key concepts ++ enzyme action

Question 1

what is enzyme specificity ?

Answer 1

Specificity is a property of the enzyme and describes how restrictive the enzyme is in its choice of substrate; a completely specific enzyme would have only one substrate. The shape of the active site of an enzyme is complementary to the shape of its specific substrate. This means they are the correct shapes to fit together

Question 2

what is an enzyme’s action due to ?

Answer 2

an enzyme’s action is due to its active site

Question 3

describe the role of the active site in enzyme function (including specificity)

Answer 3

active site refers to the part of the enzyme to which a specific substrate can attach or fit on to.

Question 4

use the lock-and-key model to develop explanations for enzyme activity

Answer 4

The lock and key mechanism is a metaphor to explain the specificity of the enzymes active site and the substrate. In the same way only certain keys fit a lock, only certain substrates fit an enzyme’s active site. When the correct substrate binds to the enzyme’s active site, an Enzyme substrate complex is formed.

Question 5

explain why enzymes have a particular shape, as a result of the sequence of amino acids in the chain

Answer 5

Proteins are chains of amino acids joined end to end. This chain is not straight – it twists and folds as different amino acids in the chain are attracted to, or repel each other. Each enzyme is comprised of proteins made of these twisting and folding amino acids, and therefore the enzyme has a unique shape

Question 6

explain how enzymes become denatured

Answer 6

If enzymes are exposed to extremes of pH or high temperatures the shape of their active site may change. If this happens then the substrate will no longer fit into the enzymes. This means the key will no longer fit the lock. We say that the enzyme has been denatured.