2 main types of enzymes Catabolic enzymes which (break down) large molecules into smaller molecules e.g. digestion of starch by the enzyme amylase into glucose. Anabolic enzymes which (build up) small molecules to form larger molecules e.g. production of glucose during photosynthesis from carbon dioxide, water and light.

Structure of an Enzyme Molecule Enzymes are proteins made up on long chains of amino acids. These long chains fold to produce a special shape which is vital for the enzyme‘s function. Active Site

Lock and Key Model of Enzyme Action

Step-by-step Shape of the enzyme’s active site is complimentary to the shape of one particular substrate. The two bind together to form an enzyme-substrate complex. The reaction between them take place rapidly. The products are released from the enzyme’s active site, and the enzyme may be reused.

Summary What Enzymes Are and What They Do Protein molecules (made up of amino acids) Biological catalysts (Increase the speed of chemical reactions) Specific (Each one catalyses one particular reaction) Reusable (Can be used again and again) Affected by temperature and pH. Found in animals, plants and microorganisms.

Enzymes in Digestion Enzymes break down large insoluble food molecules into smaller, soluble ones which can be absorbed through the small intestine wall to enter the bloodstream. Different parts of the digestive tract have different pH conditions to enable different enzymes to work.

The Main Groups of Digestive Enzymes Lipase enzymes digest fatty substrates. Protease enzymes digest protein substrates. Carbohydrase enzymes digest carbohydrate substrates.

Substrate Enzyme Product Where enzyme produced Optimum pH Starch Amylase (a carbohydrase) Glucose Salivary glands & pancreas pH7 Protein Trypsin (a protease) Amino acids Stomach, pancreas, & small intestine pH3 Lipids Lipases (fats) Fatty acids & glycerol Pancreas pH8

The Action of Bile It’s produced by the liver and is stored in the gall bladder which, squirts it into the small intestine. It’s alkaline to neutralize acidic chyme coming from stomach. It emulsifies fats to break them into smaller droplets which increases the surface area for lipase enzymes to work.