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
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
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
The arguments for and against developing a “genetic fingerprint” profile for all members of society
AS Module 4 Essay - The arguments for and against developing a "genetic fingerprint" profile for all members of society. Genetic fingerprinting is a rapidly developing technique involving the cutting of DNA and using it to distinguish between individuals of the same species. This is useful because every individual produces a unique genetic fingerprint as we all have different DNA sequences. Several steps are undertaken in order to prepare a genetic fingerprint. The non-coding DNA provides the basis of a genetic fingerprint (Potter, 2001). Firstly, a DNA sample is taken from, for example; the blood, a hair root or a mouth swab. If there is not enough DNA in the sample, a polymerase chain reaction (PCR) may be done to produce more. This is where the enzyme, DNA polymerase is used to amplify a piece of DNA by in vitro enymatic replication (http://en.wikipedia.org/wiki/Polymerase_chain_reaction, 02/03/2008). The next step would be to cut the DNA into pieces, and this is done by using the restriction endonuclease enzyme. The enzyme makes two incisions, one through each of the sugar-phosphate backbones (i.e., each strand) of the double helix without damaging the nitrogenous bases (http://en.wikipedia.org/wiki/Restriction_endonuclease, 02/03/2008). Now the DNA sections can be separated by the process of electrophoresis, which is a technique, used in the laboratories that result in
How Zoo's Avoid Inbreeding in a Limited Captive Population
HOW CAN A ZOO WITH A LIMITED CAPTIVE POPULATION AVOID INBREEDING? * Contents. * Introduction. * Implications of Inbreeding in Limited Captive Population. * Solutions on Avoiding Inbreeding. * Ethical Issues How can Zoos with limited Captive Population Avoid Inbreeding Introduction; Animal Inbreeding was a problem in the early 1900's. London Zoo was one of the first and largest zoo's open in the world, Zoo keepers and scientists were ignorant and animals were kept in iron cages and confined spaces. They were not aware of the problem that inbreeding caused to captive populations. By the 1990's studies in plants and animals indicated that 'inbreeding depression' and many other effects were taking place naturally and in captivity. One solution to this was made in 1988 European zoos formed European Community Association of Zoos and Aquaria (EAZA), the countries involved were to keep detailed reports on animals which would be shared with other Zoos to keep breeding in the best possible interest of the animals. Implications of Inbreeding with limited Captive Population; Inbreeding is the term used when breeding within the family, close and distant in plants and animals, however, there are consequences of inbreeding, and bares illness and health problems within a population if continued over generations. Over generations more frequently recessive and deleterious traits can
Evolution. This issue report will aim to address the Theory of Evolution by explaining key concepts and ideas in an informative and unbiased way. It will set forth to describe the theory, by highlighting its main components,
Evolution Candidate Number: **** [An insight into the controversial issue of evolution.] Deadline: 24th April '09 Edexcel GCE Biology Introduction This issue report will aim to address the Theory of Evolution by explaining key concepts and ideas in an informative and unbiased way. It will set forth to describe the theory, by highlighting its main components, and also touching upon significant moments in time that shaped the modern Theory. I will be identifying the problem/s biologists have in regard to this issue, and the measures they are taking to produce an effective solution. Problem The problem biologists are struggling to solve is the full establishment of the Theory of Evolution as an accepted fact throughout the global population. And that is why the scientific community is determined to enlighten everyone with their own understanding. On a near global scale, the Theory of Evolution has become a default ideology that defines the existence of life. It is defined as scientific and logical, and it has become extremely dominant due to the many biologists who agree with it because of its simplicity, in terms of understanding the basic concept. It is taught as a standard in educational facilities, and therefore cannot be disputed. The problem with this issue is that while calling it a 'Theory', the majority of proponents consider it as solid fact. They are convinced
