (Briney, 2010). According to available information, acid rains have in the past led to the extinction of insects and fish species in some rivers, streams and lake waters.

The second effect of acid is the negative impact it has on the soil. The human community relies on soil for agricultural production for its food security. Soil on the other side is influenced by microbes as well as other chemicals such as calcium and magnesium for its sustainable fertility (USEPA, 2007). Acid rains lead to denaturing of some species of microbes due to the high acidity thus compromising their effective functioning (USEPA, 2007). Still, acid rains, with its hydronium ions react with aluminum, calcium and magnesium from the soils thus compromising the life of sensitive plant species (USEPA, 2007). All these means that the soil will be deprived both of its microbes for ensuring fertility and existing useful chemicals for sustaining plant life.

Another serious consequence of acid rain is seen on forests and other vegetations. According to scientific evidence in records, forests in high altitudes are particularly affected by acid rains. The main reason here is the fact that this forests are usually surrounded by clouds, fog and snow, forms, which acid rain can take (USEPA, 2007). The threat here is mainly posed by the nutritional implication acid rains have on the soil as well as leaf surface damages thus compromising the sustainable survival of the plants. The effects vary depending on the type of type as well as the level of acidity in the rains. For example, the leaching of calcium from red spruce compromises the plants ability to tolerate cold thus risking sustaining winter injury or death (Thinkquest, 2000). However, the effects of acid rains on food crops is found to be minimal due to agricultural practices like fertilizer and lime applications for the restoration of lost nutrients and soil pH respectively.

Although acid rains are not directly linked with health complications in the human body, acid air pollution do have serious health complications (Beildler, 2008). First, the problem of lung and breathing in asthmatic members of the community is has been closely attributed to acid air pollutions (Beildler, 2008). Still, to be noted is the fact that most of our nutrition comes from the soils. This has the logical implication that whatever we take as food or drink has been affected by acid pollutions. This is the reason behind most kind of sicknesses such as cancer and premature deaths.

Lastly, acid rain affects non-living things such as buildings, bridges and metallic structures (Briney, 2010). Areas like India and Italy among other countries are examples nations those structures have been affected by acid areas. Such rains lead to corrosion, discoloration and even fracturing of buildings (Briney, 2008). This makes acid rains a major threat to the long term existence of national monuments. On metallic structure damages by acid rains can be evident from the corrosion effect the acid rain brought to railways in some parts of Poland.

Conclusion
It has been established that acid rains are a major threat to the soil, surface water, and its habitants, forests and man-made structures such as building and infrastructure. They are thus a major threat to our sustainable social economic development. Despite this threat, mankind activities are the main cause of acid rains. Energy production using fossil fuels, production industries and cars are all to be blamed for causing acid rains (Briney, 2010). Such concerns for the safety of the world has resulted into safer production processes that limit the amount of acid gas released to the air by industries. Nevertheless, there is much need to device more effective ways of mitigating occurrence of acid rains in the global community.

Structure
Hemoglobin is a protein that is found in the red blood cells. The hemoglobin molecule has a tetramer structure made up of four polypeptide chains two beta globins and two alpha globins. The alpha globin chain has 141 amino acids while the beta globin chain is made up of 146 amino acids (Nabili, n.d). The tertiary and secondary structures of alpha and beta globin proteins are very similar, each having eight helical segments. Moreover, one heme molecule is found in every globin chain, and this molecule has a porphyrin ring with four pyrrole molecules linked together cyclically, and bound in the center by an iron ion.

The heme molecule is situated amid helix E and F of the globin protein. The globin chains have subunits of alpha and beta exist which are present in two dimmers attached together tightly. Hemoglobin has amino acids that make alpha helices, joined together by small non helical segments. The helical segments in the protein are stabilized by hydrogen, making them to pull towards each other inside the molecule, and every polypeptide chain folds into a particular shape. The quaternary structure of the hemoglobin forms a tetrahedral figure of four subunits (Natzke, 1998). The folding pattern is made up of a pocket that bonds the heme group strongly.

A matured person has a type of hemoglobin that is tetramer with four subunits of protein known as hemoglobin A. Each sub-unit has similar structures and sizes that are almost equal, and a molecular weight of close to 17,000 daltons. The hemoglobin molecule of an infant contains two gamma and two alpha chains and as the baby gets older, the gamma chains are slowly replaced by the beta chains. Lastly, the chains of the four polypeptides are closely held together by salt bridges, hydrophobic interactions, and hydrogen bond.

