Enzymes

Question 1

What is an enzyme?

Answer 1

An enzyme is a globular protein which acts as a biological catalyst by speeding up the rate of a chemical reaction

Question 2

How are enzymes named?

Answer 2

Enzymes are typically named after the molecules they react with (called the substrate) and end with the suffix ‘-ase’

For example, lipids are broken down by the enzyme lipase

Question 3

What is the active site?

Answer 3

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

Question 4

What is the active site complementary to?

Answer 4

The active site and the substrate complement each other in terms of both shape and chemical properties

Question 5

Where do enzyme reactions typically occur?

Answer 5

Enzyme reactions typically occur in aqueous solution

Question 6

How do enzymes usually move around?

Answer 6

Sometimes an enzyme may be fixed in position (e.g. membrane-bound) – this serves to localise reactions to particular sites

Question 7

What does enzyme catalysis require?

Answer 7

Enzyme catalysis requires that the substrate be brought into close physical proximity with the active site

Question 8

What is formed when an enzyme and a catalyst collide?

Answer 8

When a substrate binds to the enzyme’s active site, an enzyme-substrate complex is formed

Question 9

What is formed once the reaction is catalysed?

Answer 9

The enzyme catalyses the conversion of the substrate into product, creating an enzyme-product complex

Question 10

What happens after the enzyme has catalysed the reaction?

Answer 10

The enzyme and product then dissociate – as the enzyme was not consumed, it can continue to catalyse further reactions

Question 11

How can the rate of enzyme catalysis be increased?

Answer 11

Increasing the molecular motion of the particles (thermal energy can be introduced to increase kinetic energy)

Increasing the concentration of particles (either substrate or enzyme concentrations)

Question 12

Can enzymes be denatured like proteins?

Answer 12

Yes

Like all proteins, enzyme structure can be modified by external factors such as high temperatures and extreme pH

Question 13

What happens when an enzyme is denatured?

Answer 13

These factors disrupt the chemical bonds which are necessary to maintain the tertiary structure of the enzyme

Question 14

What may factors affect in order to affect enzyme activity?

Answer 14

Various factors may affect the activity of enzymes, by either affecting the frequency of enzyme-substrate collisions or by affecting the capacity for the enzyme and substrate to interact (e.g. denaturation)

Question 15

What 3 factors can affect enzyme activity?

Answer 15

Temperature, pH and substrate concentration will all influence the rate of activity of an enzyme

Question 16

Why does increasing substrate concentration increase enzyme activity?

Answer 16

Increasing substrate concentration increases enzyme activity by providing more substrate molecules to bind to enzymes, leading to more enzyme-substrate complexes and faster reactions.

Question 17

Immobilized Enzymes

Answer 17

Enzymes that are trapped or attached to an inert material or support, making them easier to reuse and control in industrial processes. Immobilized enzymes are fixed in position, allowing substrate molecules to bind to the enzyme’s active site without the enzyme moving freely in solution.