ATS GCSE Biology - Digestive enzymes Key words

• enzymes

  catalyse specific reactions in living organisms due to the shape of their active site

  
• lock and key theory


  as a simplified model to explain enzyme action relating to the specific shape of the active site

  
• amylase production

  salivary glandspancreassmall intestine

  
• amylase site of action

  mouthsmall intestine

  
• protease production


  stomachpancreassmall intestine

  
• protease site of action

  stomachsmall intestine

  
• lipase production


  pancreassmall intestine

  
• lipase site of action

  small intestine

  
• carbohydrases

  break down carbohydrates to simple sugars amylase is a carbohydrase

  
• amylase


  breaks starch into maltosemaltose can then be broken into glucose

  
• maltose


  two glucose molecules joined together

  
• proteases


  break down proteins to amino acids

  
• lipases


  break down lipids into glycerol and fatty acids

  
• products of digestion


  are used to build new carbohydrates, lipids and proteinssome glucose is used in respiration

  
• temperature


  affects the rate at which chemical reactions take place

  
• low temperatures


  slows reactions down

  
• optimum temperature


  enzymes are working at their fastest rate for that temperature

  
• too hot

  enzymes denature

  
• denatured


  active site changes shape and no longer fits the substrate

  
• fever


  can be dangerous when ill as enzymes start to denature at 41 degrees Celsius

  
• bacteria


  living in hot springs survive at temperatures upto 80 degrees Celsius and higherother species living in very cold deep seas have optimum temperatures at O degrees Celsius and below

  
• optimum pH


  the pH conditions where enzymes work fastest

  
• protease pH


  pepsin and trypsin have different optimum pH

  
• pepsin

  protease made by the stomachacidic optimum pH

  
• trypsin


  pancreas and small intestine protease optimum pH around 7.5

  
• different enzymes

  catalyse specific types of metabolic reactions

  
• metabolic reactions

  building larger molecules from lots of smaller oneschanging one molecule into anotherbreaking down large molecules into smaller ones

  
• catalyse


  speed up