1A - Factors affecting enzyme activity and enzyme-controlled reactions

Question 1

What are the 4 factors affecting enzyme activity?

Answer 1

Temperature
pH
Enzyme conc.
Substrate conc.

Question 2

What is most frequently measured when measuring enzyme-catalysed reactions?

Answer 2

The formation of products.

The disappearance of substrates.

Question 3

How do we measure the rate of change on a graph?

Answer 3

By measuring the gradient at the given point.

Question 4

What is the word to describe the enzyme and the substrates relationship with each other?

Answer 4

Complementary

Question 5

What does a rise in temperature increase?

Answer 5

The kinetic energy and therefore the number of successful and force of collisions.

Question 6

What does it mean if the temperature in an enzyme-catalysed reaction increases?

Answer 6

The enzyme and substrate molecules come together more often in a given time. There are more effective collisions resulting in more enzyme-substrate complexes being formed and so the rate of reaction increases.

Question 7

Explain the effect of temperature on enzyme activity:

Answer 7

More energy means more collisions between substrate and active site - collision theory.

Enzymes denature if temperature is too high and too many vibrations of particles begins to break bonds in protein structure.

Optimum temp in humans is 37 degrees.

Question 8

What is the optimum temperature for most enzyme activity in humans?

Answer 8

37 degrees celsius.

Question 9

What is the pH of a solution a measure of?

Answer 9

Measure of hydrogen ion concentration.

Question 10

What happens to the enzyme if pH is too low or too high?

Answer 10

The H+ and OH- ions interfere with the ionic and hydrogen bonds in an enzymes tertiary structure changing its shape. It becomes denatured and no longer works well.

Question 11

What is the optimum pH for most enzymes in the body?

Answer 11

pH7

Question 12

At what pH does pepsin work best?

Answer 12

pH2

Question 13

What is the general trend in how concentration of substrate/enzymes affect enzyme activity?

Answer 13

The higher the concentration, the greater the rate of reaction.

Question 14

Why is a linear trend of how concentration affects rate of reaction not right?

Answer 14

The graph plateaus as the substrate is used up.

Question 15

What do we measure to record the rate of reaction?

Answer 15

By measuring the change in the substrate or product over time.

Question 16

What are the 2 inhibitor molecules?

Answer 16

Competitive inhibitors and non-competitive inhibitors.

Question 17

What are enzyme inhibitors?

Answer 17

Substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity.

Question 18

What do competitive inhibitors do/how does competitive inhibition work?

Answer 18

When a molecule other than the enzyme’s specific substrate is complementary to the active site of the enzyme so it forms a complex with the enzyme’s active site so that it becomes occupied and the usual substrate cannot form the intended enzyme-substrate complex.

Question 19

What do non-competitive inhibitors do/how does non-competitive inhibition work?

Answer 19

They attach to the enzyme elsewhere and change its shape, distorting the shape of the active site so that it is no longer complementary to the substrate.