Enzymes and Digestion

Cards (42)

  • enzymes are proteins which act as biological catalysts and speed up chemical reactions, which take place in living cells, without being used up or changed themselves
  • enzyme + substrate -> enzyme/substrate complex -> enzyme + products
  • extracellular enzymes do their job outside the cell it's made
  • intracellular enzymes work inside the cell they were produced by
  • enzymes control the rate of all chemical reactions in the body
  • enzymes have a specific shape that is complementary to the substrate
  • catalase is an intracellular enzyme that breaks down the toxic substance hydrogen peroxide, which is produced by many chemical reactions within cells
  • hydrogen peroxide -catalase-> water + oxygen
  • digestive enzymes are extracellular which are released into various areas of the alimentary canal (small intestine/ mouth)
  • starch -amylase-> sugar/glucose
  • proteins -protease-> amino acids
  • lipids -lipase-> glycerol and fatty acids
  • substrate-specificity means that different enzymes can only break down one type of molecule
  • the active site is where the substrate binds to the enzyme
  • the active site has a lock and key fit with the substrate
  • amylase is from saliva from salivary glands, pancreatic juice and intestinal juice, found in the mouth, small intestine and pancreas
  • protease is from gastric juice, pancreatic juice and intestinal juice, is found in stomach, small intestine and pancreas
  • lipase if from pancreatic juice and intestinal juice, found in the small intestine and pancreas
  • enzymes are not used up or altered by the reaction although they can run down and have to be replaced
  • enzymes are affected by changes in temperature and pH
  • as temperature increases, the kinetic energy increases and this causes more collisions between the enzyme and substrate so rate of reaction increases
  • the temperature which gives the highest rate of reaction is called the optimum temperature
  • when the temperature is increased too much the enzyme becomes denatured, meaning the shape of the active site has changed
  • when an enzyme is denatured by temperature the effect is irreversible
  • each enzyme has an optimum pH, the pH that it works best in
  • when an enzyme is denatured by pH level it is reversable
  • as the enzyme concentration is increased, so does the rate of reaction - is directly proportional
  • there are more active sites available to bind witha substrate molecule at any one time
  • substrates have to wait for an active site to become available and the more enzymes the less time the substrate will have to wait
  • an enzyme inhibitor is a substance that interferes with enzyme action, reducing enzyme activity, competitive inhibitors black the active site so no substance can bind
  • the gut wall acts like a net that lets small soluble molecules through but stops large molecules
  • enzymes are used in digestion to break down large insoluble food molecules into small soluble ones in your gut so that they can be absorbed into the blood
  • biological washing powders contain enzymes as well as detergents, stains in clothes include protein (blood and egg) and lipid stains (grease) so there is protease and lipase to break down the molecules so they dissolve in water and can be washed away, they are also thermostable meaning they can be effective at different temperatures
  • digestion is the break down of large molecules into smaller ones so that they can be absorbed from the gut and into the blood
  • digestion is a series of chemical reactions and is carried out by enzymes and the products of those reactions are absorbed in the ileum
  • the ileum is the second part of the small intestine, it is involved in the absorption of the digested food through the gut wall and into the blood
  • ileum has a large surface area because of it is long, in folds and has thousands of tiny finger-like structures called villi
  • villi have a good blood supply - each villus has its own capillary network
  • each villus only has a single layer of cells on its surface meaning the absorbed food has a short distance to travel before it is absorbed into the blood
  • ileum has thin, permeable membranes