Intro to genetic material and nucleic acid structure

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  • Introduction to genetic material and nucleic acid structure
    • Experiements
      • Avery 1940
        • Staphylococcus bacteria; rough and smooth. Kill S and feed it to R. R converts to S (transformation principle)
          • Purify S type DNA and RNA to show it was these causing it and not proteins
            • Limitation as not all S purified
      • Hershey Chase 1952
        • Phosphate is in DNA (not proteins). Sulphate is vice versa.
          • Viruses with labelled DNA made a new virus with labelled DNA (wasn't as radioactive though)
          • Viruses with labelled proteins made a virus with normal DNA but with labelled phage ghosts
    • DNA
      • Nucleotide
        • Phosphate, pentose sugar, nitrogenous base
        • Purines bigger, have 2 rings and 9 atoms (adenine guanine)
          • Chargaff's rule: DNA is 50% of each. A=T, G=C
            • Pyrimidines smaller, have 1 ring and 6 atoms (cytosine, thymine, uracil)
        • Pyrimidines smaller, have 1 ring and 6 atoms (cytosine, thymine, uracil)
      • RNA
        • Carbon 2 has a hydroxyl group (ribose)
        • Uracil raplaces thymine
      • DNA carbon 2 loses its hydroxyl
        • Carbon 2 has a hydroxyl group (ribose)
      • Phosphate group attached to carbon 5. Nitrogenous group attached to carbon 1.
        • RNA
          • Uracil raplaces thymine
      • DNA and RNA interactions
        • Chain built by joining the 3rd carbon of one nucleotide with the phosphate of the other
          • Thus polynucleotide chains have polarity (5' to 3') and vice versa
          • Chain built in addition at 3' end
    • Double Helix
      • Watson and Crick 1953
      • Sugar phosphate backbone on outside
      • Helix right handed
      • Bases bound by hydrogen bonds (GC = 3) (AT=2)
      • Two strands antiparallel (opposite polarity)

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