Enzymes

Question 1

What do enzymes do to reactions

Answer 1

Catalyse them

Question 2

Are enzymes globular or fibrous proteins

Answer 2

Globular

Question 3

What is meant by the specificity of enzymes

Answer 3

Which biochemical reaction is catalysed by the enzyme

Question 4

What are anabolic reactions

Answer 4

Where smaller molecules are joined together to make a larger one

Question 5

What are catabolic reactions

Answer 5

Where larger molecules are broken down to form smaller ones

Question 6

Which out of anabolic and catabolic reactions are catalysed by enzymes

Answer 6

Both

Question 7

What is metabolism

Answer 7

Metabolism is the sum of all of the different reactions and reaction pathways happening in a cell or an organism, and it can only happen as a result of the control and order imposed by enzymes

Question 8

What factors affect reaction rate

Answer 8

Temperature
Pressure
pH

Question 9

What is Vmax of a reaction

Answer 9

The maximum rate of reaction

Question 10

What is activation energy

Answer 10

The minimum amount of energy required for a reaction to occur

Question 11

What are the 2 ways that enzymes reduce the required activation energy

Answer 11

Lock and key hypothesis
Induced-fit hypothesis

Question 12

What is formed when enzymes and substrates join together

Answer 12

An enzyme-substrate complex

Question 13

What do intracellular enzymes do

Answer 13

aid metabolic processes inside of both prokaryotes and eukaryotes

Question 14

An example of an intracellular enzyme and what it does

Answer 14

Catalase ensures that hydrogen peroxide is broken down into oxygen and water, therefore preventing its accumulation

Question 15

What do extracellular enzymes do

Answer 15

Break down larger nutrient molecules into smaller molecules in the process of digestion

Question 16

An example of an extracellular enzyme and what it does

Answer 16

Amylase begins the digestion of starch in the mouth

Question 17

What does trypsin do

Answer 17

An enzyme that catalyses the digestion of proteins into smaller peptides which can then be broken down further by other proteases

Question 18

What factors affect enzyme activity

Answer 18

Temperature
pH
Enzyme and substrate concentration

Question 19

What is temperature coefficient (Q10)

Answer 19

A measure of how much the rate of reaction increases with a 10 degree rise in temperature

Question 20

What is Q10 usually for an enzyme-controlled reaction

Answer 20

Usually around 2

Question 21

How are enzymes working at colder temperatures adapted

Answer 21

They are more flexible, especially at the active site. However it makes them more vulnerable to smaller temperature changes

Question 22

How are enzymes working at warmer temperatures adapted

Answer 22

The enzymes are more stable due to an increased number of bonds, particularly hydrogen and disulphide bonds

Question 23

Why does pH affect the shape of enzymes

Answer 23

A change in the concentration of H+ ions and OH- ions interfere with the shape of the tertiary structure

Question 24

Why is it important to control metabolic activity within cells

Answer 24

Important to regulate the rate and quantity of product formation

Question 25

What effects does a competitive inhibitor have

Answer 25

Slows down the rate of reaction however does not impact the Vmax of a reaction

Question 26

How can the effects of a competitive inhibitor be reduced

Answer 26

Add more substrate

Question 27

What site does non-competitive inhibitors bind to

Answer 27

Allosteric site

Question 28

How does a non-competitive inhibitor work

Answer 28

Binds to the allosteric site which causes the tertiary shape of the enzyme to change, therefore the shape of the active site changes

Question 29

Example of irreversible non-competitive inhibitors

Answer 29

Proton pump inhibitors (PPIs) are used to treat long term indigestion. They irreversibly block an enzyme system responsible for secreting hydrogen ions into the stomach

Question 30

What is end-product inhibition

Answer 30

When the product at the end of an enzyme-controlled reaction acts as an inhibitor to the enzyme that produces it

Question 31

What kind of a feedback cycle is end-product inhibition

Answer 31

Negative feedback

Question 32

What is an example of a reversible non-competitive inhibition

Answer 32

End-product inhibition

Question 33

What is a cofactor

Answer 33

A cofactor is a substance that has to be present to ensure that an enzyme-catalysed reaction that takes place at the appropriate rate

Question 34

What is a prosthetic group

Answer 34

Cofactors that are permanently bound to the protein

Question 35

Example of a prosthetic group

Answer 35

Zn2+ ion in carbonic anhydrase, which is an enzyme necessary for the metabolism of carbon dioxide

Question 36

Why can’t the inhibitor be removed easily in a non-competitive inhibition

Answer 36

Strong covalent bonds are formed

Question 37

Why can the inhibitor be removed more easily in a competitive inhibition

Answer 37

Weaker hydrogen or ionic bonds are formed

Question 37

What are inactive precursor enzymes

Answer 37

Enzymes that are produced in an inactive form

Question 38

What often needs to change shape in precursor enzymes for them to be activated

Answer 38

Active site

Question 39

How do precursor enzymes become activated

Answer 39

By the addition of a cofactor

Question 40

What is a precursor enzyme called before a cofactor is added

Answer 40

Apoenzyme

Question 41

What is a precursor enzyme called after a cofactor is added

Answer 41

Holoenzyme