Gene Flow: Causes and Barriers

Gene Flow: Causes and Barriers Variation of inherited traits in the section of individual organisms over a period of time is referred as evolution. The major renowned sources of variation are gene flow, genetic recombination and mutation. Gene flow that is also acknowledged as gene migrations is the genetic alleles exchange within populations by migration of gametes, spores and individuals of the same species. This is common in species through crossbreeding, migration and cross pollination which yield hybrid organisms. Movement of genes is often carried out by human being and wind. When people move from one town or country to another and carry with them plants to experiment if they can grow in their new location gene variation commence. Differences in gene flow across populations depends on the type of organism, populations of inactive organisms tends to be more isolated from each other than population of actively moving organisms. This paper will examine gene flow as an aspect of evolution biology and provide a d eeper understanding of its benefits to organisms. Mobility in gene flow One of the principal factors contributing the flow of genes between different populations is their movement habit. Plant population compared to animal population appears to be sedentary, hence, animals have high rate of experiencing gene flow. Migration and emigration of populations can reduce genetic differences within that particular group (Beurton, Peter, Raphael Falk et al 224). Through emigration, genes are carried away by the ongoing individuals to a new destination, whilst migration brings on board new genes to an existing gene pool. These processes are activated by perpetual diffusion and mixing of genes of a sexual population. Barriers to Gene Flow Human growth and advancement in technological world has not been without its cons to gene flow. This is a major obstacle to gene flow, especially in its many artificial and permanent development of the landscape. A structure like the Great Wall of China has hinder movement of many organisms and relocation of alleles of genes of indigenous plants population (Lewin 95). Another behavior that prohibits gene flow is the fencing of a game park where insider animals are restricted from meeting others from another park. Vast human progress and occupation can wipe out or partition ecosystems into a desert or secluded islands resulting to lessening genetic variation of the populations imprisoned there. In the efforts to facilitate gene flow scientists are increasingly crafting new ways to connect to these isolated species as away of maintaining viable genetic variation. The other distinguished barriers are the natural barriers that halt or slow the rate of migration of genes among populations . These are oceans, impassable mountains, hills and large and wide deserts that exhibit great challenges for animals movement. This hindrances leads to loss of genes in a population as fertile population are barred from meeting the weak or other strong ones (Beurton et al 124). These barriers in human population have created suspicion and tension among races to an extent of tribal animosity. Conducted studies reveal that sex chromosomes (X and Z chromosomes) are affiliated to reproduction and sex genes (Lewin 88). These genes are a factor in the progression of post zygotic isolation especially in hybrid sterility. It has been noted empirically that strengthening of zygotic isolation does occur in certain conditions. Recombination between alleles is a significant factor that has been identified to be opposing reinforcement. Connections between genes that affect mating and those that affect hybrid fitness plus sex chromosomes have the likelihood of boosting the process of hybridizing species. These ideas fall short of extrapolating whether essential forms of non-adaptive effect of divergence with no gene flow are stagnant or they increase. As a result of this we discover that there exists co evolution of zygotic barriers to the flow of genes. Gene flow in action The lives of species is involves a lot of movements in search of satisfaction and fulfilling hierarchy of needs. Thus, migration has become a significant force of restructuring genetic variation. In the contemporary globalization characterized by wide dispersions of humans in search green pastures and mates gene exchange is take place fast. There are now inter-racial marriages aiding much generating patterns of hereditary variations. Migration can occur to a mass of people due war or search of resources and food or to an individual as a result of displacement or personal drive to explore. Large scale migration of people leads to accumulation of mutations and as a result population diverges as there is genetic drift. Individual movements in a small geographical area enhance genetic variation between populations. These migration behaviors have distinctive effects on population structure with each having its methodological challenges. Gene flow accelerated by intermarriage between national or state communities occurs frequently within a short time period. It remains a challenge to determine temporal control and spatial control of historical human migration. Geographical sampling is a costly exercise, hence, to determine geographic scope of a specific event advanced genotyping technologies are used as they are economical. Determining temporal control which is when gene flow has occurred is even more challenging; DNA studies are examined to come up with resolution pertaining human mobility. New methods are underway to provide conclusive sequential bounds on flow of human genes using genetic data that will be analyzed to show human gene flow. To discover historical movements researchers use genetic markers like mitochondrial DNA and the Y chromosome as they are highly thought to be mainly instructive genetic markers. To study human history using these markers one has to understand that Y chromosome is passed from a f ather to sons while mitochondrial DNA is passed only from mother to off springs. This distinctive mode of transmission makes it easier to study human descent. Due to high rate of random genetic drift in these systems Y chromosome and Mitochondrion DNA have been found to have uncertainty. Their records show biasness towards the sex-specific migration of women and men as they are small loci representing large region of human genetic variations (Slarkin 327). Nowadays, multiple markers can be screened across human genome due to rapid progress in use of genotype technologies. Hence, to determine if two populations have similar genetic variations has become simple. However, it requires advanced modeling and inferential statistics to enumerate and establish the amount of gene flow between them. Gene flow from Neanderthals have made scientist to meditate and compare entire genomes. Complete genome sequence of Neanderthal has been sequenced by some scientist. Previously only mitochondria DNA were accessible from Neanderthal as they occur in numerous copies per cell which make it difficult to mine DNA from primeval remains (Barton Bengtsson 360). In this conducted study there was no trace of gene flow between Neanderthal and human being albeit this research was not conclusive as Mitochondrion DNA could have been mislaid through genetic drift. A complete combination of genome sequence from three Neanderthal creatures has been led by Green and colleagues through use of advanced new technology of sequencing. In contrast to mitochondrion DNA there are data sets that show existence of gene flow from Neanderthal to modern human being. It has been identified that non-African descendant have at least 13 genetic regions that originate from Neanderthal siblings. Since these regions are not present in Africans descent, this is thus a sign to show that gene flow had occurred from Neanderthal to modern people as it is assumed some ancestors had left Africa around 50,000 years to look for other destination in the rest of the world (Servedio Kirkpatrick 766). Conclusion An increase or decrease of a population affects gene pool frequencies as gene flow will have high chance to take place in a densely populated area while there will be minimal changes in a sparsely populated area. For example if all black people were to leave America, the next generation of humans would probably have few or no blacks. This study has revealed that gene flow can occur without migration especially in circumstances where people pays a visit to particular place and mate with natives even though they will eventually go back to their place. In this case, genes are transferred across those populations and the resulting generation is hybridized. Gene flow occurs between species when segment of DNA are carried by viruses in their routine invasion of cells of plants and animals. Although this mechanism of transfer is seldom, there exist documented evidence for some species of microorganisms, mammals, reptiles and insects. Human beings have not been left behind in this process; there is a high probability that 40-50% of DNA sequencing might have been carried out by viruses (Slarkin 420).