Functions
The basic role of hemoglobin is to carry oxygen from the lungs to the rest of the body tissues and then carry carbon dioxide back to the lungs from the body tissues. A single molecule of hemoglobin can carry up to four molecules of oxygen. Oxyhemoglobin is a form of hemoglobin that is saturated with oxygen and the one desaturated with oxygen is known as deoxyhemoglobin (Hsia, 2001). In the lungs, oxygen binds on the oxyhemoglobin and is supplied to the tissues through the blood steam. In the tissues, oxygen binds to myoglobin which is then carried to the mitochondria where it is consequently used for respiration. On the other hand, deoxyhemoglobin carries two molecules and two protons of carbon dioxide to the lungs which then releases it through exhalation.

Hemoglobins ability to receive oxygen molecules from the lungs and later release them in the body is controlled by factors inside the hemoglobin molecule and chemical factors that are external. A major regulator of the ability of hemoglobin to acquire oxygen is the quantity of oxygen itself that is available. After oxyhemoglobin manages to bind a single oxygen molecule, its affinity for more oxygen goes up until its saturated (Midline Plus, n.d). When an oxygen molecule is lost by deoxyhemoglobin, its affinity for oxygen that is remaining is diminished. This kind of regulation is called cooperativity and is crucial for the functions of the hemoglobin since it enables the oxyhemoglobin to transport enough amounts of oxygen to the body tissues, and deoxyhemoglobin to release all the oxygen molecules into the tissues.

Unique structural characteristics of hemoglobin enable the functioning of cooperativity and studies have revealed that the cooperative characteristic is lost when hemoglobin is divided into half. In essence, hemoglobin appears to be an allosetric protein which acquires many shapes and its structure can go through conformational changes depending on environmental conditions. Two different structures that hemoglobin can take include the relaxed structure (R) and the tense structure (T). The R structure has a higher affinity for oxygen while the T structure has a lower affinity for oxygen. The shift from T to R structures depends on the presence or absence of oxygen. Moreover, the ability of hemoglobin to acquire oxygen is controlled by chemical factors that are external such as pH, CO2, and DPG (2,3-diphosphoglycerate) ( HYPERLINK httpBio.davidson.edu t _blank Bio.davidson.edu, 2006).

The Bohr Effect
The pH found in the tissues is lower meaning that it is more acidic than the one in the lungs. Protons are formed when carbon dioxide and water reacts and this results to bicarbonate. There are two functions for increased acidity. First, protons reduce hemoglobins affinity for oxygen, thus enabling it to be easily released in the tissues. In the process of releasing the four molecules into the tissues, two protons are bound by hemoglobin. This is referred to as the Bohr Effect where equilibrium is maintained which is important for the release of CO2 as waste since it cannot dissolve in the blood stream. The bicarbonates ions can dissolve and be carried back to the lungs after hemoglobin binds it (USA Today, 2008). If the excess protons are not absorbed by the hemoglobin, it will become impossible to remove carbon dioxide.

Mutation of hemoglobin
The mutations that occur due to the hemoglobin dysfunction comes as a process that involves the messenger RNA precursor, then it follows that the post-transcriptional processing with methylation, translation, that proceeds through three different phases of initiation, elongation and termination. After all this, there is finally the interaction of the hemoglobin chains that form mature chains. Generally, these mutations that are as a result of hemoglobin disorders are either those consisting of the structural abnormalities and from the reduced globin synthesis.

Those that result from the abnormalities of hemoglobin structure are for example sickle cell anemia. The carriers are generally healthy though they can develop certain problems when in conditions of low oxygen saturation such as deep sea diving or during general anesthesia. The sickle cell mutation involves the change of base of A to T in the second nucleotide of the sixth codon in the beta-globin gene that results in the substitution of the valine for the glutamic acids such as the GTG and GAG. This eventually leads to the formation of a tetramer that is usually unstable in the deoxygenated form. If this continues and the saturation of oxygen goes below 85 percent, then the tetramers form some rod-like structures that cause the red blood cells to become sickle cell (Medline Plus, n.d). The effect of this is the resulting of hemolytic anemia that is being caused by the sickled red cell being fragile and also the occlusion of the peripheral circulation as a result of the clumping together of these cells.

