BM: Factors Affecting Enzyme Action COPY

Question 1

What factors affect enzyme activity?

Answer 1

• Temperature
• pH
• Enzyme concentration
• Substrate concentration

Question 2

Draw a graph showing how temperature affects the rate of reaction:

Answer 2

Question 3

Draw a graph showing how pH affects enzyme action:

Answer 3

Question 4

Draw a diagram showing how enzyme concentration affects the rate of reaction:

Answer 4

Question 5

Describe the effect substrate concentration has on the rate of reaction:

Answer 5

• Higher concentration = faster reaction
• Saturation point is reached - active sites are ‘full’
• If no other variables are changed, rate will fall as substrate conc. decreases with time.

Question 6

Describe the effect temperature has on enzyme-controlled reactions

Answer 6

• As temperature increases, the kinetic energy increases. This allows more ES (enzyme-substrate) complexes to form.
• The rate of reaction increases up to the optimum temperature
• Once past optimum temp, bonds in the tertiary structure of the enzymes break - changing the stte of the active site

Question 7

Describe the effect pH has on enzyme-controlled reactions

Answer 7

• All enzymes have an optimum pH
• if the pH is below or exceeds the optimal pH, the H+ and OH- ions interfere with the ionic and hydrogen bonds in an enzymes tertiary structure.
• This changes its shape. It is denatured and no longer works

Question 8

Describe the effect enzyme concentration has on enzyme-controlled reactions

Answer 8

• increasing enzyme concentration will increase rate of reaction, as more enzymes will collide with substrates
• enzyme concentration only has effect up to a certain concentration because it is no longer a limiting factor

Question 9

What are the two types of inhibition?

Answer 9

Competitive and non-competitive

Question 10

Describe competitive inhibition:

Answer 10

• Inhibitor molecules have similar shape to substrate molecules.
• Compete with substrate molecules to bind to active site.
• No reaction occurs, but they block active site.

Question 11

What happens if there is a high concentration of inhibitor molecules relative to substrate molecules?

Answer 11

Inhibitor wil ltake up nearly all of active sites.

Question 12

Describe non-competitive inhibition:

Answer 12

• Inhibitor molecules bind to allosteric site.
• Active site changes shape so substrate can no longer bind to it.

Question 13

What happens if substrate concentration is increased during competitive inhibition?

Answer 13

Rate will increase as substrates have an increased chance of reaching active site before inhibitor.

Question 14

What happens if substrate concentration is increased during non- competitive inhibition?

Answer 14

Reaction rate will stay the same - enxyme activity will still be inhibited.