AQA Genetic comparisons using DNA and Proteins

Just things you need to know about DNA

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  • Created by: Agent006
  • Created on: 02-04-12 12:01

DNA Hybridisation

  • Extract the same protein fron the two organisms and then radioactive label one of the species.
  • Heat up the strands.So hydogen bond are broken.
  • Allow to mix and cool (one strand from each species) Hydrogen bond form when there are complementary bases.
  • Heat the hybrid strand. Increase the tempreture in stages. E.g 2 degrees every minute.
  • The highr the tempreture reached means more hydogen bonds, so more complementary bases which show that they are more closely related.
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Comparing Amino Acid Sequences

  • Proteins consists of three Pair bases which consists of three base pairs (a triplet).
  • Comparing the sequence of amino acids in a particular protein in two different species can give an indication of how closely the two species are related.
  • The ptrotein must be common to both species.
  • the more amino acids that they share means that they are mostly related.
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Immunological comparison of proteins

  • The proteins of different species can be compared using immunological techniques.
  • the principle behind this methods is the fact that antibodies of one species will respond to specific antigens on proteins.
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Differences between DNA and RNA


  • double stranded
  • deoxyribose sugar
  • contains thymine
  • bases are:
    • Guamine and Cytosine
    • Adenine and Thymine


  • single stranded
  • ribose sugar
  • contains Uracil
  • bases are:
    • Guamine and Cytosine
    • Adenine and Uracil
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Tilly - Team GR


good cards thanks.

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