2.5 Enzymes

Question 1

What is an enzyme?

Answer 1

A globular protein that acts as biological catalyst by speeding up the rate of a chemical reaction

Question 2

What happens to enzymes when they catalyse a reaction?

Answer 2

They are not changed or consumed by the reaction

Question 3

Can enzymes be reused?

Answer 3

Yes

Question 4

What are enzymes typically named after?

Answer 4

The molecules they react with

Question 5

What is the active site?

Answer 5

The region on the surface of the enzyme which binds to the substrate molecule

Question 6

What are the two ways the active site and substrate complement each other?

Answer 6

Shape and chemical properties

Question 7

What is capable of binding to a particular enzymes active site?

Answer 7

A specific substrate

Question 8

Where do enzyme reactions typically take place?

Answer 8

In aqueous solution

Question 9

What does the fact that enzyme reactions take place in aqueous solutions show about its position?

Answer 9

The substrate and the enzyme are randomly moving within the solution

Question 10

What does an enzyme being in a fixed position do?

Answer 10

Serves to localise reactions to particular sites

Question 11

What does enzyme catalysis need?

Answer 11

The substrate to be in close proximity with the active site

Question 12

When is an enzyme-substrate complex formed?

Answer 12

When a substrate binds to the enzymes active site

Question 13

How is an enzyme product complex created?

Answer 13

When the enzyme catalyses the conversion of the substrate into product

Question 14

What happens after the enzyme product complex is created?

Answer 14

The enzyme and product dissociate

Question 15

How can you increase the rate of enzyme catalysis?

Answer 15

By increasing the frequency of collisions

Question 16

How can you increase the rate of collisions?

Answer 16

Increasing the molecular motion of the particles
Increasing the concentration of the particles

Question 17

What are the shape and chemical properties of an active site dependent on?

Answer 17

The tertiary structure of the enzyme

Question 18

What can cause an enzyme structure to be modified?

Answer 18

External factors like temperature and pH

Question 19

How does temperature and pH affect enzymes?

Answer 19

They disrupt the chemical bonds which maintains the structure of the enzyme causing denaturation

Question 20

What will a change to the structure of the active site do?

Answer 20

Negatively affect the enzymes capacity to bind to the substrate

Question 21

What affects the rate of activity of an enzyme?

Answer 21

Temperature
pH
Substrate concentration

Question 22

What does low temperature during a reaction result in?

Answer 22

Insufficient thermal energy for the enzyme catalysed reaction to happen

Question 23

What does increasing the temperature do during a reaction?

Answer 23

Increases the speed and motion of both enzyme and substrate

Question 24

Why does an increase in temperature result in higher enzyme activity?

Answer 24

Because a higher kinetic energy results in more collisions between the enzyme and the substrate

Question 25

What happens at an optimal temperature?

Answer 25

The rate of enzyme activity will be at its peak

Question 26

In terms of temperature what causes an enzyme stability to decrease and why?

Answer 26

Higher temperatures as the thermal energy disrupts the enzymes hydrogen bonds

Question 27

What does changing the pH do to the enzyme?

Answer 27

Alter the charge of the enzyme and thus its solubility an overall shape

Question 28

What does changing the shape or the charge of the active site do?

Answer 28

Stop its ability to bind to the substrate

Question 29

What does moving out of an enzymes optimal pH do?

Answer 29

Stop its enzyme activity

Question 30

What does increasing the substrate concentration do?

Answer 30

Increase the activity of a corresponding enzyme

Question 31

What does having more substrates mean?

Answer 31

There is an increased chance of enzyme and substrate colliding and reacting in a given period

Question 32

When talking about substrate concentration, what happens after a certain point?

Answer 32

The rate of activity will stop regardless of substrate levels because all enzymes will be bound and reacting

Question 33

What is the shape of rate of reaction against temperature graph?

Answer 33

Slow gradient and steep decrease

Question 34

What is the shape of rate of reaction against pH graph?

Answer 34

Equal rise to peak as downhill from peak

Question 35

What is the shape of rate of reaction against substrate concentration graph?

Answer 35

Sharp increase then it plateaus

Question 36

When designing an experiment to test the effect of factors affecting enzyme activity, what are the three key decisions?

Answer 36

Which factor to investigate? Which enzyme/substrate reaction to use? How to measure the enzyme activity?

Question 37

When designing an experiment to test the effect of factors affecting enzyme activity, what are your choice of independent variables?

Answer 37

Temperature pH substrate concentration Presence of inhibitor

Question 38

When designing an experiment to test the effect of factors affecting enzyme activity, what are the two ways reactions are measured in accordance to?

Answer 38

The amount/rate of substrate decomposition or product formation

Question 39

What are immobilised enzymes used for?

Answer 39

To be fixed to a static surface in order to improve the efficiency of the catalysed reaction

Question 40

Why is separation of the product more easily achieved?

Answer 40

The enzyme remains attached to the static surface

Question 41

How are enzymes used in biofuels?

Answer 41

To breakdown carbohydrates to produce ethanol-based fuels

Question 42

How are enzymes used in medicine?

Answer 42

To identify a range of conditions like pregnancy or certain diseases

Question 43

How are enzymes used in biotechnology?

Answer 43

In multiple processes like gene splicing

Question 44

How are enzymes used in food production?

Answer 44

In the production and refinement of beers and dairy products

Question 45

How are enzymes used in textiles?

Answer 45

In the processing of fibres

Question 46

How are enzymes used in paper?

Answer 46

Assisting the pulping of wood for paper production

Question 47

What is lactose?

Answer 47

A disaccharide of glucose and galactose

Question 48

What can break down lactose?

Answer 48

Lactase

Question 49

Where is lactose intolerance particularly high?

Answer 49

In asian, african and aboriginal populations

Question 50

Why is lactose intolerance lower in europeans?

Answer 50

A mutation that maintains lactase production into adulthood

Question 51

When do mammals show a decrease in lactase production?

Answer 51

After weaning

Question 52

How can lactose free milk be produced?

Answer 52

By treating the milk with lactase

Question 53

What is the process of using lactase for lactose free milk?

Answer 53

The lactase is purified by yeast or bacteria and then bound to an inert substance. the milk is then passed through this repeatedly

Question 54

How are scientists trying to create a cow that produces lactose free milk?

Answer 54

By splicing the lactase gene in the cows genome so lactose is broken down before milking

Question 55

What are the four advantages of lactose free milk?

Answer 55

It is a source of dairy for lactose free individuals Ir is a means of increasing sweetness without artificial sweetners A way of reducing crystillisation of ice cream Reduces production time for cheeses and yogurts