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
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
Should Gene therapy be allowed to prevent cystic fibrosis?
Should Gene therapy be allowed to prevent cystic fibrosis? "Every week on average five babies are born every week with cystic fibrosis, and 3 sufferers die from it, usually caused by the damage to the lungs"1. CF is a life threatening disease that cannot be cured with the current treatments. The treatments include exercise, dietary programs, inhalation of antibiotics; breathing control techniques and daily physiotherapy. The initial cause of cystic fibrosis has been agreed by many sources such as www.cftrust.org.uk to be the single faulty gene that controls the movement of salt in the body resulting in the growth of internal organ's becoming clogged with thick sticky mucus. Problem: Although the methods mentioned above increase life span, they only target specific symptoms, rather than curing the defect itself, on the other hand, gene therapy is undergoing research, in both clinical and laboratory to see if it is safe and effective. "Only 33% of clinical trials have been focussed on 'single gene' diseases, and one of them is the common cystic fibrosis."15 The other 67% is clinical trials of gene therapy in humans have been cancer treatments. So treating gene therapy with cystic fibrosis is something which will have to be taken into consideration, but the technique gene therapy is always going under thorough research. Here are few reasons why gene therapy will not be
Can Germ line Gene Therapy be used as a treatment for Huntingtons Disease?
Can Germ line Gene Therapy be used as a treatment for Huntington's Disease? Target Audience: Biology A-Level Graduates Report Outline Gene Therapy has been used to reduce the effects of many diseases, but so far, very few solutions have arisen for Huntington's disease. I will be exploring the effectiveness of germ line therapy compared to its risks and morality. Problem Huntington's disease is a genetic condition where there is a mutation in the DNA sequence on the dominant gene 'huntingtin'. The mutation is repetitive so there is more than just one chromosome effected by this mutation. This means the offspring of a Huntington's disease carrier has a 50% chance of developing the disease. Huntington's disease is a neurodegenerative genetic disorder which means the neurones in the brain can lead to a cognitive decline over time. Because this process takes years before it shows any signs of effect, most people don't realize they have Huntington's disease until they reach mid-life. The gene 'huntingtin' codes for the Huntington protein, commonly found around areas of the brain. When a mutation occurs, this protein is no longer produced and instead a different form of protein is produced. This protein initially causes very little harm to the brain, but after a prolonged time, it damages nerve cells in the brain and leads to Huntington's disease. The full process of
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
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
Daphnia Write-Up
Daphnia Write Up In this experiment we investigated the effects of caffeine on the heart rate of living organisms. We chose to use daphnia in this experiment, a kind of small organism found in water, similar to a prawn or insect, which has completely transparent skin, making it easy to see the heart, and thus count the rate of its heart beat. My prediction was that the caffeine would increase the heat rate of the daphnia. Procedure The procedure was not too complicated, but there was a lot to keep in mind, and to be careful about. Since we were working with living organisms, we had to be extremely careful with there lives, and take care not to harm and stress them. . We set up a microscope, and got a ball of cotton wool ready. 2. We set up the different concentrations of caffeine. 0%, 0.125%, 0.25% and 0.5%. We couldn't use tap water, only distilled water, as tap water contains chlorine which can harm the daphnia. So 0% contained no caffeine, only distilled water. 3. We took two glass slides, and put a drop of chilled water in between them: this was so that the heat of the microscopes bulb did not harm the daphnia. 4. We captured a daphnia from the main tank which contained many; we tried to select the largest one possible. We caught it using a pipette, carefully drawing it into the pipette without harming it. 5. After we had caught it, we put it into the first
Mitosis and Meiosis, the defining differences.
Mitosis and Meiosis, the defining differences. The cell theory was first proposed by Schleiden in 1838 and Schwann in 1839. This theory was then extended upon by Rudolf Virchow in 1855 declaring that new cells only came from pre-existing cells. Shortly after, in 1887, Weismann suggested a specialist form of division occurred in the manufacture of gametes. These two forms of division are called Mitosis and Meiosis respectively. By definition, Mitosis and Meiosis are very similar, both being methods of cell division. However, the way in which the daughter cell is produced in these processes vary. The biological differences in these two processes lie between Mitosis and Meiosis I, as Meiosis II is almost identical to Mitosis. Mitosis As a consequence of Mitosis, a parent nuclei divides into two daughter nuclei, each with the same number of chromosomes as the parent nucleus. The division of the whole cell follows this. In order to accomplish this chromosome firstly replicate themselves during interphase. The two replicate chromosomes are known as chromatids and separate during mitosis. Cell division is a continuous process with no sharp distinction between the phases. There are 3 main stages: Interphase: this is the episode of synthesis and growth. The cell produces many materials essential for its own growth and for carrying out all its functions. DNA replication occurs
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
