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  • Biology Unit 3
    • DNA
      • Its structure was discovered by Watson and Crick in 1953.
        • It is important to know the structure as it is easier to understand other things
      • Found inside the nuclues.
        • Can replicate itself by uncoiling itself, unzipping, join with other nucleotides and winding back up.
      • Made up of 4 bases. A, T. C, G.
      • it is important as it codes for everything in our body
        • a sequence of three bases code for the production of a certian amino acid.
          • these combine to make protiens
      • A mutation can happen when the DNA base sequence is altered
      • The change in the DNA causes the wrong proteins to be produced meaning the wrong proteins are made
    • Enzymes
      • Biological catalysts which speed up reaction in the body.
      • the active site is the part where it joins to its substrate
        • If it is damaged then the enzyme wont be able to catalyse the reaction.
          • it has been denatured
        • This is called the 'lock and key' mechanisim
    • Blood
      • plasma is the liquid part that carries all the components of blood
      • Blood contains red and white blood cells and platlets, hormones, antibodies, water, CO2, urea and digested food.
      • Blood vessles
        • arteries carry blood under high pressure AWAY from the heart. therefore, they have to be thick and elastic
        • Capillaries are one cell thick and can carry blood really close to every cell in the body so substances can diffuse in and out.
        • Veins take blood back to the heart at a much lower pressure sob they don't have to be as thick
        • valves stop the backflow of blood


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