Another mutation is called the alpha-thelassaemia that is being caused by the deficiency of the alpha-globin chain synthesis. Here, the processes involved are the deletion of one or both the contiguous alpha-globin genes being as a result of the unequal crossing over of the homologous sequences of the alpha-globin gene cluster. The individuals that are having this problem are usually asymptomatic with a mild anaemia and hemoglobin levels that are ten to twenty grammes per hundred milliliters (Natzke, 1998). All this leads to the erythropoiesis and increased red cell destruction and finally causes severe hemolytic anemia which leads to the expansion of the bone marrow cavities that finally cause bone deformity and the risk of the pathological fracture.

As a result of these gene frequencies that are definitely high and that have different forms of haemoglobinopathy in the area of high malaria infections, the individuals that are there will have to inherit the alpha andor beta-globin gene clusters. This is by the way of many observations made consistently.

The sickling variety of the hemoglobin gene is related to missense mutation. The molecular disease called sickle cell anemia occurs after mutation alters one area in the amino acid sequence of hemoglobin (Hb) molecule. People who inherit two mutant copies of the beta globin gene suffer from this disease. Linus Pauling a Nobel Laureate (1940s), and Verne Ingram (1950s) showed that the mutation was a result of transversion from thymine to adenine. This leads to the conversion of an amino acid which is close to the end of the beta chain of a persons hemoglobin, from glutamic acid side to a valine.

The hydrophilic side chain which is negatively charged is changed to a hydrophobic side chain leading to the conversion of HbA to HbS. When this occurs, the way in which hemoglobin molecules cumulate at low concentration of oxygen is altered, and the HbS molecules make the red blood cells containing hemoglobin to bend and form a sickle shape. Moreover, sickle cell hemoglobin molecules stick together and form rigid rods which are unable to transport oxygen well, leading to clogged capillaries that cut off blood supply to sensitive tissues like the brain and the heart. The sick individual goes through terrible pain and a possible heart attack or stroke can occur, just because of one nucleotide mutation.

Hemoglobin and sickle cell anemia- Malaria-
There is a greater incidence of the sickle cell malaria and malaria it is often believed that sickle cell provides resistance for malaria. First malaria is being caused by the plasmodium parasite whose life cycle is in the human beings red blood cells, after this the blood cells with the sickle-cell trait break down after infection. The red blood cells that have the trait of sickle cell tend to have low oxygen tension. This parasite reduces the oxygen tension in the blood cells that they infect because they use oxygen for their own metabolism. On the other hand in the case of low oxygen levels the potassium in the red blood cells leak out to be used by the parasite due to the for its development. Therefore, the resistance of the individuals with sickle cell trait to malaria is explained by the increase in immunity. These individuals in the malaria epidemic areas get the parasite of malaria that is introduced in their bloodstreams during their childhood. Because of this association of the individual body with the parasite then the carriers get the immunity against malaria.

Sickle cell anemia results from a mutation in the Hbs gene. Humans have two copies of the gene that code for the normal hemoglobin protein. Mutation in both copies of the gene result in errors in the transcription of hemoglobin protein which result in abnormal mutant hemoglobin. This abnormal form of hemoglobin causes the erythrocytes of the victims of the disease to lose their oxygen and fold into a sickle abnormal shape during intense activity. This results in the interference in their flow in blood vessels causing manifestation of the symptoms of the diseases in form of pain, swelling and tissue damage which can be lethal. Mutation in one copy of the gene does not result in the complete diseases and victims are called carriers and suffer less severe symptoms. Researchers have revealed that mutation in this gene grants resistance to malaria especially in areas that are hit by malaria like the tropics where 40 of population has at least one mutant copy of the Hbs gene. This shows that the mutant gene has naturally selected to confer resistance to malaria in these regions. The erythrocytes of the victims of this disease fold into their sickle abnormal shape when they are infected by the malaria protozoan parasite. This abnormal shape makes them to be filtered out of the bloodstream by the spleen as it passes through due to their shape. Therefore, the parasite is eradicated together with the abnormal red blood cell. This lethal mutation in the Hbs gene that cause sickle cell anemia is an example of mutations that are sometimes beneficial because it confers a survival benefit against malaria

