Why are conservationists concerned about gene flow?

Why are conservationists concerned about gene flow? This essay intends to look at how the process of gene flow can be of concern to conservationists, by examining some specific examples that emphasise the problems that often result from it. The essay will begin with a brief description of what gene flow is, before explaining why it can be a problem. It will then go on to discuss an example of naturally occurring gene flow - in blue tits among Southern France; followed by an example of gene flow resulting from human activities - that of the use of Genetically Modified Organisms; that result in concerns from conservationists. The essay will then use the example of a pocket gopher species to show how diverse a species can become when gene flow is absent. The essay will conclude by suggesting possible ways of reducing the negative effects of gene flow and explaining why, despite there being possible situations where gene flow could have positive influences, as a whole it can only ever be seen as a negative process from the conservation perspective. Gene flow is one of the four generally accepted processes that lead to evolution, along with mutation, genetic drift and natural selection. While the latter two act to change the frequencies of alleles that already exist in a population; gene flow, along with mutation, can actually act to bring new alleles into a population. Gene

  • Word count: 2171
  • Level: University Degree
  • Subject: Biological Sciences
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Explain how the action potential is generated and is transmitted along the axon. Include information about the effect of myelin on the speed of transmission.

. Explain how the action potential is generated and is transmitted along the axon. Include information about the effect of myelin on the speed of transmission. 655 words The brain and the spinal cord form the central nervous system (CNS). The CNS processes information using millions of nerve cells (or neurones). In order to understand their function and process, a description of the neurones and their environment seems necessary. This will lead to the second part which will cover the neurone's actual action potential generation and transmission. Neurones are constituted of an outer membrane, a cell body (or soma) and a nucleus. These characteristics are common to all body cells. Nevertheless, other fundamental features are needed in order to respond to environmental changes: the dendrites that surround the soma and receive nerve impulses. The axon, connected to the soma by the axon hillock, is composed of myelin and nodes of Ranvier, through which the impulses pass. Finally, the impulses reach the axon terminal, and through the synapse, get transmitted to the next neurone. The neurone's resting membrane potential represents its stability, when not stimulated or firing. The cell's charge is -70 mV, the cell is negatively charged whereas the outside is less. The membrane controlling ions moving in and out the cell through ion channels using ion pumps (sucking in or

  • Word count: 726
  • Level: University Degree
  • Subject: Biological Sciences
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Comparison of the structural and functional specialisations of cells lining the stomach with those of the cells lining the small intestine.

Page 1 Comparison of the structural and functional specialisations of cells lining the stomach with those of the cells lining the small intestine. The specialised cells lining the stomach and small intestine vary in structure and function; however, they are similar in the fact that they are both involved in the digestion process. The stomach is a j shaped organ with a wall of muscle which has lots of folds called rugae to enable the stomach to expand when food is present. There are three types of specialized stomach cells that are located in the glands of the stomach lining which is called the mucosal epithelium. These cells produce various gastric secretions necessary for the breaking down food into a soup like liquid called chyme. When this is complete, chyme is passed via the pyloric sphincter into the small intestine which continues digestion and absorbs nutrients into the blood stream or fats into the lymphatic system. The small intestine is approximately 7 metres long and is divided into three parts; the duodenum, jejunum and ileum. Its wall consists of 4 layers; the outer covering called the adventitia, muscularis externa, submucosa and mucosa (see diagram 1). The submucosa is a layer of connective tissue where blood and lymph vessels, glands and enteric ganglia are present. The enteric ganglia is a group of neuron cell bodies that stimulate the production

  • Word count: 1138
  • Level: University Degree
  • Subject: Biological Sciences
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What is HIV?

