DNA technology

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  • Created by: 08rmorris
  • Created on: 26-03-15 17:18
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  • DNA technology
    • DNA fragments
    • Polymerase Chain Reaction (PCR)
      • 1. Start with a sample of the DNA to be amplified, and add the 4 nucleotides and the enzyme DNA polymerase
        • 2. Heat to 95 degrees celcius for 2 minutes to break the H bonds between the bee pairs and separate the two strands of DNA.
          • Normally (in-vivo) the DNAdouble helix would be separated by an enzyme
          • 3. Add primers to the mixture and cool to 40 degrees C. Primers are short lengths of dingle-stranded DNA that anneal to complementary sequences of double stranded DNA
            • The DNA is cooled to 40 to allow H bonds to form. There are 2 reasons for making short lengths of double stranded DNA
              • 1. The enzyme DNA polymerase requires some existing double stranded DNA to get it started
              • 2. Only the DNA between the primer sequences is replicated,so by choosing appropriate primers you can ensure that only a specific target sequence is copied.
            • 4. The DNA polymerase enzyme can now build new strands alongside each old strand to make double-stranded DNA. Each new nucleotide binds to the the old strand by complementary base pairing and is joined to the growing chain by a phosphodiester bond.
              • The enzyme used in PCR is derived from the thermophilic bacterium thermus aquaticus.
                • which grows naturally in hot springs at a temperature of 90 so it is not denatured by the high temperature in step 2.
                  • Its optimum temperature is about 72, so the mixture is heated to this temperature for a few minutes to allow replication to take place as quick as possible
              • 5.Each original DNA molecule has now been replicated to form two molecules
                • This cycle is repeated from step 2 and each time the number of DNA molecules double
                  • This is why it is called a chain reaction
  • The enzyme used in PCR is derived from the thermophilic bacterium thermus aquaticus.
    • which grows naturally in hot springs at a temperature of 90 so it is not denatured by the high temperature in step 2.
      • Its optimum temperature is about 72, so the mixture is heated to this temperature for a few minutes to allow replication to take place as quick as possible

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