Enzymes

Question 1

What are anabolic reactions?

Answer 1

Reactions that build up molecules

Question 2

What are catabolic reactions?

Answer 2

Reactions that break down molecules

Question 3

What is metabolism?

Answer 3

The sum of all the anabolic and catabolic reactions

Question 4

What is a catalyst?

Answer 4

A substances that speeds up the rate of a reaction without changing the produced substances

Question 5

What is a metabolic pathway?

Answer 5

A sequence of enzyme controlled reactions

Question 6

What is specificity?

Answer 6

When an enzyme can only catalyse specific reactions

Question 7

What is the substrate?

Answer 7

The molecule the enzymes works on

Question 8

What is a product

Answer 8

Molecule produced by enzyme

Question 9

What is the induced fit hypothesis?

Answer 9

That the substrate and active site are only fully complimentary after the substrate is bound

Question 10

How do enzymes catalyse a reaction?

Answer 10

They lower the activation energy

Question 11

How does low temperature affect rate of reaction?

Answer 11

The rate of reaction is low because the particles have very little kinetic energy and therefore there are less successful collisions and less product formed

Question 12

How does the optimum temperature affect rate of reaction?

Answer 12

The rate of reaction is fast because the enzymes and substrates have a lot of kinetic energy and therefore there are more successful collisions

Question 13

How does high temperature affect rate of reaction?

Answer 13

The rate of reaction is low because the enzymes denature as the bonds holding the proteins in place break and cause the active site to change shape. Therefore there are less enzymes to catalyse the reaction so there are less successful collisions

Question 14

How does low pH affect rate of reaction?

Answer 14

The rate of reaction is low because there is a higher concentration of H+ ions which means that the R groups are less able to interact so the active site of the enzymes changes shape. Therefore there are less enzymes to catalyse the reaction so there are less successful collisions

Question 15

How does the optimum pH affect the rate of reaction?

Answer 15

The rate of reaction is fast because the conc. of H+ ions is perfect for the active site of the enzymes therefore there is a higher frequency of successful collisions

Question 16

How does high pH affect the rate of reaction?

Answer 16

Rate of reaction is low because there are more OH- ions present which causes the R groups to interact less and therefore the active site changes shape. So, there are less successful collisions

Question 17

How does low substrate concentration affect the rate of reaction?

Answer 17

The rate of reaction is low because there are less substrates in the same area and therefore there are less successful collisions

Question 18

How does the optimum substrate concentration affect the rate of reaction?

Answer 18

The rate of reaction is fast because there are more substrates in the same area which means there are more successful collisions

Question 19

How does high substrate concentration affect the rate of reaction?

Answer 19

The rate of reaction is constant because all of the active sites are occupied by substrate particles

Question 20

How do competitive inhibitors affect enzyme function?

Answer 20

The molecule has a similar shape to the substrate of the enzyme so it competes with the substrate for the active site. This blocks the substrate from binding to the active site. This results in less successful collisions and a lower rate of reaction at LOW substrate concentration

Question 21

How do non- competitive inhibitors affect enzyme function?

Answer 21

The substrate can still bind to the active site. However, the inhibitor attaches onto the enzyme and changes the shape of the active site so induced fit cannot occur. This results in less successful collisions and therefore reduces the rate of reaction.

Question 22

Why does the rate of reaction never meet the V Max with non-competitive enzymes?

Answer 22

Because the enzyme and substrate still have a lower frequency of successful collisions because the enzymes with inhibitors do not convert substrate to product

Question 23

Why can the rate of reaction with competitive enzymes reach the V Max at higher concentration?

Answer 23

Because the inhibitor is out-competed by the substrate and therefore the rate of reaction can increase to the V Max

Question 24

What is a cofactor?

Answer 24

A non-protein chemical compound or metallic ion that is required for an enzyme’s activity as a catalyst

Question 25

What is a coenzyme?

Answer 25

Cofactors which are organic- carbon based

Question 26

Where are coenzymes derived from?

Answer 26

They are often derived from vitamins

Question 27

How are enzymes named?

Answer 27

They are classified according to the type of chemical reactions that they catalyse. For example, hydrolases are enzymes that hydrolyse reactions.