A Level Biology revision notes
Balanced Diet * Energy Balance o Energy is obtained from food * Main energy from carbohydrates (glucose) and fats * Proteins are used for growth and repair first * Excess proteins is converted to energy o Out of balance * More energy/food than required › obesity * Less energy/food than required › starvation o Types of carbohydrates * Intrinsic sugars: found within cells (fruits) * Extrinsic sugars: sugars that have been added to food (processed food) * Milk sugars: found in milk products * Basal Metabolic Rate (BMR) o Energy needed at rest (not when asleep!) for routine tasks of cells (excrete waste) o Factors that influence BMR * Age * Young > Old * Growth requires more energy › children, pregnant women (fetus) * Young and active people have more muscles than older people * Sex * Male > Female * Women have more adipose than muscle tissue * Muscles (work out) require more energy than fat cells (storage) * Body size * Tall and thin > short and obese * Tall and thin people have a large surface area but small volume * Loose heat quicker * Need more energy to maintain body temp * High body mass > Low body mass * High body mass › more cells that require energy * Starvation o No carbohydrates and fats are available in the diet o Body starts to break down its own proteins (muscles) Function of Fibres * Polysaccharides (cellulose) that
An investigation to find out how temperature affects membrane permeability.
An investigation to find out how temperature affects membrane permeability. This Problem What we will hopefully try and find out in this investigation is if temperature affects the permeability of a beetroot membrane Hypothesis As the temperature in which the beetroot is put in increases there will be more red dye diffusing out of the beetroot due to the denaturing of the proteins in the cell membrane as a result of the high temperatures. Background Knowledge The cell membrane can be represented as the fluid mosaic model as shown below. It is selectively permeable and controls what enters and exits the cell. It does this by proteins, however small lipid molecules, non-polar molecules and small water molecules can enter and exit the cell straight across the membrane through the phospholipids, due to the properties of the molecules enabling them to do so. Extrinsic and intrinsic proteins in the cell membrane help other the molecules enter or leave the cell by either facilitated diffusion or active diffusion. Different proteins are specific to certain molecules hence the cell membrane being selectively permeable. Here is a diagram of the cell membrane: As you can see the cell membrane is made up of a phospholipid bilayer which the extrinsic and intrinsic proteins span through. Some of the extrinsic proteins act as antigens for cell recognition with a carbohydrate
An investigation in to how enzyme ripeness in pineapple affects the setting of gelatine.
An investigation in to how enzyme ripeness in pineapple affects the setting of gelatine Gelatine, more commonly known as Jelly, is a substance that consists mainly of collagen, a protein found in animal tendons and skin. The gelatine used for cooking purposes is usually in the form of granules. These granules swell when they are re-hydrated in water, but only fully dissolve in hot water. As this solution cools it sets to a moisture holding gel. This gel forms due to the proteins in gelatine joining to form a web like structure. In Module 1 A-level Biology, we learn about the structure of a protein molecule. A protein molecule is formed when amino acids join together by condensation, forming a peptide bond and water as a bi-product. A chain of many amino acids is known as a polypeptide and a protein can consist of one or more of these. The opposite of condensation is hydrolysis. When hydrolysis occurs a peptide bond is broken and water is used up in the reaction. There are specific enzymes called proteases (Module 2), which can be found in fruits such as pineapple, that speed up the hydrolysis reaction that breaks down protein molecules. From research I have found that it is a protease called bromelain found in pineapple, which in the scenario is preventing the gelatine from setting by breaking up the proteins forming the web like structure. It is also in
Amylase Investigation
GCSE Biology Coursework-Plan "The enzyme salivary amylase, formerly known as ptyalin, initiates the break down of starch. This is the only chemical digestion that occurs in the mouth. The function of salivary amylase is to break the chemical bonds between some of the monosacchaides in the starches to reduce the long-chain polysaccharides to the disaccharide maltose." This quote is from Principles of Anatomy and Physiology. The equipment I will be using is as follows- One Beaker Two Syringes One Pipette Two Test Tubes One Boiling Tube One Spotting Tile One Kettle One Stop Watch One Thermometer I am going to test how quickly amylase breaks down starch at different temperatures. I am going to do this by extracting 10cm3 of starch and 10cm3 of Amylase using a syringe into two separate test tubes. I will then place the two test tubes in a beaker containing water at certain temperatures for five minutes. The temperatures will be 0, 10, 20, 40, 60, 80 and 100 degrees centigrade. To get to the higher temperatures I will use a kettle. I am leaving the test tubes in a beaker for five minutes to allow the starch and amylase to equal that of the water temperature. After five minutes I will mix the starch and amylase together into a boiling tube, and start the stop clock. After every 30 seconds I will extract a drop of the starch/amylase mixture using a pipette into a
An Experiment to find out the Effect of Temperature on the Enzyme Catalase.
An Experiment to find out the Effect of Temperature on the Enzyme Catalase Plan I plan to investigate the effect of temperature on enzyme activity. If I was to carry out this experiment, I would need to carry out an experiment to work out the optimum temperature or range of temperatures at which the enzyme works best. At higher biological temperatures I believe that the enzyme and the substrate would have increased molecular motion and collide more often, hence reaction rate will be higher. However I know that if I use too high a temperature the secondary and tertiary structures are disrupted and the enzyme is said to be denatured. I know that catalase is found in the liver, as it breaks down Hydrogen Peroxide, and most mammalian enzymes work at biological temperatures which range from 37°C - 40°C. This is what I predict my optimum range to be. Variable How Will it be controlled? Why will it be controlled? Catalase I will measure out carefully 0.3cm3 using a 1cm3 micro pipette It will keep the same volume of enzyme in solution in order for the results to be accurate and valid, because if there is more catalase the reaction will occur faster as more enzyme substrate complexes will be formed. Hydrogen Peroxide I will measure out carefully 5cm3 using a 5cm3 graduated pipette It will keep the same volume of the substrate in solution in order for the results to be
An experiment to test the effect of different temperatures on the permeability of cell membrane.
