Factors affecting enzyme action

Question 1

For an enzyme to work, what must happen?

Answer 1

It must come into physical contact with its substrate and it must have an active site that fits the substrate.

Question 2

How can you measure enzyme-catalysed reactions?

Answer 2

Measure its time-course (how long it takes for a particular event to run its course), events being formation of the product or disappearance of the substrate.

Question 3

How do you calculate the rate of reaction at a certain point, using a graph?

Answer 3

Draw a tangent to the curve and calculate gradient of tangent.

Question 4

What is the effect of temperature on enzyme action?

Answer 4

• increases kinetic energy of molecules
• collide more rapidly and more often
• the enzyme and substrate come together more often in a given time.
• denaturing -permanent change to the tertiary structure as causes hydrogen and other bonds to break. Changes shape.

Question 5

How is rate of reaction expressed?

Answer 5

Per unit time.

Question 6

Why does pH effect enzyme reaction?

Answer 6

The pH of a solution is its hydrogen ion concentration.

• can alter charges of amino acids that make up the active site (the arrangement of the active site is partly determined by the groups -NH2 -COOH that make up the enzyme, the change in concentration of H ions affects this bonding.)
• it may cause the bonds maintaining the enzyme’s tertiary structure to break, the active site therefore changes shape.