enzymes

• what do enzymes do?

  enzymes catalyse (speed up) chemical reactions
• what are enzymes?

  enzymes are large protein molecules and they have a groove on their surface called the active site
• what is the active site?

  the active site is where the substrate attaches to
• what is the substrate?

  molecule that the enzyme breaks down
• the substrate fits perfectly into the active site
• enzymes are specific, the substrate must fit perfectly into the active site
• what enzymes are proteins broken down by?

  proteases which are found in the stomach, small intestine and pancreas
• what are proteins?

  long chains of chemicals called amino acids
• what happens when we digest proteins?

  the protease enzymes convert the protein back to the individual amino acids which are then absorbed into the bloodstream
• what happens when the amino acids are absorbed by the body cells?

  they are joined together in a different order to make human proteins
• what does starch consist of?

  a chain of glucose molecules
• what enzymes are carbohydrates broken down by?

  carbohyrdases, amylase is a carbohydrase which breaks down starch
• what is produced when carbohydrates like starch are digested?

  we produce simple sugars
• where is amylase found in?

  • the saliva
  • the pancreatic fluid
• what does a lipid molecule consist of?

  • fatty acids
  • glycerol
• what enzymes are lipid molecules digested by?

  lipase, this produces glycerol and fatty acids
• where do we find lipase?

  • in the pancreatic fluid
  • in the small intestine
• where is bile made in?

  the liver
• where is bile stored?

  in the gall bladder
• bile converts large lipid droplets into smaller droplets
• bile emulsifies the lipid, this massively increases the surface area of the lipid droplets and increases the rate of lipid breakdown by lipase
• what does bile being alkaline allow it to do?

  neutralise stomach acid, creating alkaline conditions in the small intestine. this inrceases the rate of lipid digestion by lipase
• what happens to enzyme activity as we increase the temperature?

  the activity of the enzyme increases (the reaction gets faster)
• as the temperature increases, the enzyme and substrate are moving faster so there are more collisions per second between the substrate and the active site
• what happens at optimum temperature?

  there is maximum frequency of successful collisions between the substrate and the active site
• what happens at high temperatures to the enzyme molecule?

  the enzyme molecule vibrates and the shape of the active site changes
• what do we call it when the substrate no longer fits into the active site?

  denatured which means that the enzyme can no longer catalyse the reaction
• the active site denatures if the conditions are too acidic or too alkaline (ph)