Enzyme Inhibition

Question 1

List the 3 types of enzyme inhibition.

Answer 1

• Competitive
• Uncompetitive
• Mixed

Question 2

How does a competitive inhibitor react to an enzyme?

Answer 2

It binds to the active site and competes with the substrate

Question 3

How does a non-competitive inhibitor react with an enzyme?

Answer 3

It binds to the allosteric site and changes the shape of the active site of the enzyme

Question 4

What is mixed inhibition?

Answer 4

Inhibition where both competitve and uncompetitive inhibition occurs

Question 5

What are cofactors?

Answer 5

Non-protein enzyme helpers

Question 6

What cofactor complexes with methemoglobin?

Answer 6

Fe³⁺

Question 7

What cofactor complexes with hemoglobin?

Answer 7

Fe²⁺

Question 8

Give 3 examples of cofactors.

Answer 8

Zinc, iron, and copper

Question 9

Cofactors can bind …. to the enzyme.

Answer 9

Permanently or reversibly

Question 10

What are coenzymes?

Answer 10

Inorganic cofactors

Question 11

Give some examples of coenzymes.

Answer 11

B Vitamins

Question 12

What cofactor complexes with methemoglobin?

Answer 12

Fe³⁺

Question 13

What is Feedback Inhibition?

Answer 13

It is a process whereby an early step in a metabolic pathway is switched off by the pathway’s final product.

Question 14

Give an example of Feedback Inhibition.

Answer 14

Isoleucine Production

Question 15

What is the substrate used for Isoleucine Production?

Answer 15

Threonine

Question 16

Why is Feedback Inhibition useful for a cell?

Answer 16

It prevents the cell from wasting chemical resources by preventing synthesising more product than is needed.

Question 17

What is Allosteric Regulation?

Answer 17

This is when a protein’s function at one site is affected by the binding of a regulatory molecule at another site.

Question 18

Most allosterically-regulated enzymes consist of how many polypeptides?

Answer 18

2 or more

Question 19

How does an activator affect an enzyme?

Answer 19

It stabilises the active form of the enzyme by binding to the allosteric/ regulatory site.

Question 20

How does an inhibitor affect an enzyme?

Answer 20

It stabilises the inactive form of the enzyme by binding to its allosteric/ regulatory site.

Question 21

What is co-operativity?

Answer 21

A form of allosteric regulation that can increase enzyme activity.

Question 22

How does co-operativity work?

Answer 22

A substrate binds to an active site on one of the subunits of the active form of enzyme, which locks all the subunits into the active conformation.