Enzymes

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  • Enzymes
    • Chemical reactions are controlled by proteins called enzymes.
      • Proteins
    • Enzymes are biological catalysts.
    • Enzymes can: 1.Build large molecules from smaller ones. 2.Change one molecule to another one. 3.Break down large molecules into smaller ones.
    • Enzymes in digestion
      • Amylase
        • Produced by the salivary glands, pancreas and small intestine.
        • Amylase catalyses the digestion of starch into sugars in the mouth and small intestine.
      • Lipase
        • Produced by the pancreas and small intestine.
        • Lipase catalyses the breakdown of lipids into fatty acids and glycerol.
      • Protease
        • Produced by the stomach, small intestine and pancreas.
        • Protease catalyses the breakdown of proteins into amino acids in the stomach and small intestine.
        • Protease works best in acidic conditions in the stomach.
          • Glands in the stomach wall produce hydracloric acid to create these conditions.
      • Speeding up digestion
        • Protease works best in acidic conditions in the stomach.
          • Glands in the stomach wall produce hydracloric acid to create these conditions.
        • Amylase and lipase work best in the small intestine where conditions are more alkaline.
          • Amylase
            • Produced by the salivary glands, pancreas and small intestine.
            • Amylase catalyses the digestion of starch into sugars in the mouth and small intestine.
          • Lipase
            • Produced by the pancreas and small intestine.
            • Lipase catalyses the breakdown of lipids into fatty acids and glycerol.
        • The liver produces bile which is stored in the gall bladder.
          • The alkaline bile is squirted into the small intestine and neutralises the stomach acid.
    • Factors affecting enzymes
      • Reactions are faster when the temperature increases.
        • At higher temperatures the molecules move around quicker and so collide with each other more often.
        • If the temp gets too hot then the enzyme denatures; meaning that the active site has changed shape.
      • Each enzyme works best with a particular pH value.
        • If the pH is too acidic or alkaline then the active site will change therefore the enzyme will denature.
    • Use of enzymes
      • Biological detergents contain proteases and lipases that digest food and also work at lower temperatures.
      • Proteases are used to pre-digest proteins in some baby foods.
      • In industry, enzymes are used to bring out reactions at normal temperatures and pressures. Traditional reaction use expensive equipment to get high temps and pressures.
  • Protein molecules are made up of long chains of amino acids.
    • The long chains are folded to produce specific shapes
      • The shape of a protein depends on its function.
        • Proteins can be:   1.Catalysts 2.Antibodies 3.Hormones 4.Structural components of tissues
    • Proteins
  • Factors affecting enzymes
    • Reactions are faster when the temperature increases.
      • At higher temperatures the molecules move around quicker and so collide with each other more often.
      • If the temp gets too hot then the enzyme denatures; meaning that the active site has changed shape.
    • Each enzyme works best with a particular pH value.
      • If the pH is too acidic or alkaline then the active site will change therefore the enzyme will denature.

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