2.5 ENZYMES

Question 1

Enzymes

Answer 1

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

they are not change or consumed - they can be reused

Question 2

Active site

Answer 2

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

Question 3

Enzyme catalysis

Answer 3

1. When a substrate binds to the enzyme’s active site, an enzyme-substrate complex is formed
2. The enzyme catalyses the conversion of the substrate into product, creating an enzyme-product complex
3. The enzyme and product then dissociate – as the enzyme was not consumed, it can continue to catalyse further reactions

Question 4

Collision Frequency

Answer 4

1. Increasing the molecular motion of the particles (thermal energy can be introduced to increase kinetic energy)
2. Increasing the concentration of particles (either substrate or enzyme concentrations)

Question 5

Enzyme Immobilisation

Answer 5

Enzymes are attached to a material to restrict their movement

1. Aggregations of enzymes bonded together
2. Attached to surfaces eg: glass
3. Entrapped in gels eg: alginate gel beads

Question 6

Advantages of enzyme immobilisation

Answer 6

1. Concentration of substrate can be increased
2. Recycled enzymes can be used many times, immobilised enzymes are easy to separate from the ration mixture → cost saving
3. Separation of the products is straight forward → reaction can stop at the correct time
4. Stability of the enzyme to changes in temperature and pH is increased reducing the rate of degradation → cost saving

Question 7

Immobilising lactase in the production of lactose free milk

Answer 7

Lactase obtained from yeast or bacteria

Lactase is bound to the surface of alginate beads

Milk is passed over the beads

Immobilised enzymes remains to be used again and does not affect the quality of lactose free milk