University Success

Grand Canyon University strives to support student learning by creating an online community. A â€Å"community† feeling inside an online course can help me as well as other students stay motivated. Online classrooms have the same characteristics as a traditional classroom; however, the class instructors direct course materials through a Grand Canyon University online portal. The course instructor presents topic-based questions to the students in the classroom forum that allow collaboration of student and instructor thoughts, debates, and experiences. The online interaction between classmates as well as instructor creates a virtual community where classmates and instructor can rely on each other while helping each other to stay motivated. The online classroom relies on collaboration between students and instructor in order to promote successful learning experiences. Collaboration in an online classroom consists of student responses to the instructor’s questions. As students post their individual thoughts, other students respond to them adding their own perspectives, experiences, and knowledge. Once the conversations volley back and forth thru ought the course’s main forum true collaboration begins. According to the text University Success E2, â€Å"The keys to avoiding isolation are communication, collaboration, and networking† (Grand Canyon University, 2012). It is evident that collaboration in both an online and a traditional classroom is dependent on instruction, participation, as well as feedback and it is most effective when students participate several times a day. It is imperative that students are aware that they are responsible for their own collaboration by participating in interactions with other classmates and the instructor through the class wall, individual forum, e-mail, or chat rooms. A major advantage that comes from effective collaboration is the skills that students gain from being actively involved in the classroom that is necessary for almost every career. My future career as a teacher depends on effective collaboration among my peers and me as it ensures professional development and school improvements. Some students use collaboration to network beyond the classroom. For instance, networking with family, friends, coworkers, Twitter, Facebook, or other discussion forums opens up portals to further collaboration with non-GCU students. Further collaboration expands the students’ minds as well as offers more information or perspectives. Furthermore, networking is beneficial to professionals in any career field because it expands professional knowledge, keeps professionals abreast of new business trends, offers career and personal opportunities, as well as provides business leads.