Viruses are biological particles which are causative agents of various diseases and examples of which are the herpes simplex virus, adenovirus, and vaccinia virus. Infections are caused by viruses only under specific conditions wherein they are situated inside a living host cell, an event which accounts for its intracellular nature of existence and infection. In addition to this, viruses tend to maximize the usage of the cell components of the host organism in order for them to attain a high copy number inside the hosts body system. To accomplish such kind of activity, viruses need to multiply by replication and move the replicated viral particles into the different sites of the hosts body and this activity requires the utilization of the intracellular energy and components of the host such as the microtubules and dynein-dynactin complex. The aforementioned viruses, herpes simplex, adenovirus, and vaccinia virus, all utilize the microtubules and dynein-dynactin complex of the host to initiate replication and continue with the infection cycle. Furthermore, cell-to-cell spread of viruses from infected cells to non-infected cells is facilitated by the usage of diffusion and cytoskeleton movements within the host cell where the latter accounts for the transfer of relatively small viruses and the latter explains for the relocation of the viral particles through the help of actin-based motility as initiated by the hosts cytoskeleton. In order to further explore the topic of actin-based motility of viral particles, the goal of this paper is to focus on the discussion of the mechanism by which vaccinia viruses are able to elicit cell-to-cell spread. The discussion is aimed to center its attention on the exploration of the tyrosine phosphorylation of the intracellular mature virus (IMV) as explained by the activity on A36R membrane protein, WASP-interacting protein (WIP) and N-WASP, and event which results to the production of long, virus-tipped projections at the plasma membrane of the host cell which facilitates cell-to-cell movement of vaccinia viruses. The significance of this study is evident on the fact that the vaccinia virus constitutes the best-characterized model of cytoskeleton-driven viral motility and a demonstration of the additional features of these microscopic activities is important in the enhancement of present knowledge on the nature and dynamics of viral particle behavior and activity so as to prevent and control the proliferation of detrimental to lethal viral disease like the smallpox, a disease that is caused by the family of vaccinia virus.  

The experimental process employed to accomplish the goal of this research paper is composed of seven steps and these are the generation of stable GFP--actin cell lines, pEL vector constructs, preparation of the antibodies, infection, pEL-driven expression and immunoflorescence on fixed preparations, live cell imaging, analysis of the images produced, and, the construction of recombinant AR36-YdF vaccinia virus. The first step, explains the amplification via polymerase chain reaction methods of the chicken cell lines and human sarcoma cells that served as the host cells of the viruses while the second step characterized the amplification of the F13L and A36R open reading frames of vaccinia virus which were used as the vector of infection. The third step, preparation of antibodies, was accomplished by using rat monoclonal antibodies, an event which is essential in the visualization of the actin, through the usage of the anti--actin antibody AC-74, and microtubules, through the usage of pactin-mb5tubulin-EGFP. The fourth step, on the other hand, is comprised of the vaccinia infection on the host cell lines and subsequent performance of immunofloresence procedures to view the infected cells and viral particles. Live cell imaging is accomplished by utilizing a specialized camera that was able to detect the volume imaging and cell plane viewing and this step was followed by deconvolution and image reconstruction to better scrutinize the features of the images and manifest virus movements via microtubule assistance. The last step, construction of recombinant A36R-YdF vaccinia virus, was accomplished by harvesting the freeze-thawed recombinant vaccinia particles and confirming the fidelity of the recombinant through PCR methods, a step which marked the verification of the observed experimentally observed importance of actin-based viral movement for vaccinia particles.

Results show that actin tails have originated from the plasma membrane through the help of the cell-associated envelope virus (CEV) and this is in contrary to the previous observation that intracellular enveloped particles (IEVs) have nucleated actin tails. This observation is supported by the fact that electron microscopy was able to produce images that explains the distinction of IEVs from CEV at the tip of actin projections, and event which caused the confusion of the nature of actin sources. Despite the fact that researchers cannot rule out the possibility that the formation of actin filaments helping vaccinia virus during cell-to-cell spread is participated by IEVs, the notion that the mechanism by which actin-based movement of vaccinia virus is more obviously allotted to CEV is an important finding in this paper. This paper has disproven the previous assumption that actin polymerization is initiated at the periphery of plasma membrane and often with associated CEVs at the tip of the projections because it was confirmed by imaging that actin filaments only form close to the periphery of the plasma membrane. It was also clarified in this paper that actin polymerization is induced on the inner cytoplasmic surface of the plasma membrane through the help of the A36R, an integral membrane protein. Moreover, imaging analysis revealed that high quantity of virus release is achieved by vaccinia particles while maintaining low CEV retention at the plasma membrane. In general, this paper confirmed the idea that vaccinia virus makes use of microtubules and cytoskeleton to enhance its infection process.

