8.1 Metabolism (AHL Enzymes)

Question 1

Define metabolic pathway.

Answer 1

A chain or cycle of enzyme-controlled reactions.

Question 2

What effect does an enzyme have on the activation energy?

Answer 2

When an enzyme catalyzes a reaction, the substrate binds to the active site and is altered to reach the transition state. It is this binding that the lowers the energy level of the transition state and thus the activation energy because the enzyme weakens the bonds in the substrate.

Question 3

Differentiate between competitive and non-competitive inhibitors?

Answer 3

Competitive: inhibitor binds to the active site, blocking the active site
Non-competitive: inhibitor binds to the allosteric site, changing the shape of the active site

Question 4

Define allosteric site.

Answer 4

The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of th enzyme and influencing its ability to be active.

Question 5

Which type of inhibitor is more effective? Why?

Answer 5

Non-competitive inhibitors are more effective because, unlike competitive ones, non-competitive inhibitors usually stay bound to the enzyme.

Question 6

How can metabolic pathways be controlled by end-product inhibition?

Answer 6

The end product works as a non-competitive inhibitor on one of the previous products in the metabolic pathway, ending the pathway and preventing further production of the end-product.