BM : enzymes

Question 1

What is an enzyme

Answer 1

a biological catalyst

Question 2

What does an enzyme do?

Answer 2

Speeds up the rate of reaction without being used up

- lowers activation energy

Question 3

What makes an enzyme specific

Answer 3

• has a specific active site

- only complementary substrate can bind to the active site to form an enzyme substrate complex

Question 4

What is lock and key model

Answer 4

• active site shape is rigid

- only exact complementary substrate can bind to form ES complexes

Question 5

What is induced fit model?

Answer 5

Active site changes shape, substrate binds to active site

- the active site changes shape so the substrate fits exactly forming an ES complex

Question 6

Affect of substrate concentration on enzyme activity

Answer 6

• increase substrate concentration
• increases chance of successful collisions
• increases chance of forming an ES complex
• increases rate of reaction
• this continues until a;l enzymes actives sites are full/ saturated = maximum reaction

Question 7

Affect of enzyme concentration on enzyme activity

Answer 7

• increased enzyme concentration
• increases chances of successful collisions
• increases the chance of forming ES complexes
• increases rate of reaction
• continues until all substrates are used up = maximum rate of reaction

Question 8

Affect of temp on enzyme activity leading to optimum

Answer 8

• as temp increases
• kinetic energy increases
• molecules move faster
• increases chance of successful collisions
• increases chance of forming ES complexes
• increases rate of reaction
• carries on till optimum

Question 9

Affect of temp on enzyme activity after optimum

Answer 9

• bonds in tertiary structure break (hydrogen + ionic bonds)
• lose active site shape
• substrate no longer complementary
• cant form ES complexes
• enzyme denatured

Question 10

Affect of pH on enzyme activity

Answer 10

• if pH changes away from optimum
• bonds in tertiary structure break
• lose active site shape
• no longer form ES complex
• enzyme denatured

Question 11

What are competitive inhibitors

Answer 11

a substance with a similar shape to the substrate and complementary shape to the enzymes active site

• binds to the active site
• blocking it
• preventing ES complexes forming

Question 12

What are non-competitive Inhibitors

Answer 12

a substance that binds to the other site on the enzymes other than the active site

• causes the active site to change shape
• so less ES complexes are formed