Biological molecules 1: Factors affecting enzyme activity

Question 1

What are the factors which affect enzyme activity

Answer 1

Temperature
PH
Substrate concentration
Enzyme concentration
Inhibition

Question 2

How do low temperatures affect enzyme activity

Answer 2

They lead to slower chemical reactions

Question 3

How does increasing temperature to an enzyme’s optimum increase enzyme activity

Answer 3

Enzyme activity increases because more enzyme-substrate complexes form because more heat is introduced meaning more kinetic energy supplied to molecules so they move faster - leading to successful collisions between substrate and enzyme

Question 4

Why does the optimum temperature increase enzyme activity

Answer 4

Because more successful collisions occur between the substrate and the enzyme (forming enzyme-substrate complexes)

Question 5

How does increasing temperature beyond optimum affect enzyme activity

Answer 5

It decreases enzyme activity

Question 6

Why does increasing temperature beyond optimum decrease enzyme activity

Answer 6

Vibrations which are induced by heat breaks the tertiary structure which holds the enzyme in shape meaning its no longer complementary to the substrate as the active site also changes

Question 7

How does the PH increasing/ decreasing away from optimum affect enzyme activity

Answer 7

It decreases enzyme activity

Question 8

Why does the PH increasing/ decreasing away from optimum decrease enzyme activity

Answer 8

The H+ ion found in acids and the OH- ion found in alkali’s disrupt the ionic and hydrogen bonds that holds an enzymes tertiary structure, leaving it denatured because the active site changes

Question 9

How does increasing substrate concentration affect enzyme activity

Answer 9

It increases enzyme activity

Question 10

Why does increasing substrate concentration affect enzyme activity

Answer 10

More substrate molecules means their is a higher chance of successful collisions from occurring between enzyme and substrates to form enzyme-substrate complexes up to a saturation point

Question 11

What happens when substrate concentration reaches a saturation point

Answer 11

The substrate becomes a limiting factor because the active site of the enzymes are all full - and increasing substrate concentration had no further effect

Question 12

How does increasing enzyme concentration affect enzyme activity

Answer 12

It increases enzyme activity

Question 13

Why does increasing enzyme concentration increase enzyme activity

Answer 13

As enzyme concentration increases so does the chance of a substrate successfully colliding with the one to form an enzyme substrate complex

Question 14

What happens if a substrate in a solution is limited

Answer 14

Enough enzymes would be able to react with the available substrate with some enzymes to spare

Question 15

What are the two types of inhibitors

Answer 15

Competitive
Non-competitive

Question 16

How do competitive inhibitors decrease enzyme activity

Answer 16

It slows down the initial rate of reaction by binding to the active size of an enzyme - temporarily blocking substrates from the enzymes and preventing enzyme-substrate complexes from forming

Question 17

What do competitive inhibitors bind to

Answer 17

The active site

Question 18

What do non-competitive inhibitors bind to

Answer 18

The allosteric site (away from the active site)

Question 19

How do non-competitive inhibitors decrease enzyme activity

Answer 19

It slows down the initial rate of reaction by binding to the allosteric size of an enzyme - permanently blocking substrates from the enzymes and preventing enzyme-substrate complexes from forming

Question 20

In terms of the rate of reaction - substrate concentration graph, how will a non competitive affect the curve

Answer 20

The initial rate of reaction would be less steep and the curve would have a lower vmax than if the reaction contained no non-competitive inhibitors

Question 20

In terms of the rate of reaction - substrate concentration graph, how will a competitive affect the curve

Answer 20

The initial rate of reaction would be less steep however the curve would have the same vmax than if the reaction contained no competitive inhibitors