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

Enzymes are:

• catalysts that speed up the rate of a chemical reaction without being changed or used up in the reaction

• 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) at a rate that can sustain life

  • Without digestive enzymes, one meal would take around 2–3 weeks to digest; with enzymes it takes 3-4 hours

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