GCSE Biology Enzymes




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  • Created on: 28-02-10 23:35
Preview of GCSE Biology Enzymes

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Enzymes speed up a reaction.
They have specific shapes and only works on one substance.
Amylase speeds up the breakdown of starch into sugar maltose.
The substrate fits into a region in the enzyme called the active site. The active site is a certain size
and therefore will only let particular molecules in it. When in the active site the two join together
which is called the enzyme-substrate complex.
Enzyme Substrate Product
Lipase Fats and oils Glycerol and Fatty acids
Amylase Starch Maltose
Maltase Maltose Glucose
Pepsin Protein Polypeptides
Protease Polypeptides Amino Acids
Catalase Hydrogen Peroxide Water + Oxygen
The optimum temperature for each enzyme is different.
Rate of
5 37 95
The enzymes work best at different temperatures. Humans temperatures are 37* and that's where
our enzymes work best.
Concentration also affects enzymes.
If you increase the concentration then the rate of enzymes increases because there are more
molecules for the enzyme to join onto. If there are very few substrate particles it will take a lot of
time for it to bump into an enzyme. But there comes a point where you cannot increase the rate
anymore. The enzyme is working as fast as it can and so a graph is shown like this...
Rate of
Substrate Concentration

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Ph affects the rate of enzymes. Most enzymes work best at neutral Ph and changing the Ph either
way by one unit usually stops the enzyme working. For example Amylase works best in a Ph of 7.5
so placing it in a solution greater than 8.5 or lower than 6.5 will stop it working. Pepsin works in the
stomach and so works best in Ph2.…read more


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