2.1.4: Enzymes

Question 1

What is the term for a substance that decreases the rate of reaction by binding to the active site of an enzyme?

Answer 1

Competitive inhibitor

Competitive inhibitors are similar in shape to the substrate and compete for the active site.

Question 2

What forms when a competitive inhibitor binds to an enzyme?

Answer 2

Enzyme-inhibitor complex

This complex prevents the substrate from binding, resulting in a lower rate of reaction.

Question 3

What happens to the reaction rate when substrate concentration is low?

Answer 3

The reaction rate will be lower

This is due to fewer collisions between the enzyme and substrate.

Question 4

What is the effect of increasing substrate concentration on the rate of reaction?

Answer 4

Increases the rate of reaction until it plateaus

At high substrate concentrations, the reaction rate plateaus due to enzyme saturation.

Question 5

What occurs at high enzyme concentrations when substrate is limited?

Answer 5

The rate of reaction plateaus

This happens because there is insufficient substrate to bind with the excess enzymes.

Question 6

Define ‘allosteric site’.

Answer 6

Site on an enzyme where non-competitive inhibitors bind

Binding at the allosteric site changes the shape of the active site.

Question 7

What is a non-competitive inhibitor?

Answer 7

An inhibitor that binds to an allosteric site

Non-competitive inhibitors change the shape of the active site, preventing substrate binding regardless of substrate concentration.

Question 8

True or False: Most competitive inhibitors are irreversible.

Answer 8

False

Most competitive inhibitors are reversible and can be displaced by high concentrations of substrate.

Question 9

At what point does the rate of reaction plateau?

Answer 9

When all enzyme active sites are in use

This indicates that the enzymes are saturated with substrate.

Question 10

Fill in the blank: Increasing _______ concentration will increase the rate of reaction.

Answer 10

enzyme

More enzyme-substrate complexes are likely to form with increased enzyme concentration.

Question 11

What is the relationship between enzyme concentration and the formation of enzyme-substrate complexes?

Answer 11

Higher enzyme concentration leads to more enzyme-substrate complexes

This is true until substrate becomes the limiting factor.