Enzymes

Question 1

What are extracellular enzymes?

Answer 1

Enzymes that work outside the cell.

Question 2

Give an example of an intracellular enzyme, what does it do?

Answer 2

Catalase. It catalyses the breakdown of hydrogen peroxide into oxygen and water.

Question 3

Give two examples of extracellular enzymes?

Answer 3

Amylase and Trypsin

Question 4

Where is amylase found and what is its function?

Answer 4

It is found in saliva. It catalyses the hydrolysis of starch into maltose.

Question 5

Where is trypsin found and what is its function?

Answer 5

It is found in the small intestine produced by pancreatic cells. It catalyses the hydrolysis of peptide bonds making polypeptides into smaller ones.

Question 6

What are enzymes?

Answer 6

They are biological catalysts that speed up metabolic reactions in a cell or organism.

Question 7

What is the active site?

Answer 7

Part of an enzyme that substrate molecules bind to.

Question 8

What is the active site’s shape based on?

Answer 8

The tertiary structure of that enzyme.

Question 9

The active site and substrate molecules are what to eachother?

Answer 9

Complementary.

Question 10

What is activation energy?

Answer 10

The energy required for a chemical reaction to start.

Question 11

How do enzymes speed up reactions in the body?

Answer 11

They reduce the overall activation energy by the formation of the enzyme-substrate complex.

Question 12

What are the two hypothesise for how enzymes work?

Answer 12

Lock and key hypothesis

Induced-Fit hypothesis.

Question 13

Describe the lock and key hypothesis.

Answer 13

Only a specific substrate can enter the active site of an enzyme in the same way that a specific key fits into a lock.

Question 14

Describe the induced-fit hypothesis.

Answer 14

The active site of an enzyme changes shape slightly as the substrate molecule enters.

Question 15

What are the four factors that affect enzyme activity?

Answer 15

Temperature
pH
Enzyme concentration
Substrate concentration

Question 16

How does an increase in temperature affect the rate of an enzymes activity?

Answer 16

More heat means more kinetic energy so particles move faster and collide more frequently. This increases the chance of successful interactions between substrate and active site.

Question 17

How is an enzyme denatured by high temperatures?

Answer 17

The vibrations become too strong and cause the bonds holding the active site to break. This changes the shape of the active site, so it can no longer do its job.

Question 18

What does the temperature coefficient, Q10, mean?

Answer 18

It shows how much the rate of reaction changes when the temperature is raised by 10 *C

Question 19

What is it called when an enzyme and subtracted bind together?

Answer 19

Enzyme-substrate complex.

Question 20

What is the optimum pH value of an enzyme?

Answer 20

The pH at which enzymes work their best.

Question 21

What pH does the enzyme Pepsin work best at?

Answer 21

pH 2 (same as stomach acid)

Question 22

How are enzymes denatured by pH levels?

Answer 22

pH too high/low means that the H+ and OH- ions interfere with the bonds holding the tertiary structure together.

Question 23

How does enzyme concentration increase rate of reaction?

Answer 23

Increases the chance of successful collisions between substrate and enzyme as there are more free active sites to be filled.

Question 24

How does substrate concentration increase the rate of reaction?

Answer 24

More substrates means more collisions as more active sites are being filled.

Question 25

What is saturation point?

Answer 25

The point when all active sites are full so adding more substrates won't make a difference to the rate of reaction.

Question 26

What are intracellular enzymes?

Answer 26

Enzymes that work inside the cell.

Question 27

What are inhibitors?

Answer 27

Molecules that prevent enzymes from catalysing reactions.

Question 28

What are the two types of enzyme inhibitors?

Answer 28

Competitive and non-competitive.

Question 29

What is competitive inhibition?

Answer 29

When the inhibitor compete with the substrate molecules for the active site.

Question 30

What shape are competitive inhibitors?

Answer 30

They have a similar shape to the substrate molecule.

Question 31

How do you competitive inhibitors decrease the rate of reaction?

Answer 31

They bind to the enzyme and block the active site which stops the substrate from entering it.

Question 32

What is non-competitive inhibition?

Answer 32

When the inhibitor binds to the allosteric site making the active site change shape.

Question 33

How do non-competitive inhibitors decrease the rate of reaction?

Answer 33

They change the shape of the active site which prevents substrate molecules from binding to it.

Question 34

When is an inhibitor reversible?

Answer 34

When there are weak bonds between the enzyme and inhibitor it means it can be removed. Binds loosely.

Question 35

When is an inhibitor non-reversible?

Answer 35

When there are strong covalent bonds between the enzyme and inhibitor it means it cannot be removed easily. Binds tightly.

Question 36

What is end-product inhibition?

Answer 36

When the product of a reaction acts as an inhibitor to the enzyme that produces it.

Question 37

What is an anabolic reaction?

Answer 37

Chemical reactions that are required for growth and build up of organisms

Question 38

What are catabolic reactions?

Answer 38

Chemical reactions that breakdown large molecules, like glucose, releasing energy that is required for all processes. Usually done by digestion.

Question 39

What is metabolism?

Answer 39

The sum of all the different reactions and reaction pathways that happen in a cell.

Question 40

What are cofactors and coenzymes?

Answer 40

A non-protein component required by enzymes to carry out their function properly.

Question 41

Give an example of a cofactor?

Answer 41

Minerals and ions like Cl- Zn2+ Ca2+ | Chloride ions are cofactors for Amylase.

Question 42

Give an example of a coenzyme?

Answer 42

Vitamin B5 used for coenzyme A.

Question 43

What is the main difference between cofactors and coenzymes?

Answer 43

Cofactors are in organic and coenzymes are organic.

Question 44

What are prosthetic groups?

Answer 44

Like cofactors, they are needed by enzymes to carry out their function.

Question 45

Give an example of a prosthetic group?

Answer 45

Zn2+ ions are a prosthetic group for carbonic anhydrase (an enzyme used to catalyse the production of carbonic acid from water and carbon dioxide.)

Question 46

What is it about prosthetic groups, that is different from cofactors?

Answer 46

They bind tightly and become a permanent part of the enzyme.