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Enzymes are biological catalysts which alters the rate
of a chemical reaction/ is involved in but unchanged
by the chemical reaction it catalyses
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They can be used repeatedly =
effective in small amounts
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Enzymes lower activation energy by
forming enzyme-substrate complexes
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(cellular respiration)

The time taken for the appearance of product / disappearance of substrate is a measure of the rate of an enzyme-controlled reaction
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The rate of reaction can be measured as the time taken
for the reaction mixture to change
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Enzyme action may be extracellular: catalyse reactions outside the cell
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Induced Fit Theory:

The active site and substrate are only complementary after
binding has taken place
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The shape of an enzyme is the result of it’s tertiary structure
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A non-competitive inhibitor is a substance that combines with
some part of an enzyme molecule other than its active site
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The inhibition may be:

Temperature:
Once an enzyme reaches it’s optimum temperature, any further increase causes a decrease in
the rate of reaction
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Reversible: breaking the inhibitor-enzyme complex
is possible
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pH:
A change of pH from the optimum for a particular enzyme alters the electric charge carried
by the amino acid units forming the active site
= enzyme denatured = no longer complementary with substrate
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Inhibitor isn't permanently bound to active site =
when it leaves, either a substrate or inhibitor can take its place
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Increasing the enzyme concentration provides
more active sites so the rate of enzyme activity increases as long as the substrate is present in excess
(more than enough)
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An allosteric Inhibitor is a substance that reversibly
combines with the allosteric site
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(its shape is similar to substrate)
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If there is excess of the enzyme = ROR
is directly proportional to concentration of substrate
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A metabolic pathway is a sequence of reactions where a particular molecule is converted into another different one by way of a
series of intermediate compounds

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