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Biology Assignment

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Biology Assignment Enzymes * Enzymes are globular proteins that act as biological catalysts. * They speed up chemical reactions that would otherwise occur very slowly at the temperature within cells. * The precise three-dimensional enzyme has a depression on its surface called the active site. This site may be a relatively small part of the large protein. * Only a few amino acids may be directly involved in the active site, with the remainder of the molecule maintaining the three dimensional shape of the protein molecule. ...read more.


* When the reaction has taken place the products are released, leaving the enzyme unchanged. * The substrate is often likened to a key, which fits into the enzyme lock, so this is known as the lock and key of enzyme reaction. * Each enzyme will only catalyse one specific reaction because of its precisely shaped active site. Finding rates of enzyme-controlled reactions The rate of reaction is measured by determining the quantity of substrate used, or the quantity of a product formed in a given time. ...read more.


The slope of the rapid phase of this reaction is known as the initial rate of reaction. How do enzyme and substrate concentrations affect the rate of reaction? In A, the initial rate of reaction is directly proportional to the enzyme concentration because there are more enzymes present, so there are more active sites that are available to form enzyme substrate complexes. The increase it rate will continue because there is an excess amount of the substrate. In B you can see how at high substrate concentrations it is the enzyme concentration that limits the rate of reaction. Every active site is occupied and substrate molecules cannot enter an active site until one becomes free again. Charlotte Johnson HOD ...read more.

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