2.5 Enzymes

Question 1

What is a substrate?

Answer 1

The substance that an enzyme converts into products in a catalyzed reaction

Question 2

What is an active site?

Answer 2

A special region on the surface of the enzyme to which the substrate(s) bind. Enzyme-substrate specificity exists due to matching shapes.

Question 3

How do catalysts work?

Answer 3

They lower the activation rate of a reaction and speed up the reactions without being altered themselves.

Question 4

What is activation energy?

Answer 4

The energy needed to be gained by the reactant before the reaction can start. Energy is used to break bonds within reactant

Question 5

What are the 3 stages of enzyme activity?

Answer 5

1. Substrate binds to active site
2. While bound, changes into products
3. Products separate from active site, leaving it vacant to be used again

Can only bind to active site if moves close to it - random movements

Question 6

What is an allosteric site?

Answer 6

A site on the enzyme separate from the active site to which the allosteric regulator binds.

Question 7

What is an inhibitor

Answer 7

When the allosteric regulator binds to the allosteric site, there is a conformational change in the active site so the substrate cannot bind to it.

Question 8

What is an activator

Answer 8

When the allosteric regulator binds to the allosteric site there is a conformational change in the active site so the substrate can bind to it

Question 9

What three things affect the rate of activity of enzymes?

Answer 9

Temperature, pH, substrate concentration. Enzymes can be denatured by overheating or increases and decreases from optimum pH

Question 10

What is immobilization of an enzyme?

Answer 10

Enzymes are immobilized to restrict their movement to keep them separate from other products, recycled easily, increase their stability to changes in temp and pH, and create faster reactions.

Question 11

What are the uses of lactase (enzyme) in food processing?

Answer 11

Creation of lactose-free milk, galactose and glucose sweeter than lactose so less sugar needs to be added to foods, g and g more soluble so remain dissolved when making ice cream, production of yogurt and cottage cheese is faster due to bacteria fermenting sugars faster.

Question 12

What are enzymes?

Answer 12

Globular proteins that work as catalysts