5. Enzymes

• Catalyst: a substance that increases the rate of a chemical reaction without being used up in the reaction
• Enzymes: biological catalyst (protein) that speeds up chemical reactions
• Why are enzyme important:

  • maintain reaction speed of all metabolic reactions
  • without enzymes it would take around 2-3 weeks to digest one meal
• Active site: the part of the enzyme where the substrate binds
• Substrate: a molecule that can bind with a specific active site to carry out a reaction
• Enzyme:

  A) substrate

  B) active site

  C) products

  D) enzyme-substrate complex

  
• Effect of changes in temperature on enzyme activity

  • optimum temperature - the perfect temperature that allows the highest enzyme activity to happen
  • denature - high temperature causes the active site to change shape not allowing the substrate to bind to it

  A) optimum temperature

  B) denatured

  
• Effect of pH level on enzyme activity

  • pepsin - an enzyme that works in the stomach: pH level = 2 (very acidic)
  • amylase - works in the mouth and small intestine: pH level = 7.5 (slightly basic)

  
• Enzyme: carbohydrates (amylase)

  • made where: salivary gland
  • function: breakdown of starch into sugar molecules
  • place secreted: mouth
• Enzyme: protease (pepsin, trypsin)

  • made where: gastric pits in stomach (protease), pancreas and stomach (pepsin, trypsin)
  • function: breakdown of protein into amino acids
  • place secreted: stomach
• Enzyme: lipase

  • made where: pancreas, lining of small intestine
  • function: breakdown of lipids into fatty acid and glycerol
  • place secreted: small intestine
• Bile: alkaline substance that is secreted into the small intestine

  • neutralises acid from stomach and create optimum conditions for enzymes
  • empulsify fats (breakdown food - physical)