Digestive Enzymes

• Enzymes catalyse chemical reactions
• Enzymes are large protein molecules with a 'groove' on their surface called the active site
• The active site is where the substrate attaches to
• The substrate is the molecule that the enzyme breaks down
• The substrate fits perfectly into the active site of the enzyme, which then breaks down the substrate into the products
• Proteins are broken down by enzymes called proteases which are broken down into amino acids
• Lipases break down lipids (fats) producing glycerol and fatty acids.
• Carbohydrases break down carbohydrates to simple sugars. Amylase is a carbohydrase which breaks down starch.
• When we digest proteins, the protease enzymes convert the protein back to the individual amino acids, which are then absorbed into the bloodstream. When the amino acids are absorbed by the body cells, they are joined together in a different order to make human proteins
• Starch consists of a chain of glucose molecules. It is broken down by the enzyme amylase. When starch is digested, simple sugars are produced.
• Amylase is found in the saliva and pancreatic fluid
• We find lipase in the pancreatic fluid and also in the small intestine
• Bile is made in the liver and stored in the gall bladder, helping to speed up the digestion of lipids but is not an enzyme. Bile 'emulsifies' lipids, breaking them into smaller droplets so they can be absorbed more easily.
• Bile is alkaline, allowing it to neutralise stomach acids and creating alkaline conditions within the small intestine, increasing the rate of lipid digestion by lipase.