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
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
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:
Relating the structure and function of cell organelles
Relate the structure and function of cell organelles Cells are like cities with intricate organelles 'living and working' in it. There are basically two kinds of cells, namely Prokaryotic and Eukaryotic. Both plant cells and animal cells are eukaryotic while prokaryotic cells are simplier organisms that possess non-membrane bounded organelles. In most cells they contains the following organelles which carry out unique functions and allow cells to work properly. To start off with, nucleus is a large roundish organelle enclosed by a double membrane with numerous openings, namely nuclear pores, for nuclear traffic. It contains chromosomes and one or more nucleoli. Nucleolus is a spherical site where ribosomes are formed. Chromosomes contain DNA which tends to be packed in form of chromatin. Only during interphrase (a stage before a cell divides in a cell division process), chromosomes will be unravelled for easier replication. Tiny, hollow cylinders of protein called centrioles form a network of spindle fibres in the nucleus during nuclear division to pull chromosomes apart. The inner membrane of nucleus will break down and allow chromosomes lying freely in cytoplasm. DNA contains the genetic information and control the synthesis of protein. Each cell contains millions of ribosomes. They are very tiny, non-membrane bounded organelles made of protein and RNA which consist of
structural differences between fibrous and globular proteins.
Question: Explain with examples, the structural differences between fibrous and globular proteins. A globular protein has a fixed specific sequence of amino acids that are non-repetitive while a fibrous protein has a repetitive regular sequence of amino acid. For example, haemoglobin, a globular protein is made up of 4 polypeptide chains to form a tetramer (?2?2), composed of two identical alpha-beta (??) dimers. Collagen, a fibrous protein, has a primary structure characterized by a repeating tripeptide sequence of Glycine - X - Y. (X is proline, Y is either hydroxyproline or hydroxylysine) A globular protein has a more compact structure owing to highly contorted pattern of folding, bending and twisting along polypeptide chain to give the protein a spherical 3D shape while a fibrous protein is usually formed with elongated polypeptide chains wrapped around to form multi-molecular paralleled filaments to strands. For example, haemoglobin is a tetramer made up of 4 polypeptide chains of 2? chains and 2? chains. These four subunits are packed to form an overall spherically shaped molecule. However, collagen, a fibrous protein, is formed with three polypeptide chains lie parallel and wind round one another, forming a tropocollagen. The tropocollagen molecules lie side by side and are linked to each other giving a collagen fibril. A globular protein has its length of
Can heart disease be prevented?
Can heart disease be prevented? Preventing heart disease. Something our doctors tell us about all the time, something we all want to do, but what exactly is a "heart disease". How can we prevent it if we don't even know what it is? Every one has heard the terms "heart attack" and "stroke" but hardly anyone knows what they mean. Let's start right at the beginning. A heart disease, medically known as cardiovascular disease, is a disease of the heart and the blood vessels. Most people think only the middle aged and elderly get such diseases but no, cardiovascular diseases can be found in children as young as the age of seven years old. This is strongly liked with the children's lack of exercise and a poor diet. There are many types of cardiovascular diseases of which the major ones are atherosclerosis, coronary, rheumatic, congenital, myocarditis, angina and arrhythmia. Heart disease can arise from congenital defects, infection, narrowing of the coronary arteries, high blood pressure, or disturbances. (1) Atherosclerosis is the thickening of the inner layer of the arterial walls due to the deposit of cholesterol, fibrous tissue, dead muscle cells and blood platelets. This deposit is also known as atheromatous plague or an atheroma. Rheumatic heart disease used to be one of the most serious heart diseases in both children and adolescence as it involves damage to the entire
Investigate the water potential of celeriac.
Aim Investigate the water potential of celeriac. Apparatus Celeriac - this is the specimen that we will be finding the water potential of. .00 mol dm-3 sucrose solution - this will be placed in the test tube in which the experiment will take place. We will dilute the solution to produce a range of concentrations. 0.0ml Graduated Pipettes (x2) - I had a choice of 5.0ml, 10.0ml and 20.0ml graduated pipettes. I chose this size pipette because it is time efficient and accurate at the same time. It is an accurate piece of equipment because as opposed to standard pipettes, this graduated pipette has 0.1ml graduations to ensure the utmost accuracy. One pipette will be used for water and one will be used for sucrose solution. 250ml Beakers (x2) - these will be used to hold water and the 1.00 mol dm-3 sucrose solution in a safe environment. Cork Borer - this will be used to cut the precise shape of the celeriac. This will also ensure that the surface area to volume ratio is constant throughout the experiment. Razor - this will be used to cut the pieces of celeriac to a precise length. Ruler - this will be used to measure the length of celeriac that will be used in the experiment. Scales - they will be used to measure the mass of celeriac before and after the experiment with accuracy. Therefore, the mass increase/decrease can be calculated after the experiment. These scales
