Enzymes

• an enzyme is a biological catalyst that speeds up a chemical reaction
• enzymes are protein molecules and proteins are made up of amino acids
• enzymes don't get used up so they are re-useable and if they are used they don't change
• the rate of enzyme action is affected by

  • substrate concentration
  • temperature
  • PH
  • enzyme concentration
• all enzymes have a specific 3D shape called an active site which is complementary to the specific substrate. if an active site changes shape the enzyme will be denatured and no longer work
• digestive enzymes speed up digestion
• enzymes are found in salivary glands producing salivary amylase
• the pancreas produces pancreatic amylase
• the pancreas produces all enzymes
• a protein is one chain of amino acids and one amino acid is just an amino acid not a protein
• the part of an enzyme where the reaction occurs is known as the active site
• a substrate is the molecule that the enzyme works on.the substrate matches the shape of the enzyme. the mage is an example of an enzyme and an active site

  
• lipids-fats broken down by lipase into glycerol and fatty acids
• proteins-broken down by protease into amino acids
• carbohydrates-broken down by carbohydrase into glucose4
• starch-broken down by amylase into maltose
• enzymes work by the lock and key hypothesis/theory state that the active site must be complimentary to the substrate molecule
• bile emulsifies into smaller droplets to increase surface area for lipase to work on
• the enzyme amylase catalyses the breakdown of starch to maltose
• bile is alkaline meaning it neutralises stomach acids
• bile is produced by the liver and is stored in the gall bladder
• as acidic mush leaves the stomach acid enters the small intestine, the bile is released into the small intestine
• bile helps to break down fats
• protein digestion occurs in the stomach and small intestine
• food tests

  • starch is found by adding iodine and if it contains starch the colour change would be a blue/black colour
  • sugar is found by benedicts and will turn a green to a brick red colour change
  • protein is found by biuret and will turn a lilac/purple colour
  • fats are found by ethanol and will go to a cloudy white emulsion