Enzyme Structure & Function

Question 1

Describe the features of enzymes.

Answer 1

1. Biological catalysts
2. Enable chemical reactions to take place at relatively low temperatures
3. Not used up in chemical reactions
4. Globular proteins with a specific shape

Question 2

Describe the structure of enzymes.

Answer 2

1. Globular proteins with polar R-groups making them soluble
2. Made up of many amino acids joined by peptide bonds in condensation reactions
3. Specific tertiary structure
4. Hydrogen ionic and disulphide bonds hold structure in place
5. Specific active site shape

Question 3

What makes enzymes specific?

Answer 3

Contain a unique active site shape that is complementary in shape to only one substrate

Question 4

How do enzymes function?

Answer 4

1. Specific tertiary structure
2. Specific active site shape
3. Only complementary substrate can bind
4. Forming an enzyme-substrate complex
5. Bonds are either made or broken (condensation/hydrolysis reaction)
6. Products are released from the active site
7. Lower the activation energy

Question 5

Describe the “lock and key” theory

Answer 5

Active site has a fixed shape that does not change after the substrate has bound.

Question 6

Describe the “induced fit” theory

Answer 6

Active site is not complementary to the substrate.
—> as the substrate moves into the active site, the shape changes and becomes complementary
—> bonds are stressed making it easier to break which lowers energy required for the reaction to take place