Nucleic Acids

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  • Created by: Buffya
  • Created on: 28-05-13 16:51
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  • Nucleic acids
    • DNA
      • Contains the sugar dexoyribose
      • DNA is a stable polynucleotide molecule. It acts as an information store because the bases projecting from the backbone act as a coded sequence
      • Two polynucleotide strands run  parallel to each other with hydrogen bonds between the bases
        • The strands run in opposite directions - antiparallel and twist - double helix
        • A is complementary to T, C is to G
      • Copying in interphase
        • Double helix untwisted
          • Hydrogen bonds broken exposing bases
            • Free DNA nucleotides hydrogen bond with exposed bases
              • Covalent bonds seal the sugar-phosphate backbone
                • Semi-conservative replication catalysed by DNA polymerase
      • A gene is a length of DNA that codes for one polypeptide - occupies a locus on chromosomes
    • RNA
      • Contains the sugar ribose
      • Contains uracil instead of thymine. Base pairing of A-U, C-G
      • There are three forms
        • ribosomal RNA (rRNA)
          • Shown as a two-lobed structure
        • transfer RNA (tRNA)
          • Is around 80 nucleotides long which folds up and is stabilised by hydrogen bonds
        • messenger RNA (mRNA)
          • A single strand complementary to the DNA template strand
      • A gene can be exposed by splitting hydrogen bonds in that region
        • RNA nucleotides form a complementary strand (mRNA)
          • mRNA leaves through nuclear pore and attaches to a ribosome
            • tRNA brings amino acids in order according to base sequence on mRNA
    • Nucleotides
      • Made of one phosphate group, one sugar molecule and one organic nitrogenous base
      • Five possible bases
        • Pyrimidines
          • Thymine
          • Uracil
          • Cytosine
        • Purines
          • Adenine
          • Guanine
          • Excess purines form uric acid which can cause gout
      • A condensation reaction between the phosphate of one and the sugar of another joins them



This Mind Map has a good use of colour to separate the key ideas and has a well organised layout. This topic is studied by most GCE Biology students so this Mind map would be helpful to a number of students. It is usually recommended that images are added to mind maps to make them more memorable so perhaps this could be done after download.Team this  up with some notes and a set of flashcards for a more complete set of resources.

Izzy Mason

Really useful thanks :)

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