An experiment to test the effect of different temperatures on the permeability of cell membrane. Aim In this experiment, I am trying to find out how, why, and by how much does the difference in temperature affects the permeability of cell membrane of plant cells. Prediction Having done a pilot experiment and by using the scientific knowledge gathered, some predictions can be made. The permeability of cell membrane should increase as the temperature increases, and this is shown by the decrease in the percentage transmission of light on the colorimeter. As guidance, the results of the pilot experiment could be used: Readings taken from the pilot experiment Time taken(min) Temperature(°C) % Transmission of light Volume of water(ml) 20 20 96 5 20 30 81 5 20 45 70 5 20 60 48 5 Graph to show the relationship of temperature and the % transmission of light. Results similar to the pilot experiment are expected, and so at 20°C, the cell membrane is not very permeable, shown by the high % transmission of light, expected to be about 90-100%. The membrane would start getting more permeable at around 30-40°C, shown by the decreased % transmission of light, expected to be about 85-65%. The cell membrane would get much more permeable when temperature rises above 45°C, shown by the low % transmission of light, expected to be below 50% at around 60°C. We can
Aids and HIV.
Aids and HIV AIDS (acquired immune deficiency syndrome) is a condition caused by a virus called HIV. This virus attacks the immune system, the body's "security force" that fights off infections. When the immune system breaks down, you lose this protection and can develop many serious, often deadly infections and cancers. These are called "opportunistic infections" (OIs) because they take advantage of the body's weakened defences. You have heard it said that someone "died of AIDS." This is not entirely accurate, since it is the opportunistic infections that cause death. AIDS is the condition that lets them take hold. HIV is a virus, like the flu or cold. A virus is really nothing but a set of instructions for making new viruses, wrapped up in some fat, protein and sugar. Without living cells, a virus can't do anything - it's like a brain with no body. HIV damages the human immune system by killing or injuring the immune cells such that the person's body is unable to fight off certain infections and cancers. In order to make more viruses (and to do all of the other nasty things that viruses do), a virus has to infect a cell. HIV mostly infects T-cells, also known as CD4+ cells, or T-helper cells. These cells are white blood cells that turn the immune system on to fight disease. Once inside the cell, HIV starts producing millions of little viruses, which eventually kill the
Biology coursework
Investigating the effect of bead diameter on conversion of sucrose to glucose and fructose by immobilized invertase Hypothesis- I predict that as the invertase beads decrease in diameter, the rate of glucose production will increase. Background Biology Enzymes are protein molecules, which serve to accelerate the chemical reactions of living cells. Without enzymes, most biochemical reactions would be too slow to even carry out life processes. Enzymes display great specificity and are not permanently modified by their participation in reactions. Since they are not changed during the reactions, it is cost-effective to use them more than once. However, if the enzymes are in solution with the reactants and/or products it is difficult to separate them. Therefore, if they can be attached to the reactor in some way, they can be used again after the products have been removed. Specificity Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. Complementary shape, charge and hydrophilic/hydrophobic characteristics of enzymes and substrates are responsible for this specificity, which is often referred to as "the lock and key" model. Immobilized enzymes An immobilized enzyme is an enzyme that is physically attached to a solid support over which a substrate is passed and converted to product. There are
Biology Coursework Investigation
Biology Coursework Investigation Aim The aim of my experiment is to investigate how long is needed to digest starch using the enzyme amylase at different temperatures. Introduction I am investigating the time needed for enzymes at different temperatures to digest starch. Enzymes are small protein molecules made in the pancreas and stored in the stomach. They are a biological catalyst that means they increase the rate of reaction in digestion. For enzymes to digest they need to be denatured; this is the term used to describe when enzymes are heated to reach their optimum temperature; when the enzyme is heated over its optimum temperature its bonds are broken and the shape of its active site changes therefore preventing the substrate from fitting into it, as each substrate is specific to one enzyme it will therefore stop reacting. After the enzyme is denatured it can never return to its previous state and because enzymes have a high specificity they can only catalyse one reaction. I am going to test for starch using iodine, when the iodine turns brown this will indicate that the starch is digested. Variables A variable is anything you can measure or change in an experiment. In this investigation there are certain variables, which must be taken into consideration before carrying out the experiment. These include: - The pH of the experiment (input variable) - If the pH is
Biology Coursework on Enzymes.
Biology Coursework on Enzymes Name: Brijel Limbachia Form: 12.92 Teachers: Mr Lotsu and Mrs Stewart Enzymes in General I will first of all talk about enzymes in general. This means that I will talk about what enzymes are, how being in certain conditions affects the enzyme itself. I will also talk about how substances can increase the % transmission between the enzyme and the substrate. What are enzymes? The catalysis that takes place in organisms is defined as the acceleration of a chemical reaction by some substance which itself undergoes no permanent chemical change. These kinds of catalysts, which are in biochemical reactions, are called enzymes. Enzymes are responsible for almost all of the chemical reactions in living organisms. Without enzymes, these reactions take place at a rate that is far too slow for the pace of metabolism. An active enzyme could make a certain reaction speed up, but not all living things need all the reactions to be quick all the time. It's more accurate to say that enzymes react with simpler molecules to produce a stable reaction system in which the products of any reaction are made when they are needed, also in the amount that they are needed. All known enzymes are proteins. Enzymes are high molecular weight compounds made up of chains of amino acids that are linked together by peptide bonds. As you know that enzymes are composed of