Any changes that alter the self perpetuating nature of the world are termed as a global change. The global changes interfere with the global fluid envelopes that include land, the oceans and the atmosphere. Global changes are experienced all over the world. These global changes include changes in the atmospheric composition of gasses, the decreasing ozone concentration, the climate change and their consequences. The climate changes and other global changes have resulted into unpredictable weather conditions and widespread famines, changes in the land use, invasion of biologically sensitive resources and changes, increased ultraviolet radiations from the space and general changes in the atmospheric compositions. All these changes are a threat to the global biodiversity.

Global change and Biodiversity
The global warming among other global changes that have been experienced over the last few decades has raised major concerns on the future of the global environment. The ability of the earth to support and sustain the biodiversity is at stake due to the global changes that have been experienced over the last century. The changes are a threat to the human race as well as general biological diversity of the world. Scientist argues that with the current trend, the earth will not be able to sustain the human civilization in the next few centuries. This is evident from the increasing concentration of carbon and other greenhouse gases in the atmosphere, the increased temperatures as a result of global warming, melting of the ice sheets and submerging of the sea line. The rate at which animal and plant species are getting extinct is also worrying.
 
There is no doubt that many of the global changes that are being experienced today are man driven, either directly or indirectly. The global changes may either be biophysical which affect the physical world as well as the biological diversity or they may be social and economical changes that affect the lives of human beings and their interaction with the physical and biological world. These changes includes the general alteration of the global biological fabric, flows and distribution of chemical elements such as carbon, sulphur, nitrogen and the metals and the global energy balances. These changes are direct impacts of changes in the land use, changing the land cover, industrialization and globalization, increased population, increased use of fossils oils and encroachment of natural resources among others.

Antropocene also has been used to explain the global changes that have been experienced throughout the history of the earth. This approach looks at the Holocene and the impacts of human society development on the environment. Holocene is the periods in the history of the world that came after the glacial geological period. During this period, there have been changes in the activities of the human kind that have had a big impact on the earth and as consequently led to global changes. Important advancements in this period includes the invention of fire, development of agriculture, invention of fossil fuel energy and machines, industrialization and the explosive increase in the world population in the 19th and 20th century. During the Holocene era, human activities have become the driving force on the morphological and geological changes in the earth. Mans activities have modified the physical and biological aspects of the earth.

Mans effect on the earth system cannot be quantified. The power of man on earth has been compared to the power of earth itself. It is true that man has either inhabited or visited all parts of the world. Man has even extended his influence beyond the earth releasing communication gadgets to the space and landing in the moon. Biologists and geologists identified the great influence of human kind on the global environment in the early 20th century in the rise of industrialization. Over the years, these human influences on the environment have attracted a lot of attention among biologists and environmentalists. The changing human activities in the world are directly responsible for the loss of biological diversity. Unless measures to reduce the influence of human activities on the physical and biological fabric are controlled, the globe may be unable to support the biological diversity in the near future.

Since the industrial revolution, the increased carbon gases concentration in the atmosphere has been the greatest threat to the biological diversity. The increased carbon dioxide and other greenhouse gases concentration in the atmosphere over the last century are well documented. The increased dependency on fossil fuels as a result of massive industrialization in the 20th century is the basic cause of the increased carbon dioxide concentration in the atmosphere. Another factor that has also played a major role is the encroachment of natural forests. The rapid increase in population has created the need for more land for food production through agriculture as well as for human settlement. This increased clearing of forest has disrupted the self perpetuating carbon cycle.

Scientific analysis that have been carried in the second half of the 20th century indicated that the concentration of carbon dioxide increased from about 315 ppm in the mid twentieth century to about 350 ppm towards the end of the century. The analysis also indicated that the rate of increase in the concentration increased over the interval. The increase in the carbon dioxide concentration being experienced in the modern time is estimated to be equal only to the increase experienced in the glacial interglacial era which resulted into global changes and affected the global biological diversity significantly. However, the historical changes in the concentrations of gases in the atmosphere were as a result of natural causes while the current changes are as a result of human causes.

