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
The effect of amylase concentration on the breakdown of starch
The effect of amylase concentration on the breakdown of starch This Essay was awarded a mark of A, so they say. Only the plan is included For this investigation I am going to investigate the effect of the concentration of an enzyme, in this case Amylase, on the time taken for the enzyme to fully breakdown the substrate, which in this case is starch. The reason why these two enzymes have to be used is because each enzyme is designed specifically to break down only one substrate as each enzyme is made of a protein that causes it to be a specific shape, in this case the enzyme Amylase can only break down starch to dextrin. I am going to do this by planning an experiment, carrying out the experiment, recording any relevant results and plotting graphs from which I will be able, hopefully to gain a strong conclusion. I will finally evaluate the whole investigation. Before the experiments start we will be given a bottle containing a 1% solution of starch and another bottle containing a 1% solution of the enzyme Amylase. From these bottles I will be able to take out as much of either solution as I wish. I cannot start he experiment until I know which factors I am going to change and which I am going to keep constant. Because the thing I am trying to test in the effect of the concentration of the enzyme, the only thing that I should be changing in each experiment is the
Investigating the breakdown of hydrogen peroxide using celery tissue to supply the enzyme catalyst
Investigating the breakdown of hydrogen peroxide using celery tissue to supply the enzyme catalyst Variables * Amount of celery * Concentration of celery, more or less watered down. * Concentration of Hydrogen Peroxide (H202) * The amount of H202 * The temperature of H202 I am going to vary the concentration of the hydrogen peroxide. I think that varying the concentration of the liquid will be the best experiment to do and will hopefully give a strong set of results, which will enable me to obtain clear conclusions. Prediction The rate of an enzyme- controlled reaction depends on the temperature, pH, and concentrations of the enzyme and its substrate. The more enzyme molecules produced by a cell, the faster the reaction will proceed. Similarly, an increase in the substrate concentration will speed up the reaction if there are enough enzymes molecules to cope with the additional substrate. Therefore by diluting the hydrogen peroxide with water, this will decrease the rate of decomposition of the H202, and the less gas will be given off. The enzyme in the experiment is catalase. Hydrogen peroxide is poisonous and the catalase works to render the hydrogen peroxide harmless by breaking it down to water and oxygen. If the concentration of H202 is less, then there is more water present, and there are less hydrogen peroxide molecules, so there is less for the catalase to
Investigate the effect of pH on Trypsin
Biology Coursework Plan Aim Investigate the effect of pH on Trypsin Prediction / hypothesis * pH will affect trypsin action * as pH increases, tryrpsin will show increasing activity up to an optimum pH * the action of the enzyme trypsin on the substrate egg albumen will be at a maximum at an optimum pH of around 7 (neutral) to 8 (slightly alkaline) see later about pH of duodenum * as pH continues above this, trypsin activity will decrease Background / Introduction Proteins are complex organic compounds consisting of amino acids joined by peptide bonds which form highly folded three dimensional or tertiary structures. The bonds that maintain the tertiary structure of the protein are a result of interactions between the R groups of the amino acids: disulphide bridges (strong covalent), hydrogen (weak) bonds, ionic or electrovalent bonds, hydrophobic interactions. Enzymes, such as trypsin, are globular proteins with a specific shaped active site into which the correct substrate can fit. trypsin protein / polypeptide peptides Trypsin is a protease enzyme: a hydrolytic or digestive protein that cleaves peptide bonds. It is produced in the pancreas in the form of trypsinogen, and is then transported to the duodenum of the small intestine, where the digestion of proteins to polypeptides and amino acids begins. The pH
AS Edexcel Biology - Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas).
