🧪 General Principles🟢 BasicMolecular Biology Techniques

The Polymerase Chain Reaction (PCR)

A laboratory method that makes millions of copies of a chosen stretch of DNA, so that a tiny sample can be studied or detected.

Key points

PCR copies (amplifies) a specific piece of DNA over and over, so that even a trace amount becomes enough to study.
It needs the DNA template, two short primers that flank the target, a heat-stable DNA polymerase (such as Taq), free nucleotides and a buffer.
Each cycle has three steps: denaturation (heat splits the strands apart), annealing (the primers bind their targets), and extension (the polymerase builds new strands).
Because each cycle ideally about doubles the DNA, the amount rises roughly exponentially, so about thirty cycles can make millions of copies.
A heat-stable polymerase is essential because the high denaturation temperature would destroy an ordinary enzyme in each cycle.
PCR is used to diagnose infections and genetic diseases, in forensic identification and in research; reverse-transcription PCR first converts RNA into complementary DNA (cDNA), which is then amplified.

Denature, anneal, extend, repeat: heat splits the strands, primers mark the target, and a heat-stable polymerase roughly doubles it every cycle.

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🧪 General Principles🟢 BasicMolecular Biology Techniques

A laboratory method that makes millions of copies of a chosen stretch of DNA, so that a tiny sample can be studied or detected.

PCR copies (amplifies) a specific piece of DNA over and over, so that even a trace amount becomes enough to study.
It needs the DNA template, two short primers that flank the target, a heat-stable DNA polymerase (such as Taq), free nucleotides and a buffer.
Each cycle has three steps: denaturation (heat splits the strands apart), annealing (the primers bind their targets), and extension (the polymerase builds new strands).
Because each cycle ideally about doubles the DNA, the amount rises roughly exponentially, so about thirty cycles can make millions of copies.
A heat-stable polymerase is essential because the high denaturation temperature would destroy an ordinary enzyme in each cycle.
PCR is used to diagnose infections and genetic diseases, in forensic identification and in research; reverse-transcription PCR first converts RNA into complementary DNA (cDNA), which is then amplified.

Denature, anneal, extend, repeat: heat splits the strands, primers mark the target, and a heat-stable polymerase roughly doubles it every cycle.