What are enzymes?
Enzymes What are enzymes? Enzymes are biological catalysts they alter the rate of reaction without it self being used up or changed during the reaction. Without enzymes the reactions that take place in an organism would be too slow for life to continue. Enzymes are proteins and how an enzyme functions is determined by its three dimensional structure. An enzyme has: > Three dimensional shape > Area on its surface called Active site The substance that the enzyme helps to react is called the substrate. Substrate has complementary to the active site and the substrate fits into the active site. The active site of each of each different enzyme has its own particular three-dimensional shape so only a substrate with a complementary shape will fit it. Most enzymes catalyse speed up only one reaction or one group of reactions. Below shows the break down Maltose to Glucose Maltase + Maltose = Maltase + Glucose In the above reaction Maltose is the substrate and Maltase is the enzyme and the product formed is Glucose. Maltase will only speed up the break down of Maltose to Glucose it does not act on ant other substrate. How they work? Like all other particles in the cell Enzyme molecules are constantly moving about colliding with other molecules. When an enzyme molecule collides with its substrate molecule the substrate binds to the enzymes active site. The substrate when
What are 'Enzymes'?
Enzymes Enzymes are proteins and are biological catalysts. They speed up chemical reactions that happen within living things. They are very efficient at doing their job. To give you an idea of efficiency one catalase molecule can break six million hydrogen peroxide molecules into harmless water and oxygen per minute. There are two types of enzymes extracellular enzymes and intracellular enzymes. Extracellular enzymes are made inside cells, once formed they may move out and do its job outside of the cell an example of extracellular enzymes is the enzymes in the digestive system. Intracellular enzymes are also produced inside the cell, however they work within the cell speeding up the chemical reactions they can also control reactions. An example of an enzyme-controlled reaction is: Maltase (enzyme) Maltose (substrate) Glucose (product) The substance that the enzyme acts on (Maltose) is called the substrate. The new substance(s) formed is called the product(s). This reaction, along with many metabolic reactions, is reversible meaning maltose can become glucose or glucose can become maltose. They way the reactions turns depends on the proportions of glucose to maltose. If there is a lot of maltose and little glucose then the reaction will be as above but if there is less maltose than glucose then it will go
What are 'Enzymes'?
Enzymes Enzymes are catalysts. Most are proteins. (A few rib nucleoprotein enzymes have been discovered and, for some of these, the catalytic activity is in the RNA part rather than the protein part. Link to discussion of these ribozymes.) Enzymes bind temporarily to one or more of the reactants of the reaction they catalyses. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Examples: * Catalyse. It catalyses the decomposition of hydrogen peroxide into water and oxygen. 2H2O2 -> 2H2O + O2 One molecule of catalyse can break 40 million molecules of hydrogen peroxide each second. * Carbonic anhydrase. It is found in red blood cells where it catalysis the reaction CO2 + H2O <-> H2CO3 It enables red blood cells to transport carbon dioxide from the tissues to the lungs. One molecule of carbonic anhydrase can process one million molecules of CO2 each second. * Acetylcholinesterase. It catalysis the breakdown of the neurotransmitter acetylcholine at several types of synapses as well as at the neuromuscular junction - the specialized synapse that triggers the contraction of skeletal muscle. One molecule of acetyl cholinesterase breaks down 25,000 molecules of acetylcholine each second. This speed makes possible the rapid "resetting" of the synapse for transmission of another nerve impulse. Most of these interactions
What is Homeostasis?
HOMEOSTATSIS Homeostasis is a very important biological function that occurs in all endotherms but not ectotherms. Endotherms have the ability to adjust their body temperature: they are not dependent on the surrounding temperature of the environment. Examples of endotherms are mammals: humans. Homeostasis works by using a process called negative feedback which works by adjusting a condition in the body so that the internal environment stays, on average, the same. It works using nerves. A receptor detects the change in the surrounding environment and sends nerve impulses to the centres in the brain, such as the medulla, which sends nerve impulses to glands or muscles to bring about an effect which will lower or increase a condition in the internal environment to keep it within certain limits. Homeostasis is used to control body temperature, blood glucose concentration and the water content of the blood. The body temperature in endotherms is controlled by dilation and contraction of arterioles, sweat and contraction of the erector pili muscles. This is called thermoregulation. When the temperature of the surrounding environment increases the internal environment must be decreased. To do this the arterioles dilate (vasodilation) so that more blood flows through the capillaries next to the skins surface. This means more heat can be released through the skin as the blood is
Why does the colour leak out of cooked beetroot?
Why does the colour leak out of cooked beetroot? Aim: To investigate the effect of temperature on membrane structure Introduction: I will be measuring the amount of light absorbed by the pigment in the beetroot, which will tell me how much dye has been released from the beetroot. My null hypothesis (H?) is: no matter what the temperature increase, the amount of dye being released from the beetroot will remain the same. My alternate hypothesis (H1) is: an increase in temperature will cause an increase in the amount of dye being released from the beetroot. Beetroot cells, like any other cells with membranes, have many types of cells with special functions. Some of these organelles are bounded by a single membrane, eg. vacuole, and some are bounded by two membranes e.g. nucleus, mitochondrion. Beetroot appears as a dark red/ purple colour and this is caused by the betalain pigment, which is contained within the vacuole of the beetroot cells. In order for the betalain to leave the cell it needs to pass through two different membranes; the membrane bounding the vacuole and the membrane enclosing the cell. An increase in temperature will damage and denature the membranes and cause the betalain to leak out. Variables: My independent variable is the temperature at which I am heating the beetroot, whilst my dependant variable is the amount of light absorbed by the pigment. I