The effect of caffeine on heart rate. Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas). Background Information: Plants produce caffeine as an insecticide. Cocoa in South America, coffee in Africa and tea in Asia has all been used as 'pick-me-up' drinks containing caffeine. These days caffeine is used in a wide variety of soft drinks such as cola to enhance flavours. In addition to this, stimulant drinks such as Red Bull and Boost also carry high levels of caffeine as well as some weight-losing drugs and medicines such as Aspirin. IN humans, caffeine acts as a stimulant drug, causing increased amounts of stimulatory neurotransmitters to be released. At high levels of consumption caffeine has been linked to restlessness, insomnia and anxiety, causing raised stress and blood pressure. This can lead to heart and circulation problems. Hypothesis: I think that the Daphnia's heart rate will rapidly increase when the caffeine solution is added. This is because increases the amount of neurotransmitters released in the body so everything in the body will be working at a faster rate because of these. Planning: -Risk Assessment: 1. I need to be aware of weils disease so I will not come in to direct contact with the pond water and regularly wash my hands thoroughly throughout the experiment. 2. I will need to constantly keep my glassware on
Compare and Contrast the Transport System of a Mammal and a Plant
Compare and Contrast the Transport System of a Mammal and a Plant Introduction: Both mammals and plants require a transport system to satisfy the requirements of rapid supply of nutrients & gases, as well as the removal of waste products. Due to their huge surface area, transportation of substance is not quick enough if rely solely on diffusion, therefore a transport system is needed. A transport system relies on the mass flow movement of fluids due to pressure difference. The Mammalian Transport System: Mammals are metabolically active and have high nutrients demand, therefore a cardiovascular system is used to satisfy the need. This consists of a four-chambered heart and a system of interconnecting tubes (i.e. blood vessels) where blood is moved through them to the rest of the body. Mammal has a closed double circulatory system, which consists of pulmonary circulation going to the lungs and systemic circulation going to the rest of the body. With two circuits, a higher pressure blood can be achieved going to the body to form tissue fluid and deliver respiratory gases more quickly. A slower blood flow is desired when going to the lungs to allow more time for gas exchange and prevent damage on lung tissues. Blood never leave the vessels during transport so that a quicker blood flow rate can be obtained and this also allows vasoconstriction or vasodilatation to occur. The
biology differences in animal and plant cells
Sarah Huckerby 30059987 Di Paul Biology Group 1 Contrasting the structure of plant and animal cells Modern cell theory states that all living matter is composed of cells and they arise from other cells. They contain hereditary information of the organisms of which they are a part; the cell is the basic unit of all living matter. Cell are made up of Protoplasm, which is a granular substance resembling the white of an egg, the cell membrane, inorganic salts, carbohydrates for energy, Lipids which are fats and nitrogenous substances, amino acids which are obtained from proteins (Moth.E 2003) Organisms mostly consist of Eukaryotic cells, which contain a true nucleus and also contain other organelles which are sub-cellular, permanent structures that carry out particular functions in the cell. Plant and animals are composed of cells that have many similarities. All plant and animal cells have a nucleus surrounded by Cytoplasm bound by a cell membrane, cytoplasm is the material inside the cell but outside the nucleus, it contains different structures and substances. It is the "brain" of the cell and is contained within the nuclear membrane (which insures that the interior of the nucleus is isolated from the cells cytoplasm allowing two different environments to be maintained,)it contains pairs of chromosomes each carrying hereditary DNA (Deoxyribonucleic acid) (Toole, G & S
Cellular Respiration and the Role of Mitochondria
Cellular Respiration and the Role of Mitochondria Cellular respiration is the process of oxidising food molecules, such as glucose, to carbon dioxide and water and releasing the covalent bond energy in the form of ATP for use by all the energy-consuming activities of the cell. Mitochondria are membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells. They are where cellular aerobic respiration occurs; indeed cells without mitochondria cannot respire aerobically. Cellular respiration consists of two broad phases, initially, glycolysis (the breakdown of glucose to pyruvic acid) Occurs, this is followed by the oxidation of pyruvic acid to carbon dioxide and water. In eukaryotes, glycolysis occurs in the cytosol (The fluid in which cell organelles are suspended). The remaining processes take place in the mitochondria. The first stage, glycolysis is the anaerobic catabolism of glucose, it occurs in almost all cells. The process uses glucose and co-enzyme NAD (Nicotinamide Adenine Dinucleotide), and yields 2 molecules of Pyruvic acid, as below C6H12O6 + 2NAD+ -> 2C3H4O3 + 2NADH + 2H+ The free energy stored in 2 molecules of pyruvic acid is somewhat less than that in the original glucose molecule. Some of this difference is captured in 2 molecules of ATP. The Krebs Cycle then decarboxylates the pyruvic acid resulting in a 2-carbon fragment of
The structure and function of the ileum in relation to absorption and digestion.
SUMUDU LANKATILAKE 7-FEB-03 THE STRUCTURE AND FUNCTION OF THE ILEUM IN RELATION TO ABSORPTION AND DIGESTION The ileum is the second part of the small intestine located after the duodenum. It has a vital function in digestion and has a suitable structure to accommodate for its functions. The ileum is 6 meters long and the main site foe the absorption of the soluble products of digestion. The ileum is efficient at this for the following reasons: * It is fairly long and presents a large absorbing suface to the digested food. * Its internal surface is greatly increased by circular folds bearing thousands of projections called villi. These villi are about 0.56mm long and may be finger like or flattened in shape. * The lining epithelium is very thin and the fluids can pass rapidly through it. The outer membrane of each epithelial cell has microvilli which increase the exposed surface of the cell by 20 times. * There is a dense network of blood capillaries in each villus for quick absorption and maintainance of the concentration of the concentration gradient. * The villi possess smooth muscle fibres that contract and relax and mix the food up and bring it into contact with the epithelial cells of the absorptive surface. * Each villus has a lacteal for the absorption of fatty acids and glycerol, most of which combine to form fats. The ileum is made up of 4 layers:
