Explain how twin and adoption studies attempt to distinguish genetic and environmental factors underlying the onset of schizophrenia within families. Review the studies and discuss two limitations of this.
Psychology Essay Explain how twin and adoption studies attempt to distinguish genetic and environmental factors underlying the onset of schizophrenia within families. Review the studies and discuss two limitations of this. Schizophrenia is the label applied to a group of disorders characterised by severe personality disorganisation, distortion of reality, and an inability to function in daily life. Symptoms are mainly disturbances of thought processes, but also extend to disturbances of emotion and behaviour. There are two symptom categories - acute schizophrenia characterised by positive symptoms, such as hallucinations and delusions; and chronic schizophrenia, characterised by negative symptoms such as apathy and withdrawal. However, DSM-IV has now moved away from these definitions and classified schizophrenia into three main sub-types: paranoid, disorganised and catatonic. Understanding Schizophrenia More research has, probably, been devoted to trying to understand the nature of schizophrenia than any other mental disorder. Somatogenic approaches have focused on the role of genetic mechanisms influencing the propensity to develop schizophrenia, while psychogenic approaches emphasise the effect of adverse childhood experiences, particularly abnormalities in family interaction in the aetiology of the disorder. Twin studies Twin studies offer a
Revision notes - origins of life on Earth, chemistry of life
8.4 LIFE ON EARTH 8.4.1 Origin of life 8.4.1.1 Identify the r/ship between the conditions on early Earth and the origin of organic molecules * Early earth contained no ozone layer › large amounts of UV radiation reached the earth * Little free oxygen (anoxic) therefore no ozone layer. * The volcanic emissions filled the atmosphere with methane (CH4), ammonia (NH3), H, CO2, CO and small amounts of water vapour. * The violent electrical storms and acidic rain formed the present warm and mineral-rich oceans. * There are only two possible ways organic molecules could have formed either - formed on earth from simpler molecules (Abiogenesis) - arrived from the cosmos (Panspermia) 8.4.1.2 Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on Earth Panspermia * Elements found in space (H, He, C, O, N, P) can combine to form organic molecules. * Some of these compounds including amino acids have been found in meteors that have struck the earth's surface. * Panspermia proposes that living organisms were seeded on earth as passengers on comets and meteors (ie. Life evolved elsewhere and travelled to earth) 8.4.1.3 Describe two scientific theories relating to the evolution of the chemicals of life and discuss their significance in understanding the origin of life Chemosynthesis * Formation of complex organic molecules on
Discuss the Impact of Genome Sequences on the Study of Development
Cells and Development Discuss the Impact of Genome Sequences on the Study of Development Development refers to the biological process an organism undergoes during growth. The introduction of genetics this century has greatly accelerated our understanding in this field. It appears to be exponential, continually more scientists are being drawn into the field and more data is being generated. In this essay I will briefly outline the course of development as a subject over the past 100 years (with a slight bias towards animal development) commenting on how important the use of model organisms has become and the contribution to the field their genomes have made. Development started with Aristotle in the 4th century BC. He noted the different ways in which animals were born, oviparity, viviparity etc, and began to look at the transition from conception to adulthood. Not much happened in the study for about 2000 years, until a man named William Harves in 1651 made the profound statement that all animals are from eggs, "ex ovo omnia". The subject never really took off because the specimens were too small to analyse. The invention of the microscope revolutionised the science and allowed study of these once unseen structures. This coupled with the Morgan's' use of Mendel's' genetic theory to create the chromosomal theory of inheritance allowed scientists to begin to make
An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and the Relative Duration of Each Phase of this Cellular Cycle
