Enzymes

Question 1

How do enzymes lower the activation energy in an enzyme-catalysed reaction?

Answer 1

They form temporary bonds between the R groups in an enzyme’s active site and the substrate

Question 2

What is an intracellular enzyme?

Answer 2

• Act within the cells that produce them
• Example is catalase
• Catalase breaks down hydrogen peroxide into water and oxygen

Question 3

What are 2 examples of extracellular enzymes?

Answer 3

• Amylase breaks down starch into maltose
• Trypsin breaks down proteins into smaller polypeptides

Question 4

What happens to enzymes in acidic solutions below their optimum pH, and alkaline above their optimum pH?

Answer 4

Acidic - H+ ions break ionic or hydrogen bonds and denature the enzyme
Alkaline - OH- ions break ionic or hydrogen bonds, denaturing the enzyme

Question 5

What are cofactors and coenzymes?

Answer 5

• Cofactors are non protein substances that bind to enzymes to increase their activity, for example Cl- is a cofactor for the enzyme amylase
• Coenzymes are organic cofactors derived from vitamins

Question 6

What is end-product inhibition?

Answer 6

• Occurs when the product of a reaction acts as an inhibitor to the enzyme that produces it
• Serves as a negative feedback control mechanism for this reaction
• Excess products are not made and resources are not wasted
• An example of non-competitive, reversible inhibition

Question 7

What are prosthetic groups and an example?

Answer 7

• Cofactors that are tightly bound to enzymes
• For example, Zn2+ is a prosthetic group for the enzyme carbonic anhydrase