Enzymes (Edexcel GCSE Chemistry: Combined Science)

• Enzymes are nature’s catalysts
• They are biological substances that catalyse reactions in living cells
• Enzymes are biological catalysts made from protein
• Enzymes speed up chemical reactions in cells, allowing reactions to occur at much faster speeds than they would without enzymes at relatively low temperatures (such as human body temperature)
• Important reactions that are biologically catalysed include respiration, photosynthesis and protein synthesis
• The production of alcohol by the fermentation of sugars occurs in the presence of a biological catalyst, yeast enzymes:

C₆H₁₂O₆ + enzymes → 2CO₂ + 2C₂H₅OH

• This reaction is very important to the production of alcoholic drinks such as beer and wine
• Not only do enzymes work at low temperatures, but they are very selective and will only work on very specific molecules when presented with a mixture of reactants

Enzymes are very selective which means they will work only on molecules which have exactly the right shape to fit into the active site of the enzyme