An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and the Relative Duration of Each Phase of this Cellular Cycle. Aim To conduct an investigation into the relative durations of the phases that occur in the mitotic nuclear division of meristematic Allium Sativum root tip cells, evaluating the validity of a hypothesis proposed that states that these mitotic phase durations will be of different. Hypothesis The Expected Results: The Relative Length of Each Stage of Mitotic Nuclear Division Through the process of conducting background research, it has been possible to suggest a theoretical ratio concerning the timing for each stage of the mitotic cycle; "Although the stages of mitosis are necessarily shown as static events, it must be emphasized that the process is a continuous one and the names "anaphase", "metaphase", etc., do not imply that the process of mitosis comes to a halt at this juncture. Moreover, the stages shown are not selected at regular intervals of time, e.g. in the embryonic cells of a particular grasshopper the timing at 38°C is as follows: prophase 100 min, metaphase 15 min, anaphase 10 min, telophase 60 min." 1 These specified times essentially form the ratio that will be used throughout the investigation (dividing each stage in the ratio by a factor of 5 provides the ratio (20:3:2:12), and allow a range of
An Investigation into the effect of caffeine on reaction times
An investigation into the effect of caffeine on reaction times and short term memory Aim To investigate the effect of varying doses of caffeine on performance in simple reaction time and short term memory tests. Research and Rationale Having carried out the core practical on the effect of caffeine on the heart rate of Daphnia, I wanted to investigate the effect of caffeine on other functions of the body, and how this effect comes about. Caffeine is a natural pesticide, found in the leaves, beans and fruit of over 60 plants1, however in humans it acts as a central nervous system stimulant, reducing fatigue and restoring alertness2. It is said to be the most widely used drug in the world, with an average intake of 241mg per person, per day according to a Bristol survey3. I therefore decided to explore how it could affect reaction times and the extent of short term memory, as these are two factors involved in alertness. It has a similar structure to adenosine, meaning it binds to adenosine receptors in the brain. Caffeine and adenosine - http://en.wikipedia.org/wiki/Image:Caffeine_and_adenosine.svg - 22.10.08 When a nerve impulse travels through the synaptic knob, opening the Ca2+ channels, it triggers the release of adenosine, which is synthesised and stored inside the synaptic knob. Normally, the adenosine acts as a neurotransmitter when it is released into the
The Human Genome Project
Amira Nicola January, 2001 The Human Genome Project The Human Genome project is a scientific research effort to analyse the DNA of human beings and that of several other types of organism. The project began in the United States in 1990 under the sponsorship of the U.S. Department of Energy and the National Institutes of Health. It was scheduled to be completed in 15 years. The project's goal is to identify the location of every human gene and to determine each gene's precise chemical structure in order to understand its function in health and disease. In the nucleus of every cell in the human body, there are 23 pairs of chromosomes, each of which is composed of several genes. Genes are discrete stretches of nucleotides that carry the information the cell uses to make proteins. The most important component of a chromosome is the single continuous molecule of DNA. This double-stranded molecule, which is shaped as a double helix, is composed of linked chemical compounds known as nucleotides. Each nucleotide consists of three parts: a sugar known as deoxyribose, a phosphate compound, and any one of four bases-adenine, thymine, guanine, or cytosine. These parts are linked together so that the sugar and the phosphate form the two parallel sides of the DNA ladder. This double-helical structure of the DNA molecule was discovered Watson and Crick in 1953, for
Too Much Information: Genetic Testing
Too Much Information: Genetic Testing Biology OAC ISP Essay - By Daniel Perez Genetic testing offers a whole new world of information about us and how our bodies work. The data we get from delving into our own genetic code can help us to cure or even prevent disease, stop medical conditions such as cancer or cystic fibrosis from even manifesting, or even correct these sorts of errors before birth, and many other beneficial uses. However, at this point in time, all of this is beyond us. We have no miracle cures, no 'magic bullet' with which to fight disease or genetic conditions, in fact, our understanding of the genetic code is so limited that it's as if we cannot see the forest for the trees. We have taken our first baby steps into understanding human genetics with the completion of the Human Genome Project, and now that we have the big picture, we can begin to interpret it. Through information gleaned from our DNA, we now know that there are certain medical conditions that are caused by certain patterns within the genes. Some examples of these genetic conditions include Tay-Sach's disease, Bloom syndrome, Deafness, cystic fibrosis, and many other diseases (http://www.einstein.edu/e3front.dll?durki=7158). Although many of these conditions are fatal, the ones that are not can be treated early, even before symptoms develop when possible, or if not treated, at least monitored
