5. Enzymes

Question 1

what are enzymes?

Answer 1

they are proteins with a tertiary structure, with a specific active site, which can bind to a complimentary substrate

Question 2

what is the role of enzymes?

Answer 2

molecules which speed up the rate of reaction by acting as catalysts,

Question 3

what complex do enzymes form?

Answer 3

enzyme-substrate complex

Question 4

how do enzymes speed up the process of an enzyme

Answer 4

lowering the activation energy required for a chemical reaction

Question 5

name the two enzyme models

Answer 5

1. Lock and Key model
2. Induced fit model

Question 6

outline the lock and key model

Answer 6

• original model
• active site is exactly specific and complimentary to substrate molecule
• substrate fits exactly when they collide forming an enzyme-complex substrate

Question 7

name the factors which affect enzyme action

Answer 7

1. enzyme concentration
2. substrate concentration
3. temperature

Question 8

why is enzyme concentration a factor affecting enzyme concentration

Answer 8

• increased enzyme concentration increases active site availability
• allows more enzyme substrate complexes to form
• rate of reaction increases as the substrate becomes the limiting factor
  (Linear then platueus graph)

Question 9

how does substrate concentration act as a factor affecting enzyme action

Answer 9

• more substrate molecules increases rate of reaction
• more collisions occur forming more enzyme-substrate complexes
• rate of reaction eventually slows as enzymes become a limiting factor
  (Slowly curves)

Question 10

how does temperature affect the enzyme action?

Answer 10

• temperature increases so does rate of reaction
• more kinetic energy
• more enzyme substrate complexes
• most effective at optimum temperature
• at high temperatures denaturation occurs, breaking H bonds and changing shape of tertiary structure and therefore active site
• stopping complex formation
  (Bell shaped curve)

Question 11

define enzyme inhibitors

Answer 11

enzyme activity being slowed or prevented by other molecules that are not substrates

Question 12

name two types of inhibitors

Answer 12

1. competitive inhibition
2. non-competitive inhibition

Question 13

outline competitive inhibition

Answer 13

• similar shape to substrate
• compete with substrate
• bind to active site
• prevents enzyme-substrate complexes being formed
• increasing concentration of substrate will reverse the effects of a competitive inhibitor
  (higher line on graph than non-competitive)

Question 14

outline non-competitive inhibitors

Answer 14

• bind away from the active site
• binds to the allosteric site
• causes tertiary shape to changes
• affects the complimentary active site
• no enzyme-substrate complexes can be formed
• increasing concentration of substrate will have no effect