Gantt Chart for Execution of House Construction Essay

The activity of house construction involves many stages which are spread over many months. The case study example taken for the preparation of Gantt chart is selected as it involves various stages and there are many people involved in different activities. These activities are interdependent on the performance of various work groups and can get delayed if not planned and executed timely. Thus I present a Gantt Chart that will assist and ensure effective working in order to obtain the end result as planned. Explanation of Gantt Chart (refer appendix) The overall activity has been planned for a time span of 9 months. The activities have been classified as follows Excavation (A) : This is the first stage where excavation for the house columns needs to be carried out. The lead time for this activity is one month. This is a process which is labor intensive and needs to be completed as per the architectural drawing. Other activities cannot be started before ensuring accuracy of the excavation work as the structure cannot be modified if desired at a later stage. Hence activity B , RCC cannot start before 100 % completion of activity A. In case during this phase it is realized that any delays could be caused in reaching the first milestone then additional workforce or earth moving equipment needs to be outsourced. RCC (B) (Reinforced Cement Concrete) : The lead time for this activity is three months. Once excavation is complete the next stage is of RCC which involves making columns and beams of the house. Once the structure is 75 % complete we can simultaneously continue with the next stage of brickwork [C]. The achievement of this milestone will not hamper activity C but due caution has to be exercised that the activity gets completed by the fourth month form the project starting date as it is the start of activity D and E. Brickwork (C) Along with brickwork the other activities Electrical (D) and Plumbing (E) also need to be commenced upon the completion of stage B and 50 % of stage C as the electrical pipes and fittings need to be covered inside the walls. Similarly toilets and kitchen requires plumbing to be done simultaneously. If the activity deviates from its planned lead time of two months then activity D, E and F will need to be carried out at an increased pace than its actual to cover up for the lag time. Electrical (D)and Plumbing (E) These stages can be executed simultaneously as they are not interdependent on each other . Once these are complete we can move on to the next stage. Plastering (F) After completion of electrical and plumbing work we can start with the internal plastering activity. However external plastering can be carried out when 50 % of stage D and E are complete. This is the third milestone. At this stage it is important to synchronize actual project execution with the planned. Tiling (G) Once plastering is 100 % complete then we can move on to Tiling & Flooring work Painting (H) This is the final milestone to be executed after 100 % completion of activity G . Conclusion: Gantt chart gives a clear picture of the stages and helps in noticing any deviations and corrective steps can be implemented which in turn will not disrupt other schedules and help in achieving desired results in a cost effective and efficient manner. The case for buy Vs make is indeed a matter of individual capacities and judgment in the said example. By choosing to make as in the above case the maker gets freedom of choice and taste to suit his own needs. If activities are carried out with due diligence the project would be cost effective. Reference : Gantt Chart- Wikipedia, 19 October 2008, < http://en. wikipedia. org/wiki/Gantt_chart>