Cystic Fibrosis
Cystic Fibrosis Cystic Fibrosis (CF) is an inherited disease caused by a mutation in a gene responsible for producing a protein called "cystic fibrosis transmembrane regulator" (CFTR). Most people have 2 genes which produce this protein, but only one is needed to prevent the disease. This means that CF is "autosomal recessive", meaning that a person with the disease has a mutation in both CFTR (one mutated gene from each parent). Someone with one mutated gene and one normal gene is a carrier. Carriers do not show the symptoms of CF, as they have one working gene, but they may pass a copy of the defective gene onto their children. The CFTR gene is responsible for producing the CFTR protein, which allows Cl- ions to diffuse out of cells in water regulation. If the gene in the DNA is mutated, the mRNA produced in transcription will code for the wrong sequence of amino acids, so the protein made by the mRNA in translation will be the wrong shape, and therefore will not function correctly. This diagram shows the normal situation, where there is too much water in the mucus (outside the apical end of the cell). The sodium pump moves Na+ ions out of the cell, into the tissue fluid outside the basal end of the cell. The Na+ channel allows sodium ions to diffuse into the cell to replace those lost, causing a more negative water potential in the cell, so water moves out of the mucus
Problem - Maintaining the habitat of the capybara and breeding them for meat.
Problem - Maintaining the habitat of the capybara and breeding them for meat. The capybara (shown left 10) is currently classified as a common species in the 2000 IUCN Red List of threatened species. However, I have found through research that the number of capybara in the wild is declining, "Mortality from hunting is responsible for local extinctions or scarcity in many localities".1 Also this is confirmed by the statistic, "Today barely 100,000 capybaras are left in Venezuela". 2 The classification of the capybara as 'common' also means that people are unaware of the affect hunting will, and is having on the population of capybara living in the wild. The conservation of the capybara is overlooked by most people as it is considered a pest, due to its tendency to raid crops when fresh grazing is not available. The capybara has a great variety of habitats from forest and brush land to swamps, brackish mangrove areas and open savannah. The habitat needs to have all the components of water, dry ground on which to rest, grass and natural shelter1. These habitats are being destroyed by human activities, such as pollution of freshwater and the drainage of wetlands for agricultural use of the fertile soil, causing damage to the environment where the capybara seeks refuge from predators. Water is being abstracted for human usage increasing the threat to freshwater habitats.
The cloning of Dolly.
Contents Subject Page No. Introduction 2 Definitions of Terms 3 - 4 Arguments for and against 5 - 10 What the law states on the subject 1 Case studies 2 - 14 Islamic Perspective on Cloning 5 - 17 Personal Evaluation 8 Bibliography 9 Introduction Cloning On the 23 February 1997, the world woke up to news of a new technological advance. This advance was embodied in a "little lamb" going by the name of Dolly. At first glance, one could be forgiven for wondering what was so special about this white-faced sheep. Dolly looked like hundreds of the other lambs that dot the hills and fields of Scotland; and indeed for six months this lamb had grazed quietly and unnoticed among them. Dolly appeared positively ordinary. However, Dolly, despite appearances, had a most unusual conception. She was not the end result of a fusion of sperm with egg, which had been cloned from a single cell taken from the breast tissue of an adult sheep. It was the idea that this technology could be applied to humans. The cloning of Dolly raises serious ethical questions, particularly with respect to the possible use of this technology to clone human embryos. Religious groups across the world wondered if this is a miracle was to which we can thank God for, or to ignore it as an ominous way of playing God ourselves. Ethical choices must also have to be made. The public response to