Recent research indicates that the increases dependence of the world economy on fossil fuel is the primary cause of the increased carbon in the atmosphere. The encroachment of natural forests for agriculture, settlement and industry and infrastructure development and changes in land use has been rated as the secondary causes of the carbon increase. The increased carbon dioxide from burning fossil fuels has altered the natural balance between the isotopes of carbon in the atmospheric carbon dioxide. Carbon dioxide from fossil fuel is carbon -13 depleted and has thus diluted its concentration in the atmosphere. The result has been increased concentration of carbon-12 and carbon-13 which has adverse effects on the food chain. Any alteration that affects the food chain is a threat to the global biological diversity. The increased carbon dioxide has had negative impacts on the ozone layer and general reduction in air quality especially in industrial areas and busy cities.

There are other gases that have been associated with global changes that threaten the ecosystem of the world and the biodiversity. Chemicals such as the deadly chlorofluorocarbons in the ecosystem have increased significantly. The concentration of methane gas in the atmosphere has increased tremendously over the years and scientists have estimated that its concentration has doubled over the last two and half centuries. This has been as a direct consequence of the increased agricultural and industrial activities over the same period of time. Nitrogen imbalance as a result of increased use of nitrogenous fertilizers in agriculture has also been reported with an increase in the concentration of oxides of nitrogen in the atmosphere.

The immediate effects of the increased concentration of greenhouse gases in the atmosphere are the climate change the world is experiencing today. It is one of the global changes that have impacted negatively on the ecosystem leading to loss of diversity. More solar radiations are reaching the earths surface as a result of the depletion of the ozone layer which acts it as a filter. Some of the impacts of climate changes are the increased global temperatures, unpredictable weather, increased floods and drought. For over three decades, the impacts of greenhouse gases on the ozone layer have been known to the scientists. The gases have been known to catalyze the break down or react irreversibly with the ozone layer leading to its depletion. The increased radiations from the space have adversely affected plants, animals, human beings and the world ecosystem in general.

Scientists have also reported an increase in carbon in the soil which affects the ecosystems in the soil and the atmosphere as a result of increased decomposition. There are numerous species of microorganisms that have been found in the soil. These microorganisms play an important role in maintaining the quality of soil. The terrestrial ecosystems have also responded negatively to the increased concentration of carbon gases in the atmosphere and the resultant climate change. This has resulted into permafrost thawing and the associated decomposition of frozen materials. This occurs as a result refreezing of organics materials which have resulted into increased carbon into the ecosystem as more frozen carbon undergoes microbial decomposition.

The increased temperatures are continuously and catastrophically exposing the frozen carbon to microbial activities which is estimated by scientists to be up to twice the atmospheric carbon. The thawing of the permafrost combined with other impacts of the climatic change is slowly turning life on earth to extinct. The changes in the plants growth rate as a result of increased carbon, and the energy changes have not shown any sign of compensating the increase in carbon concentration as a result of microbial decomposition of thawing permafrost. Though the process is slow, in the long run, the increased carbon will be catastrophic and will affect the ability of the earth to support the diverse biological ecosystem.

The rate at which different mans activities which have led to various global changes is causing animal and plant species to become extinct is alarming. Scientific research indicates that all biological species in the world are ephemeral under natural conditions where episodes of mass extinction occur rarely and after thousands or millions of years. It is estimated that a species exists in the ecosystem for an average of ten million years before becoming extinct naturally. Human activities have however affected the biodiversity of the world where the rate of extinction has been raised several folds above the natural background rate. This increased rate is directly as a result of changes in the land use and encroachment of natural ecosystems, biological invasions and the increased environmental degradation.

Scientists estimates that if the current trend at which species are becoming extinct is maintained, most of the plants and animal specials will disappear from the ecosystem in the next one or two centuries and the biological diversity enjoyed in the world will be lost. The world will experience mass extinction that has never been experienced in the earths history since the Cretaceous Tertiary Boundary. Man has intentionally or inadvertently invaded the biodiversity for many years. He has eliminated some species in the ecosystem while at the same time introducing others altering the natural balance. The wave of globalization has increased the mobility of humans. As the human becomes mobile, the plant and animal spaces have also become more mobile leading to biological invasion. The long term effect of this mobility is the loss of biological diversity as the biota of the whole planet become homogeneous.

Conclusion
The realities of global changes are becoming more evident in the world. It could have been difficult to explain the impacts of high concentration of greenhouse gases half a century ago, but today, the impacts are almost obvious. There are many global changes that have happened as a direct impact of the human activities in the globe. Moreover, many of the global changes are intertwined. For this reason, biological diversity has been threatened by the global changes that are influenced by mans activity. The biodiversity is being lost at an alarming rate.