Discuss The Significance Of Normal And Abnormal Mitosis And Meiosis In The Lifecycle Of Humans
Discuss The Significance Of Normal And Abnormal Mitosis And Meiosis In The Lifecycle Of Humans. Introduction: Mitosis is a type of cell division. The nucleus divides once and produces two identical nuclei. The new daughter cells are genetically identical both to each other and the parent cells. The only source of genetic variation in the cells is via mutations. Mitosis is used for growth and repair. Some tissues must be repaired often for example, the lining of the gut, white blood cells, skin. The skin cell lifespan is only a few days. The same chromosome number is retained from generation to generation. The duplication of a chromosome is followed by a nuclear and cell division. Nuclear division its self is a continuous process, but for ease of description, four main stages are recognised. The four stages are known as Prophase, Metaphase, Anaphase and Telophase. When a cell is preparing to divide, it is said to be in Interphase. At this stage the cell forms new cell organelles to supply the daughter cells. The DNA replicates so the there is sufficient DNA for the two daughter cells. The cell then builds up its store of energy in preparation for the cell division. Mitosis starts with Prophase, where the chromosomes condense becoming more tightly coiled and folded and so appear more shorter and fatter as Prophase progresses. As soon as the chromosomes begin to condense,
proteins in mammalian PC12
The behaviour of long polyglutamine-containing proteins in mammalian PC12 cells Project report in partial fulfilment for the degree of MSc in Neuroscience August 2008 Janahi Visakan Supervised by Dr Angela Hodges Department Of Neuroscience Institute of Psychiatry King's College London University Of London The behaviour of long polyglutamine-containing proteins in mammalian PC12 cells Abstract Huntington's disease is an autosomal dominant, inherited neurodegenerative disorder induced by a glutamine expansion repeat at the N-terminal end of the huintingtin protein. These N-terminal fragments of huntingtin aggregate in the nucleus and destroy cells. This genetic disorder is accompanied by motor, cognitive, personality changes and psychiatric symptoms. If the number of glutamine residues increase to more than 37, then this induces an adult, onset gradual progressive neurodegeneration known as HD.The genome of D.discoideum, a social amoeba consists of polyglutamine fragments longer than 40 residues. These long polyglutamine fragments do not confer any toxic effects .In addition the genome sequencing of D.discoideum has demonstrated that this organism is able to withstand a large number of proteins containing long polyglutamine stretches. A synthetically generated CAAX repeat construct was clone d into a mammalian expression vector using the gateway system (Invitrogen) to
Mitochondrial genetics. Are there really only maternally inherited mitochondria in our cells? What happens if paternal mitochondria happen to be present in the autosomal/germ cells? Is maternal mtDNA inheritance a universal mechanism that works for the en
Hypothesis. Mothers pass on mitochondrial DNA (mtDNA) to their offspring. Paternal mtDNA is considered to cause abnormalities in the most mammalian and human organisms. Research Question. Is it true? Are there really only maternally inherited mitochondria in our cells? What happens if paternal mitochondria happen to be present in the autosomal/germ cells? Is maternal mtDNA inheritance a universal mechanism that works for the entire living creatures and what are the benefits? Mitochondrion is an organelle with a specific subset of its own DNA (mtDNA), which different from chromosomal DNA in most organisms. Its DNA is a plasmid, - an unwrapped circular bacterial DNA molecule. According to the recent hypotheses, a mitochondrion as a bacterium had potentially merged with the single eukaryotic cell to form symbiotic relationships. These 'infected' cells had further formed organisms - ancestors of present species. Organisms had inherited mitochondria through thousands of years. One of the most interesting observations made by recent studies is the pattern of mtDNA inheritance in humans and most eukaryotic multicellular organisms excluding hybrids (interspecific crosses) and plants (Foley, 2003; Hayashida, 2005). In humans it is strictly a mother who passes mtDNA on to the offspring, while hybrids receive and express both maternal and paternal inheritance in different
The Endocrine systems involvement in the control of the female reproductive system.