Essay on Alzheimers Disease - 1266 Words

An Exploration of one of the Most Mysterious Diseases nbsp;nbsp;nbsp;nbsp;nbsp;Alzheimer’s disease, named after Dr. Alois Alzheimer, is a disease that is on the rise in America and the rest of the world. People should learn as much as they want about this disease, because as you age, your chances of becoming an Alzheimer’s Disease, or AD, patient increases. It is estimated that approximately 3 percent of Americans between the ages of 65 and 74 have the illness, and more than half of all people over age 85 have the ailment. nbsp;nbsp;nbsp;nbsp;nbsp;AD is a form of dementia, a disease, that according to the Alzheimers Disease Education amp; Referral Center is defined as: â€Å"†¦a group of symptoms that are caused by changes in†¦show more content†¦Since AD is a human disease, animal subjects are also unavailable to use for examination of the sickness, but they can be genetically engineered to have mutant genes that cause them to have amyloid plaques, and, although they do not obtain AD or nerve failure, because they do not have neurofibrillary tangles, they do show memory and learning problems as they grow older. There are ways to put the blame of AD-like symptoms on other problems, like a stroke or brain tumor, and that is by using Computerized Tomography or Magnetic Resonance Imaging. (Know respectfully as CT and MRI) These brain imaging devices are useful, yet they still cannot identify plaques and tangles. nbsp;nbsp;nbsp;nbsp;nbsp;The symptoms of AD are caused by the plaque tangles in the parts of the brain are known as hippocampus and the cerebral cortex, which both manage memory, language, and mental processing. The frontal cortex also is affected. This is what, in the normal brain, causes one to daydream. Other parts of the brain that have been affected include the cortical and sub-cortical regions, which have been linked to the control of happiness and euphoria, and are affected when one uses drugs that alter these senses, such as marijuana. Also, those people who are constantly under negative stress are likely to develop memory loss, if they are fortunate and don’t get AD as well. For this reason, as stated later inShow MoreRelatedAlzheimers Disease1334 Words   |  6 PagesAlzheimer’s Disease Brittany Mathis HCS/245 July 14,2013 Tynan Weed Abstract Alzheimer’s has many causes and affects each patient differently. There have been studies done that have found that older African American’s are more likely to develop Alzheimer’s than older whites. A cause of Alzheimer’s has not been completely identified yet, but genetic and environmental factors are known to increase the risk. While we all know that Alzheimer’s is a complicated disease there areRead MoreThe Disease Of Alzheimer s Disease1421 Words   |  6 Pagesengulfed by a mysterious disease. The neurons being cut off and destroyed by two abnormal structures. First memory is affected gradually getting worse. Then one is unable to think properly, reason, and lacks of self control. Gaps are formed in the brain s ventricles, due to the amount of dead tissue. In the end, it will lead to death. 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Alzheimer’s is a progressive destroying of brain tissue that primarily strikes people over the age of 65. Brain functions such as memory, comprehension, and speech deteriorate. The term first introduced by Dr. Alois Alzheimers in 1906. Memory is lost first. As days passes, attention tends to distracted, simple calculationsRead MoreThe Disease Of Alzheimer s Disease1677 Words   |  7 Pagesone thing Alzheimer s cannot take away, and that is love. Love is not a memory - it s a feeling that resides in your heart and soul.† (Fade to Blank). The human brain is a remarkably complex organ that processes, stores, and recalls information. â€Å"Alzheimer s disease (AD) is a slowly progressive disease of the brain that is characterized by impairment of memory and eventually by disturbances in reasoning, planning, language, and perception. 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Alzheimer’s is a disease that many individuals suffer with each year, but yet with all the advancements in modern medicine we still have no cure for it. There are differentRead MoreThe Disease Of Alzheimer s Disease1385 Words   |  6 PagesThe disease stem cells could fix is called Alzheimer’s Disease (AD). The reason I chose this topic is because I have seen first hand how badly someone who suffers from Alzheimer’s Disease is affected in their daily lives. This disease completely takes over their lives and they turn into a completely different person who can hardly function. AD is very tough on the loved ones of the person suffering from it because that person, most of the time has no idea what is going on or who their loved onesRead More Alzheimers Disease Essay1174 Words   |  5 Pages Alzheimer 1 nbsp;nbsp;nbsp;nbsp;nbsp;It is inevitable that eventually each of us will grow old and begin to face more and more health problems as our age rises. 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