HIV/AIDS Srabonti Ali The world is plagued by the HIV infection which almost always precedes AIDS . If you are HIV positive, that doesn't mean you have AIDS. However, having AIDS means that you most definitely are HIV positive. HIV or Human Immunodeficiency Virus, basically breaks down your immune system until it eventually cannot function properly anymore. AIDS (Acquired Immune Deficiency Syndrome) never really kills anyone, instead it is a disease like pneumonia or something similar that the body cannot fight because its immune system is shot. (1) The first reported case of AIDS in the United States was in 1981. Nearly 900,000 American citizens are have the HIV virus and about 600,000 Americans have the AIDS virus itself. (3)HIV and AIDS are rapidly growing throughout not only the nation, but the entire world. The most common way to get infected with HIV is through sexual contact with an infected person. Other ways of getting infected are through intravenous needles, blood transfusions. Also, sometimes a pregnant mother can pass on the infection to her fetus before it is born. After the baby is born it is also possible for the baby to get infected through breast-feeding. (1) Most people do not have any distinct symptoms early on. Two months after the first exposure to the virus infected persons may experience flu-like symptoms such as fever, headache, depression and

  • Word count: 750
  • Level: University Degree
  • Subject: Biological Sciences
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Water Strss on Plants

Simulated Water Stresses on Early Plant Development Aim Rationale Results Interpreting Conclusion Appendix I - Plan Appendix II - Trial Plan Bibliography Abstract: As evidence for global warming continues to accumulate, various regions of the planet are already succumbing to drought - causing crops to fail and leading to widespread famine. Understanding the limits of a crop's water tolerance, and how minute changes in water concentration in soil can affect plant growth could be useful in predicting the future success of crops which may undergo water stress. Aim: To investigate water

  • Word count: 4898
  • Level: University Degree
  • Subject: Biological Sciences
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Transposon as tools for genetic engineering

Genomics Summer Semester 2011 Evaluation Essay Dmytro Dvornikov Genomics Summer Semester 2011. Evaluation essay Transposons have been widely used as genetic tools to study many model systems. However only recently have they been used in mammals. Why? Discuss the recent applications of transposition to mammalian systems and consider the advantages and disadvantages of transposition compared to other genetic methods. Abstract ______________________________________________________________________________ For decades transposon-based mutagenesis and transgenesis were used in invertebrate model organisms such as D. melanogaster and C. elegans. This approach offers numerous advantages over conventional methods of viral transduction or non-viral techniques. However, up until recently such methods were not available for vertebrates. Only after an extinct transposable element Sleeping Beauty (SB) was recovered from fish genome in 1997 situation has changed drastically. SB proved to be efficient in somatic, germinal and embryonic stem cells of different vertebrate model animals. Sleeping Beauty was found to be an indispensable tool for loss-of-function and cancer screens, generation of virus-free induced pluripotent stem cells (iPSCs) and human gene therapy. Further development of SB and other transposon systems in vertebrates will help to fill up the gap existing in

  • Word count: 2079
  • Level: University Degree
  • Subject: Biological Sciences
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Methods and Criticism of Cloning and Genetic Modification

Biological cloning can be defined as the creation of one or more genetically identical animals by transferring the nucleus of a body cell into an egg from which the nucleus has been removed (S. Ignacimuthu; 2009). Dolly was the first mammal to be cloned from an adult somatic cell using the process of somatic cell nuclear transfer. She was cloned by Ian Wilmut and colleagues at the Roslin Institute in 1996. Somatic cell nuclear transfer refers to the transfer of the nucleus from an existing organism into an enucleated oocyte. Different techniques are used in somatic cell nuclear transfer. These are The Roslin technique and Honolulu technique. The Roslin Technique was used to create one of the world’s most famous clones, Dolly the Sheep. The cloning of Dolly was a breakthrough in several ways. It demonstrated that the full genetic complement of somatic cells derived from adult animals could be reactivated well into the chronicle life of the cell ( http://www.roslin.ed.ac.uk ). Researchers took mammary gland cells from an adult Finn Dorset sheep, and grew the cells in tissue culture. Using the tissue culture, they made sure that the cells didn’t have access to specific nutrients so they couldn’t grow and divide. This was achieved by placing the cells in a salt solution and inducing a state of hibernation by starving the cells, providing just enough growth factor to keep

