PCR, gel electrophoresis, recombinant DNA and genetic engineering, DNA sequencing and profiling, and the ethics of GMOs.
Gene technology manipulates DNA for research, medicine, agriculture and forensics.
The polymerase chain reaction (PCR)
PCR amplifies DNA (makes millions of copies) in cycles of three temperatures:
- Denaturation (~95 °C) — heat breaks the hydrogen bonds, separating the two strands.
- Annealing (~55 °C) — primers bind to the start of the target sequence on each strand.
- Extension (~72 °C) — Taq polymerase (a heat-stable enzyme) adds nucleotides, building new strands.
Each cycle doubles the DNA, so the amount rises exponentially (2ⁿ after n cycles).
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