Enzymes

PROTEINS, CATALYSTS AND ENZYMES

Protein molecules are made of long chains of amino acids.  The chains are folded to produce specific shapes.  The shape of a proteins depends on its function.  Proteins can be structural components of tissues eg muscle, hormones, antibodies or catalysts.

Chemical reactions in cells are controlled by a type of protein called enzymes.  Enzymes are biological catalysts - they speed up reactions.  Enzymes are large proteins and the shape of the enzyme is vital for its function.  This is because enzymes have a shape where other molecules can fit - known as the active site.  The substrate in a reaction can be held in the active site and either connected to another molecule or broken down.  Enzymes have many different abilities.  They can build large molecules from smaller molecules, change one molecule into another one or break down large molecules into smaller molecules.

FACTORS AFFECTING ENZYME ACTION

Enzyme reactions are similar to other reactions when the temperature is increased - an increase in temperature increases the rate of the reaction.  This is because the molecules move about more quickly and collide with other molecules with more energy.  However, if the temperature gets too hot the enzyme will become denatured and stop working.  This is because too high a temperature will change the shape of the active site.  Each enzyme works best at a particular pH value.  Some work best in acidic conditions, others work best in neutral or alkaline conditions.  If the the pH isn't right for the…