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  • Enzymes
    • Biological catalysts
      • Speed up a reaction without being used up themselves
      • metabolic rate is the speed of all the reactions in the body added up.
        • sped up by enzymes
      • made of proteins
        • amino acids (similar to a chain) are conensed into a pacman like shape.
          • the 'mouth' of the pacman is called the active site.
            • the rest of the amino acids are used to produce thuis active site
            • the active site acts as a jigsaw piece in which a substrate can fit perfectly into it.
              • this reaction is also known as a lock and key hypothesis
              • this is an enzyme substrate complex
    • rate of reaction
      • Temperature
        • when a low temp the reaction not fast as the amount of kinetic energy is less therefore less movement which means there are less collisions.
        • when the temperature does initially increase the rate of reaction increases because there is more kinetic energy which means there are more frequent collisions.
        • when enzymes reach their optimum temperature they are at their peak conditions. this means they will complete reactions the quickest
        • when the temperature increases too much past the optimum temperature then the enzyme starts to denature meaning the structure of the active site unravels.
          • when the enzyme has denatured this means that the substrate can no longer fit in the active site which means overall there will be less frequent collisions.
      • pH
        • depending on where they are in the body.
    • to calculate the rat eof reaction just use 1 over the average time.


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