Topic 1a- Enzyme Action

Question 1

What is an enzyme?

Answer 1

Enzymes speed up chemical reactions by acting as biological catalysts.

Question 2

What is the name given to the amount of energy needed to start a reaction?

Answer 2

Activation energy

Question 3

What is an enzyme-substrate complex?

Answer 3

When a substrate fits into the enzyme’s active site. It lowers the activation energy.

Question 4

Why can an enzyme only bind to one substance?

Answer 4

Enzymes are specific to substrates because they have an active site which only allows certain substrates to bind to it.

Question 5

Describe the ‘induced fit’ model of enzyme action.

Answer 5

The complementary substrate binds to the active site of the enzyme, to form an enzyme-substrate complex. As the substrate binds, the active site changes shape slightly, which provides a better fit. The substrate is broken down / joined together to form the products.

Question 6

Explain how a change in the amino acid sequence may prevent it from functioning properly.

Answer 6

A change in the amino acid sequence of an enzyme may alter it’s tertiary structure. This changes the shape of the active site so that the substance can’t bind to it.