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Question 1

What is an active site?

Answer 1

A small pocket within an enzyme where the substrate of the enzyme fits at the start of a reaction.

Question 2

Why can’t substrates fit in all active sites?

Answer 2

Different substrates have different 3D shapes, and different enzymes have active sites of different shapes. This explains why active sites can only work with specific substrates that fit the active site.

Question 3

How is a product molecule made? (3 steps)

Answer 3

1. Two different substrate molecules go into the active site of an enzyme.
2. The active site holds the substrate molecules tightly in the right position for bonds to form and make a product molecule.
3. The product molecule is a slightly different shape to the substrate molecules, so it no longer fits tightly in the active site and is released.

To separate a product molecule, it is the same process but the opposite order.

Check Biology page 19.

Question 4

How does an enzyme become denatured?

Answer 4

Changes in pH or temperature can affect how the protein folds up, affecting the shape of the active site. This causes the substrate to no longer fit neatly into the active site and the enzyme no longer catalysing the reaction.

Question 5

How does temperature affect an enzyme’s performance positively?

Answer 5

As temperature increases, molecules move faster. Higher speeds increase the chance of substrate molecules bumping into enzyme molecules and slotting into the active site.

Question 6

How does temperature affect an enzyme’s performance negatively?

Answer 6

When the temperature gets too high, the shapes of the enzyme molecule starts to change. The higher the temperature, the more the change. This makes it more difficult for the substrate molecule to fit into the active site.

Question 7

What is the temperature or pH that an enzyme works the best at called?

Answer 7

Optimum temperature or optimum pH.