  • Word count: 2718
  • Level: University Degree
  • Subject: Biological Sciences
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MonoMUSCLES AND NERVES lab report

Practical 1 MUSCLES AND NERVES A. Histology of Muscle tissue Sample: B Type: Skeletal Muscle Description: Long, striated cells with multiple nuclei Common Locations: In Skeletal Muscles Function: Contraction for voluntary movements Sample: A Type: Smooth Muscle Description: Long, spindle-shaped cells, each with a single nucleus Common Locations: In hollow organs (e.g. stomach) Function: Propulsion of substances along internal passageways Sample: C Type: Cardiac Muscle Description: Branching, striated cells fused at plasma membranes Common Locations: Wall of heart Function: Pumping of blood in the circulatory system More photos in fig1. B. Heart Structure . Right and Left Coronary Arteries Left Coronary Arteries Right Coronary Arteries Diameter Greater Smaller No. of Branches More fewer Length Longer Shorter Explanation It carries blood to the left part of the heart, including left atrium and left ventricle, which pumps blood to the systemic circulation. Greater diameter and more branches of the Coronary Arteries could bring more oxygenated blood to the cardiac muscle in order to carry out forceful contraction. It carries blood to the right part of the heart, including right atrium and right ventricle, which pumps blood to the pulmonary circulation. The distance traveled by the blood they pump out is shorter. Mild contraction is needed. Smaller

  • Word count: 570
  • Level: University Degree
  • Subject: Biological Sciences
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In Relation to human cells

In Relation to human cells: A. Outline the microscopic structure and function of the main types of cells found in human bone. (500 words) B. Describe the process of mitosis and outline how cell aging and cell death affects normal cell replication. (1000 words) A: The human bone which is a highly vascular tissue consists of three main types of cells these include; Osteoblasts, Osteocytes and Osteoclasts and there functions are remarkably important with regard to the formation of bones .Osteoblasts are bone forming cells. Osteoblasts are located in regions of high metabolism where they become synthesised and emit unminerialized substances. Osteocytes are produced from Osteoblasts, they are formed by creating bone tissue around themselves and therefore are known as mature bone cells. Their function involves in regulating the bone mineral content and regulating the amount of calcium going from the bone tissue out into the blood. Osteoclasts are large bone lining cells. They originate from Osteoblasts and are found on the surface of the majority of adult bones. Osteoclasts have many important functions which include the reabsorption or the collapse of the bone matrix and also to regulate the transfer of calcium and phosphate penetration to the bone. (Gunn p.3) These entire three cells merge together to create the process known as Ossification (Osteogensis) meaning bone

  • Word count: 1547
  • Level: University Degree
  • Subject: Biological Sciences
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Describe the Mechanism of Peptide Bond Hydrolysis by Serine Proteases and discuss the specificity of these enzymes

Describe the Mechanism of Peptide Bond Hydrolysis by Serine Proteases and discuss the specificity of these enzymes. Proteins are essential for all living systems and once used they need to be broken down into peptides and amino acids. These amino acids can then be recycled for the synthesis of more proteins. Berg et al (2002) stated that proteolytic reactions are also important in regulating the activity of certain enzymes. The hydrolysis of peptide bonds in the absence of a catalyst is extremely slow and a typical peptide bond in a neutral pH will have a hydrolysis half-life of between 10-1000 years (Berg, 2002). Berg (2002) explained that the resonance structure that accounts for the planarity of a peptide bond makes such bonds resistant to hydrolysis. This is because for every pair of amino acids linked by a peptide bond there are six atoms that lie in the same plane. Therefore it is essential to use a proteclytic enzyme or a protease to promote peptide bond cleavage. Serine proteases are used in the hydrolysis of peptide bonds and include chymotrypsin, elastase and trypsin. Proteases catalyse peptide bonds in polypeptides and proteins and according to Mathews et al (2000) serine proteases are distinct because they all have a serine residue that plays a critical role in the catalytic process. These serine proteases all have a similar three-dimensional

  • Word count: 675
  • Level: University Degree
  • Subject: Biological Sciences
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