DNA amplification using PCR Flashcards
1
Q
Equipment (5)
A
- Thermocycler
- DNA sample
- Taq polymerase
- Nucleotides
- primers
2
Q
Outline the method
A
DNA sample is placed into tube in thermocycler with nucleotides, primers and polymerase. Step 1: denaturation = DNA heated for 1min at 94°C to denature it. This breaks the H bonds between nucleotides and makes the double stranded DNA, single stranded.Step 2: annealing = temperature reduced to 54°C.Bonds form between primers and the template strands . This will allow the polymerase enzyme to start to copy the template.
Step 3: extension = carried out at 72°C. This is the optimum for taq polymerase enzyme. The bases are placed in their correct position, extending the strand from the primer.
3
Q
Possible evaluation issues (2)
A
- The amount of DNA doubles each cycle (steps 1-3) therefore a considerably amount of copied DNA can be made for use in DNA fingerprinting etc.
- 35 cycles ( a few hrs) = 34 billion copies
