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  • Enzymes
    • Proteins, catalysts and enzymes
      • protein molecules are made of long chains or amino acids
        • the shape of a protein depends on it's function
          • proteins can be: structural components of tissues (muscles etc), hormones, antibodies, catalysts
          • Their shape has an area where other molecules can fit- the 'active site'
            • The substrate in a reaction can be held in the 'active site' and can either be connected to another molecule or be broken down
      • chemical reactions are controlled by enzymes
        • enzymes are biological catalysts- they speed up reactions
          • enzymes can: build large molecules from many smaller molecules or change one molecule into another eg. all the digestive enzymes do this
    • Factors affecting enzyme action
      • reactions take place faster when it is warmer
        • at higher temp molecules move around quicker therefore collide more often
        • although if the temp is too high the enzyme will stop working (denatured) because the 'active site' changes shape
      • some enzymes work better depending on the pH value
        • some work best in acid conditions (stomach etc), whereas others need neutral or alkaline conditions
        • if the pH is too acidic or alkaline then the 'active site' could change shape (become denatured)
    • Enzymes in digestion
      • amylase (a carbohydrase)- produced by salivary glands, pancreas and small intestine. it catalyses the digestion of starch into sugars in the mouth and small intestine
        • amylase and lipase work best in slightly alkaline conditions
      • Protease- produced by the stomach, pancreas and small intestine. it catalyses the break down of proteins into amino acids in the stomach and small intestine
        • works best in acid conditions, glands in the stomach wall produce hydrochloric acid to create acidic condtions
      • Lipases- produced by pancreas and small intestine. catalyses the breakdown of lipids (fats and oils) to fatty acids and glycerol
        • amylase and lipase work best in slightly alkaline conditions
    • Making use of enzymes
      • biological detergents- contain protease and lipases that digest food stains (they work at low temps)
      • Baby foods- proteases are used to pre-digest proteins
      • Isomerase- used to convert glucose syrup into fructose syrup (stops foods being as fatty)
      • Carbohydrase- used to convert starch into sugar syrups for use in foods
      • In industry enzymes are used to bring about reactions at normal temp
    • High-tech enzymes
      • Advantages of using enzymes:
        • effective at removing stains
          • means biological washing powders can be used at low temps, reducing energy and cost
        • used in medicine to diagnose, control or even cure diseases
        • in industry it can reduce costs of energy and equipment
      • Disadvantages of using enzymes:
        • misusing washing powder could cause allergic reactions
        • could enter waterways via sewage system
        • industrial enzymes can be expensive to produce
        • Enzymes denature at high temps
        • some fabrics (wool) will be digested by proteases


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