3. Enzymes Flashcards
What is an enzyme
A biological catalyst which speeds up a chemical reaction but remains unchanged at the end of the reaction.
Describe the lock and key hypothesis
A hypothesis for enzyme action, the substrate is a complementary shape to the active site of the enzyme, and fits exactly into the site, the enzyme shows specificity for the substrate.
Describe the induced fit hypothesis
A hypothesis for enzyme action, the substrate is a complementary shape to the active site of the enzyme, but not an exact fit- the enzyme, or sometimes the substrate, can change shape slightly to ensure a perfect fit, but is still described as showing specificity
How do enzymes increase the rate of reaction? Describe how this in turn works?
By decreasing the activation energy.
They do this by holding the substrate in a way that their molecules can react more easily.
The rate at which a reaction occurs depends on….?
How many enzyme molecules there are
The speed at which the enzyme can convert the substrate into product, release it, and then bind with another substrate molecule.
What is enzyme affinity
A measure of the strength of attraction between the enzyme and its substrate
Competitive inhibition
When a substance reduces the rate of activity of an enzyme by competing with the substrate molecules for the enzymes active site; increasing substrate concentration reduces the degree of inhibition; increasing inhibitor concentration increases the degree of inhibition
Non-competitive inhibition
When a substance reduces the rate of activity of an enzyme, but increasing the concentration of the substrate does not reduce the degree of inhibition; many non-competitive inhibitors bind to areas of the enzyme molecule other than the active site itself
