Unit 2.4-Enzymes

Question 1

What types of reactions do enzymes help with?

Answer 1

• Catabolic reactions

- Anabolic reactions

Question 2

Catabolic reactions definition:

Answer 2

Molecules are broken down into smaller ones and release energy

Question 3

Anabolic reactions definition:

Answer 3

Energy is used to synthesize larger molecules from smaller ones

Question 4

What are examples of extra cellular enzymes?

Answer 4

• Fungi
• Digestive enzymes
• Amalayse - turns starch into maltose
• Trypsin - made in the pancreas, turns proteins into smaller polypeptides. The optimum PH is 7.5 - 8.5

Question 5

Cofactors definition:

Answer 5

A substance that has to be present to ensure that an enzyme catalyzed reaction takes place at the appropriate rate

Question 6

What are the opposite to cofactors?

Answer 6

Inhibitors

Question 7

What does the graph for temperature and rate of reaction look like?

Answer 7

Upside down U

Question 8

How does temperature affect the rate of reaction of enzymes?

Answer 8

When temperature increases, rate of reaction increases because the enzymes and substrates have more kinetic energy so move around faster, so there are more successful collisions

Question 9

What happens after the optimum temperature for enzyme reactions is met?

Answer 9

The enzyme is denatured and the active site changes shape because the particles are changing position and moving apart, causing the active site to change shape.

Question 10

What does the graph for PH and rate of reaction look like?

Answer 10

Upside down U but skinny

Question 11

What is a buffer?

Answer 11

It resists changes in PH by donating or accepting H+ or OH- ions

Question 12

What type of ions do acids have?

Answer 12

H+

Question 13

What type of ions do alkalines have?

Answer 13

OH-

Question 14

What happens to rate of reaction with enzymes when there is not much change from the optimum PH?

Answer 14

Hydrogen or ionic bonds can be restored when PH is restored, so the rate of reaction can increase up to the maximum

Question 15

What happens to rate of reaction with enzymes when there is a lot of change from the optimum PH?

Answer 15

The bonding changes and the tertiary structure and active site are completely changed so the enzyme is denatured.

Question 16

What does the graph for substrate concentration and rate of reaction look like?

Answer 16

Increases then plateaus

Question 17

How does substrate concentration affect the rate of reaction?

Answer 17

Increased substrate concentration causes increased rate of reaction up to a point. After that, the concentration of substrates is no longer the limiting factor, something else is.

Question 18

What do competitive inhibitors do?

Answer 18

Block the active site by fitting into it

Question 19

What do non-competitive inhibitors do?

Answer 19

Bind to the enzyme (not in the active site) and change its tertiary structure so a substrate can’t fit into the active site

Question 20

What does the graph look like for non-competitive inhibitors and rate of reaction?

Answer 20

The line goes up then plateaus but is much lower than it would be without the inhibitors

Question 21

What does the graph look like for competitive inhibitors and rate of reaction?

Answer 21

The original line goes up then plateaus. The inhibitors line cuts across the bend, so is slightly lower