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What is a Catalyst?

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What is a Catalyst? "A substance, which accelerates or retards a chemical reaction without itself undergoing any permanent chemical change." The New Choice English Dictionary 1999 Enzymes are biological catalysts. There are about 40,000 different enzymes in human cells, each controlling a different chemical reaction. They increase the rate of reactions by a factor of between 106 to 1012 times, allowing the reactions to take place at normal temperatures. Eduard Buchner discovered them in 1900 in fermenting yeast. The name enzyme means "in yeast". Enzymes are proteins, and their function is determined by their complex globular three-dimensional structure. "Typically enzymes speed up a chemical reaction between one million (106) and one trillion (1012) times- the equivalent of accelerating a life span of 100 years into the space of 1 sec". Toole & Toole Understanding Biology for Advanced level 4th Edition 1999 PG 35 www.stratgis.ic.gc.ca./ssgf/0048e.html The reaction takes place in an area of the enzyme named the Active Site, while the rest of the protein acts as "scaffolding". This is shown in the diagram of an enzyme, with a small amount of glucose binding to the active site. The amino acids around the active site attach to the substrate molecule and hold it in position while the reaction takes place. ...read more.


Coenzymes, a non-protein organic substance, which are not bound to the enzyme. Derive from vitamins, Nicotinamide adedinie dinucleotide (NAD) a member of the vitamin b complex. This acts as a coenzyme by acting as a hydrogen acceptor to dehydrogenases. Then there are the Prosthetic Groups, like coenzymes they are organic, but unlike coenzymes they are bound to the enzyme. The best-known group is Haem. These are ring shaped molecules with iron in its centre, which carry oxygen in the haemoglobin, but also it is the prosthetic group of the electron carrier cytocrhome and the enzyme catalase. Inhibitors as their name suggests inhibit the activity of enzymes, reducing the rate of there reactions. They're naturally there, but are also used artificially as drugs and pesticides. There are two kinds of inhibitors. The first being a Competitive Inhibitor. The structure of this molecule is similar to the substrate molecules, it to can fit into the active site. It therefore competes for the active site, so the reaction is slower. If the concentration of substrate is greater than the concentration of inhibitors then the inhibition will be less. http://ntri.tamuk.edu/cell/enzyme2.html A Non Competitive inhibitor molecule is different in structure to the substrate and does not fit the active site. ...read more.


It only reacts with the original antibodies, which are linked to the certain chemical. A substrate is then added which the enzyme causes a change in colour. The amount of the chemical we are looking for is shown by the amount of colour change in the substrate. They come in different forms from urine dipsticks for home pregnancy kits, blood glucose test strips for diabetes and the aids test. Enzymes are used for patients with enzyme deficiencies. An example is in the treatment of haemophilia by administering blood clotting factors or the use of protease to degrade fibrin. The use of protease prevents the formation of dangerous blood clots. The protease used in the therapy of thromboembolic diseases myocardial infarction (TDMI) and deep venous thrombosis is called tissue plasminogen activator. In this assignment we have looked at the biological structure and function of enzymes in the human body and described some of their industrial and medical uses and their source's. It shows the importance to chemical reactions in and out of the body, it also shows exactly what the enzymes need to work quickly and efficiently and what factors contribute to this, and also what factors prevent and disrupt enzyme reactions. Barry Hollinshead, H.E.F.C. Human Biology. Word count 2109 ...read more.

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