3.1.4.2 Enzymes

Question 1

What is the role of enzymes

Answer 1

Increase the rate of reaction but are not consumed by the process
Catalyse ALL reactions in organisms

Question 2

Where do enzymes work and how are they specific

Answer 2

Inside and outside cells
Specific = different enzyme for each reaction

Question 3

What type of protein are enzymes

Answer 3

Globular

Question 4

How does the substrate bind to the active site

Answer 4

• Tertiary structure specific and (nearly) complimentary to substrates
• Substrates bind at the active site

Question 5

What does the enzyme do the energy in the reaction and why is this important

Answer 5

• Reduce the activation energy of the reaction
• This energy is required to break bonds and start a reaction

Question 6

How do enzymes work - induced fit model

Answer 6

• S. collides with the enzymes A.S and bind - ESC
• formation of IMF between A.C and S. causes enzymes A.C to change shape slightly
• A.C becomes complimentary with S.
• strains bond in S.
• lowers a.energy of reaction

Question 7

How does temperature affect the rate of enzyme controlled reactions

Answer 7

• Increasing temp increases rate
• increasing K.E
• more successful E.S collisions
• above optimum temp, rate decreases, cas enzyme denatures
• HYDROGEN BONDS disrupted
• Tertiary structure deforms
• A.S changed shape & no longer complimentary to S.

Question 8

PH “”

Answer 8

• changes in PH away from optimum causes rate to decrease
• IONIC FORCES (&hydrogen bonds) disrupted
• tertiary structure deforms
• A.S changes shape & no longer complimentary to S.

Question 9

Substrate (S.) concentration

Answer 9

• increasing enzyme conc increases rate
• more E.S collisions
• max rate when all S. reacts instantly

Question 10

Inhibitors: what does a competitive inhibitor do

Answer 10

• inhibitor is a similar shape to the active site
• inhibitor binds to A.S, blocking it
• substrate cannot bind

Question 11

How can you reduce the effect if a competitive inhibitor

Answer 11

Increase the substrate concentration

Question 12

What does a non-competitive inhibitor do

Answer 12

• binds to a different site on the enzyme
• causes change in tertiary structure so A.S changes shape
• A.S no longer complimentary to S.
• reduces maximum possible rate of reaction

Question 13

How to calculate rate of reaction

Answer 13

• rate = change / time
• ROR slows as reaction proceeds:
  Substrate concentration falls
• use tangent to calculate rate at a specific time
• initial rate = rate at start of reaction
  Steepest gradient = fastest reaction