THE ENDOCRINE SYSTEMS INVOLVEMENT IN THE CONTROL OF THE FEMALE REPRODUCTION SYSTEM The Endocrine system comprises of the pineal body, thymus, thyroid, parathyroids, adrenals, pancreas, ovaries and testes; they are all under the control of the pituitary gland. The Endocrine system discharges hormones that control the actions of body tissues. Hormones are made of amino acids or steroids which are released from endocrine cells at specific times and in measured quantities to have an effect on intended organs; the transformations created by the release of these hormones are normally slow or long-term changes. Hormones are released straight into the blood stream or body cavities and each hormone acts on certain target zones from the source. The pituitary gland The pituitary gland is liable for synchronizing the activities of the system, and is separated into two lobes, an anterior lobe and a posterior lobe. The anterior lobe is responsible for the production of subsequent growth hormones: probating, follicle stimulating, luteinizing, thyroid stimulating, adrenocorticotrophic and melanocyte stimulating. Growth hormones stimulate the growth of long bones, which is primarily important throughout childhood and adolescence. Prolactin stimulates the mammary glands of the breast, to promote and sustain milk production. Follicle-stimulating hormone (FSH) encourages the production
Nutrition is the relationship of foods to the health of the human body.
Nutrition is the relationship of foods to the health of the human body. Proper nutrition means receiving enough foods and supplements for the body to function at optimal capacity. It is important to remember that no single nutrient or activity can maintain optimal health and well being, although it has been proven that some nutrients are more important than others. All of the nutrients are necessary in different amounts along with exercise to maintain proper health. There are six main types of nutrients used to maintain body health. They are: carbohydrates, fats, proteins, vitamins, minerals, and water. They all must be in balance for the body to function properly. There are also five major food groups. The groups are: fats and oils, fruits and vegetables, dairy products, grains, and meats. A healthy diet and nutrition are important factors that help to keep our body in good health through our entire life. Food is very important to our life. Food provides nutrition for the human body's health. To stay healthy we should understand the inseparable relationship between diet and nutrition. When first starting this assignment I didn't think that I was going to learn anything new that I didn't already know about my eating habits. After writing down a days worth of food and drink and then analysing all the information and actually calculating out everything, I
The Female Orgasm: Adaptation, Artefact or culturally learned? ( Department of Psychology - University of Liverpool)
The Human Female Orgasm: Adaptation, Artefact, or culturally learned? Rajat Passy Department of Psychology University of Liverpool Liverpool United Kingdom The Human Female Orgasm: Adaptation, Artefact, or culturally learned? Word Count: 2958 (excluding in-text and end-text referencing and quotations) The female orgasm has been a source of fascination for a variety of groups from sex researchers to the lay public, and evolutionary psychologists are no exception. Evolutionists have not had much difficulty explaining the male orgasm, due to its direct relationship with reproduction. But the Darwinian rationale behind the female orgasm has remained elusive. Women are able to have sexual intercourse and even conceive a child - doing their part for the perpetuation of the species - without experiencing orgasm (Smith NY times, 2005). Unlike the unicorn, (which is specially interesting precisely because it does not exist) or extrasensory perception (which probably does not exist but is interesting because of the possibility that it might) or the above mentioned male orgasm (which exists with monotonous regularity and for the most part is interesting only to people directly involved in one) the female orgasm definitely exists and yet arouses interest, debate, ideology, technical manuals and popular literature simply because it is so often absent (Symons, 1979). There have
The polymerase chain reaction (PCR) is an in vitro technique, which allows the amplification of a specific deoxyribonucleic acid (DNA) region that lies between two regions of known DNA sequenc
THE POLYMERASE CHAIN REACTION The polymerase chain reaction (PCR) is an in vitro technique, which allows the amplification of a specific deoxyribonucleic acid (DNA) region that lies between two regions of known DNA sequence1,2. It is the most widely used target amplification technique that is found in molecular biology. This technique, which was first described by Saiki et al3 and Mullis et al4, has made it possible to detect and quantitate rare target nucleic acid sequences isolated from cell, tissue or blood samples5. The basis of this technique is the ability of DNA polymerase to extend an oligodeoxyribonucleotide primer that is specifically hybridized to a single-stranded DNA template5. Such amplification of DNA is achieved by using oligonucleotide primers or amplimers1. These are short, single-stranded DNA molecules which are complementary to the ends of a defined sequence of DNA template1. A DNA polymerase will enable the primers to extend on single-stranded denatured DNA (template), in the presence of deoxynucleoside triphosphates (dNTPs) under suitable conditions1. New DNA strands are synthesized and bound complementary to the template strands as double-stranded DNA molecules1. Basically, PCR consists of three thermally separated steps: denaturation at 95°C to ensure complete separation of DNA duplexes into single-stranded molecules; annealing at a temperature
The role of hormones in the female reproductive system.
