2. An enzyme is a biological catalyst that speeds up the rate of reactions in biological processes All enzymes are proteins, coded for by genes Enzymes are reaction-specific – each enzyme will only catalyse one type of reaction Enzymes can work inside cells but are also added to products like washing powder

3. enzyme active site substrate enzyme- substrate complex large substrate molecule broken into smaller molecules enzyme is unchanged

4. 1. They are all proteins 2. Each enzyme only catalyses one reaction 3. Enzymes can be reused 4. Temperature affects rate of enzyme reaction 5. pH affects rate of enzyme reaction Animation

5. Reaction rate Temperature Enzymes have a specific temperature range where the rate of reaction is the highest Reaction rate is slow at low temperatures Reaction rate increase as the temperature increases Reaction rate reaches its maximum at the optimum temperature At temperatures higher than optimum, the rate of reaction decreases as the enzyme denatures. Eventually, there will be no enzyme reactions.

6. Reaction rate pH Enzyme activity is also affected by pH. Some enzymes work best in neutral conditions, others in acidic or alkaline Optimum pH Enzyme denatured Animation