Enzymes

• Enzymes catalyse (speed up) chemical reactions
• Enzymes are large protein molecules and thay have a groove on their surface called rhe active site
• The active site is where the substrate attaches to
• the substrate fites perfectly into the active site

  
• The enzyme now breaks down the substrate into the products

  
• This substrate does not fit into the active site. The enzymes cannot break down this subsrate

  
• Ensymes are specific. The substrate must fit perfectly into the active site (the lock and key theory)
• Proteins are broke down by enzymes called proteases

  
• Proteins are long chains of chemical called amino acids

  
• 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

  
• Carbohydrates are broken down by enzymes called carbohydrases. In the case of starch this is called amylase.
• When carbohydrates like starch are digested, we produce simple sugars.

  
• Amylase is found in the saliva and pancreatic fluid
• A lipid molecule consists of a molecule of glycerole attached to 3 molecule of fatty acids

  
• Lipid molecules are digested by the enzyme lipase. This produces glycerol and fatty acids.

  
• Bile is made in the liver and it is stord in the gall bladder

  
• bile helps to speed up the digestion of lipeds but bile is not an enzyme
• Bile converts large lipid droplets into smaller droplets

  Bile emulsifies the lipid

  this massibley increses the surface area of the liped droplets

  this increses the rate of lipid breakdown by lipase

  
• Bile is also alkaline. this allows it to nutralise stomach acid, creating alkaline conditions in the small intestine.