The role of hormones in the female reproductive system The oestrus cycle is the continuing process of fertility and non-fertility controlled by several hormones and the endocrine system. This consists of the hypothalamus, the anterior pituitary gland, the ovaries and the uterus, known as the hypothalamic-pituitary-ovarian-uterine axis. Oestrus normally lasts for 18 to 24 days but this figure can vary in specific circumstances such as early puberty when the cycle lasts for a lot less time (3 to 12 days) and also when the cycle commences after pregnancy and parturition (Fuquay 2002). The oestrus cycle halts during pregnancy due to the large amounts of progesterone in the blood supplied by the Corpus Luteium (CL). Progesterone is vital for maintaining pregnancy and also for stimulating the growth of mammary alveoli for the purpose of lactation. Gonadotrophin releasing hormone (GnRH) begins a cascade of hormones through the animal that are responsible for the oestrus cycle taking place. It is secreted in a pulsating manner with rises and falls in concentrations from the hypothalamus where it is transported to the anterior pituitary gland. It is here that the GnRH controls the release of two protein hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) which are known collectively as gonadotrophins. Because the release of GnRH is in waves, consequently FSH
Control of Respiration
Introduction The process of gas exchange within the body is know as respiration and has three fundamental stages: * Pulmonary ventilation - also known as breathing, is the inhalation and exhalation of gas between the air outside and the alveoli of the lungs * External respiration - refers to the exchange of gases in the alveoli of the lungs and the blood in pulmonary capillaries, where the capillary blood gains O² and loses CO² * Internal respiration - is the gas exchange between blood in systemic capillaries and tissue cells. This process can also be referred to as cellular respiration. Pulmonary ventilation is a result of alternating pressure differences, between the atmosphere and the alveoli of the lungs, due to contraction and relaxation of respiratory muscles. To enable air to flow into the lungs, the pressure within the alveoli must be lower than that of the atmosphere outside. This can be achieved by increasing the volume of the lungs. The process of pulmonary ventilation is organized by the CNS via the spinal nerves. These spinal nerves innervate the intercostals muscles and the diaphragm by fibers of the phrenic nerves which appear from the spinal cord at cervical levels C3, C4 & C5. The output of these fibers, also known as motor neurons, is controlled by the medullary ryhthmicity area located at the respiratory center in the medulla oblongata in the
Sameness of Twins
The Sameness of Twins: A Critique of Literature The root word of twinning is twine, suggesting a double thread. This is acknowledged as global human trait and is intrinsically part of what is inherited. The incidence of twinning differs, ranging from 1 out of 30 births among Nigerians, to as rare as 1 in 150 births among Japanese. The distinction between monozygous and dizygous twins lies in the fact that monozygous twins arise from the same ovum, while dizygous twins hail from separate ova (Medawar & Medawar, 1983; Thompson & Thompson, 1980). Figure 1. Formation of identical and fraternal twins. Source: http://www.pennhealth.com/health_info/pregnancy/graphics/images/en/19745.jpg It has been widely acknowledged in biological sciences (Medawar & Medawar, 1983), genetics (King, 1968), and immunology (Humphrey & White, 1970) that monozygous twins are "genetically identical". However, the current paper now comes to question where this identicality ceases. Their differences are attested to by the physical and pathologic distinctions found across empirical studies (Milne, 1976; Osborne & De George, 1959; Schimke, 1978; Stern,1973). Schimke (1978) asserts that these distinctions come from "environmental differences, cytoplasmic differences, equations of heritability versus variability, non-penetrance of the heritable mutant gene, gonadal mutation, and premutation."