Enzymes (Cambridge (CIE) IGCSE Combined Science: Biology): Revision Note

What are enzymes?

• Enzymes are:

  • Proteins

  • Biological catalysts (biological because they are made in living cells, catalysts because they speed up the rate of chemical reactions without being changed)

  • Necessary to all living organisms as they maintain reaction speeds of all metabolic reactions (all the reactions that keep an organism alive)

How do enzymes work?: Extended

Enzyme substrate specificity

• Enzymes are specific to one particular substrate (molecule/s that get broken down or joined together in the reaction) as the enzyme is a complementary shape to the substrate

• The product is made from the substrate(s) and is released

Enzyme specificity: lock and key model of enzyme activity