Enzyme Action 3.0 / 5 based on 1 rating ? BiologyBiological molecules, organic chemistry and biochemistryASAQA Created by: Ellie RiversCreated on: 01-04-13 16:44 Enzymes as Catalysts catalysts alter the rate of reaction without permenantly changing enzymes dont make reactions happen they just alter the speed an inital boost of energy is needed to start the reaction, this is known as ACTIVATION ENERGY enzymes lower the activation energy and and allow the reactions to take place at a lower temperature 1 of 4 Enzyme Structure the enzyme molecule is large, but only a small region is functional this is the ACTIVE SITE, a hollow depression in the larger enzyme molecule the molecule on which the enzyme acts is called a SUBSTRATE this fits neatly into the active site forming an ENZYME SUBSTRATE COMPLEX 2 of 4 Lock and Key Model a substrate will only fit the active site of one particular enzyme enzymes are specific in the reactions that they catalyse the shape of the substrate exactly fits the active site of the enzyme one limitation is that the active site is a rigid structure 3 of 4 Induced Fit Model rather than being rigid, the enzyme changes its shape slightly to fit the substrate the enzyme is flexible and can mould itself the enzyme has a general shape but alters in the presence of a substrate the change in shape puts pressure on the substrate this strain distorts the bond and lowers the activation energy needed to break the bond and change in the enzymes environment is likely to change its shape 4 of 4
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