Enzymes topic 2.5

Question 1

Catalysis

Answer 1

An enzyme is a globular protein which speeds up the rate of a chemical
equation by lowering the activation energy (i.e. it is a biological catalyst)
* Enzymes are not consumed by the reactions and can be re-used

Question 2

Lock and Key Model

Answer 2

• Enzyme and substrate complement each other precisely
  in terms of both their shape and chemical properties
• The active site and the substrate will share specificity

Question 3

Induced Fit Model

Answer 3

• Active site is not a rigid fit for the substrate and changes
  its conformation to better accommodate the substrate
• This stresses the substrate bonds and induces catalysis

Question 4

Factors Affecting Enzyme Activity

Answer 4

1. Temperature
2. pH
3. Substrate Concentration

Question 5

Temperature

Answer 5

• Increases enzyme activity (more kinetic energy = more collisions)
• Enzyme activity peaks at an optimal temperature
• Higher temperatures decrease activity (causes denaturation)

Question 6

pH

Answer 6

• Enzyme activity is highest at an optimal pH range
• Activity decreases outside of this range (due to denaturation)

Question 7

Substrate Concentration

Answer 7

• Increases enzyme activity (more particles = more collisions)
• At a certain point, activity plateaus (saturation of active sites)

Question 8

Enzyme Kinetics

Answer 8

The rate of enzyme catalysis can be increased by increasing
the frequency of enzyme-substrate collisions (molecular motion)
The rate of enzyme catalysis is decreased by denaturation

Question 9

Industrial Enzymes

Answer 9

Immobilised enzymes are often used in industrial practices
* They are fixed to a static surface to prevent enzyme loss
* This improves separation of product and purity of yield

Question 10

Application of immobilised enzymes

Answer 10

production of lactose-free milk and associated dairy products
* Lactase (enzyme) digests lactose into glucose / galactose
* Lactase is fixed to an inert surface (e.g. alginate beads)
* Milk is passed over this surface to become lactose free

Question 11

benefits associated with lactose free milk

Answer 11

• Provides a source of dairy for lactose-intolerant people
• Increases sweetness of milk (less need for sweeteners)
• Reduces crystallization and production times for cheese