B1.2.4 - Enzyme Reactions

Question 1

What factors affect enzymes?

Answer 1

The rate of an enzyme-catalysed reaction depends on a number of factors, including temperature and pH. It is also affected by three concentrations of the enzyme and substrate

Question 2

How does temperature affect enzyme-controlled reactions?

Answer 2

At higher temperatures the enzyme and substrate molecules move faster and collide move often. In general, the higher the temperature, the faster the reaction.

Question 3

What happens if the temperature becomes too high?

Answer 3

The amino acid chains in the protein start to unravel, changing the shape of the active site. The enzyme is now denatured. The substrate can no longer bind and so the rate of the reaction decreases. Most denatured enzymes cannot return to their original shape - it is an irreversible change

Question 4

How does pH affect enzyme-controlled reactions?

Answer 4

Each enzyme has its optimum pH. A change in pH affect the interaction between amino acids in a chain. This may make the enzyme unfold, changing the shape of the active site. The enzyme is denatured

Question 5

What other factors affect enzyme-controlled reactions?

Answer 5

In general, the higher the substrate concentration is, the faster the rate of reaction. But at a certain substrate concentration, all the enzyme molecules are bound to substrate molecules. The rate of reaction is at its maximum. Any increase would not increase it as there are no more enzymes.

The same goes for enzyme concentration, but this is limited by substrate concentration