2.5 Enzymes

Question 1

What is the active site of an enzyme?

Answer 1

It’s a specific area on the enzyme where the catalytic reaction takes place, due to the tertiary or quaternary structure of the enzyme, allowing for enzyme-substrate specificity.

Question 2

What model explains how substrates bind to enzymes?

Answer 2

The induced fit model, which suggests the active site changes shape for a tighter fit when the substrate binds, facilitating the reaction.

Question 3

How do enzymes lower the activation energy of a reaction?

Answer 3

By providing an alternative pathway for the reaction that requires less energy, making it easier and quicker for the reaction to occur.

Question 4

What is enzyme catalysis dependent on?

Answer 4

Molecular motion and the collision of substrates with the enzyme’s active site in a specific alignment.

Question 5

What factors affect the rate of enzyme activity?

Answer 5

Temperature, pH, and substrate concentration.

Question 6

How does temperature affect enzyme activity?

Answer 6

Low temperatures slow down molecules, reducing collisions between enzymes and substrates. Optimal temperatures maximize activity, while temperatures too high can denature enzymes.

Question 7

What causes enzyme denaturation?

Answer 7

Extreme pH values, heat, and the presence of heavy metals, leading to irreversible changes in the enzyme’s structure.

Question 8

Can denaturation be reversible?

Answer 8

Yes, in cases of minor temperature increases or pH changes, the protein may refold to its original structure if not too severely altered.

Question 9

Why are immobilized enzymes used in industry?

Answer 9

To stabilize enzymes, allow for their reuse, and separate them from products, reducing production costs and avoiding contamination.

Question 10

What is an example of enzyme use in industry?

Answer 10

Production of lactose-free milk using lactase, which breaks down lactose into glucose and galactose.

Question 11

How does pH affect enzyme activity?

Answer 11

Each enzyme has an optimal pH. Deviation from this pH can reduce activity or denature the enzyme.

Question 12

What is a common method to study enzyme activity in a laboratory?

Answer 12

Designing experiments to test the effects of temperature, pH, and substrate concentration on enzyme activity, ensuring all other variables are controlled.

Question 13

What is the significance of enzymes being globular proteins?

Answer 13

This structure allows for the specific folding necessary to form the active site and for the enzyme to perform its catalytic function.

Question 14

Describe the graph showing the effect of temperature on enzyme activity.

Answer 14

The graph rises to a peak at the enzyme’s optimum temperature, indicating the highest rate of activity. Beyond this peak, activity sharply decreases due to enzyme denaturation.

Question 15

Explain the graph depicting the effect of pH on enzyme activity.

Answer 15

The graph forms a bell curve, peaking at the enzyme’s optimal pH, showing maximum activity. Activity decreases on either side of the peak as the pH deviates from the optimum, indicating denaturation or reduced efficiency.

Question 16

How does substrate concentration affect enzyme activity as shown in a graph?

Answer 16

Initially, the rate of reaction increases with substrate concentration due to more frequent collisions. However, it plateaus when all active sites are occupied, indicating that enzymes are saturated with substrate.

Question 17

How would you design an experiment to test the effect of pH on enzyme activity?

Answer 17

Set up several reactions with identical enzyme and substrate concentrations but vary the pH. Measure the rate of product formation using a spectrophotometer to assess how pH affects activity.

Question 18

What controls are important in an enzyme activity experiment?

Answer 18

Include a control where the enzyme is inactive (e.g., denatured by heat) to ensure that any observed reaction is enzyme-mediated. Keep all variables constant except the one being tested (temperature, pH, or substrate concentration).

Question 19

Describe the process and advantages of producing lactose-free milk.

Answer 19

Lactose-free milk is produced by adding lactase enzyme to break down lactose into glucose and galactose. Advantages include avoiding digestive issues for lactose-intolerant individuals, faster fermentation in yogurt production, and a sweeter taste.

Question 20

What are two methods of producing lactose-free milk?

Answer 20

Direct addition of lactase to milk, and passing milk over immobilised lactase on alginate beads, which prevents lactase from mixing with the milk.

Question 21

State uses of immobilised enzymes in industry.

Answer 21

Immobilised enzymes are used for producing biofuels, in pharmaceuticals for drug synthesis, in food processing like high-fructose corn syrup production, and in bioremediation to clean up pollutants.

Question 22

Why is immobilisation of enzymes advantageous in industry?

Answer 22

It allows enzymes to be reused, increases stability and efficiency, facilitates separation from reaction products, and can enhance the specificity and speed of reactions.