B3.4 Catalysts and Enzymes

Question 1

What is a catalyst?

Answer 1

A chemical which speeds up a chemical reaction, but isn’t used up in the reaction.

Question 2

What are enzymes?

Answer 2

Large protein molecules which are biological catalysts which speed up reactions. Each enzyme interacts with a particular substrate (reactant).

Question 3

Explain the lock and key theory.

Answer 3

Each enzyme has an active site, which is a unique shape which only it’s substrate will fit into.
When the substrate is in place in the active site, the rapid reaction takes place and the substrate is split into products.
They can also join small molecules together.

Question 4

What do the enzymes control?

Answer 4

The metabolism - the sum of all the reactions in a cell or in the body

Question 5

Give some examples of metabolic reactions that different enzymes can catalyse.

Answer 5

Building larger molecules from lots of smaller ones
Changing one molecule into another
Breaking down large molecules into smaller ones