PCR

Also called

polymerase chain reaction · DNA amplification · thermocycler · thermal cycler · denaturation · annealing · extension · primers · Taq polymerase · Thermus aquaticus · DNA copies · gene amplification · biotechnology tools · पीसीआर · डीएनए प्रवर्धन · प्राइमर

Topics

• PCR (polymerase chain reaction) makes millions of copies of a chosen piece of DNA in a test tube.
• The tube holds template DNA, two primers, Taq polymerase and the four nucleotides, cycled through three temperatures.
• Denaturation at about 94 °C breaks the hydrogen bonds, so the two strands of the DNA separate.
• Annealing at about 50–60 °C lets the two short primers bind to their complementary sites on each strand.
• Extension at about 72 °C: Taq polymerase adds nucleotides to each primer, making a new strand along the template.
• Taq polymerase comes from the bacterium Thermus aquaticus, so it is not destroyed by the 94 °C step.
• Each cycle doubles the DNA: 1 to 2 to 4 to 8; about thirty cycles give roughly a billion copies.
• A thermocycler changes the temperature automatically, so a whole run takes only a few hours.
• Amplified DNA is used in gene cloning, detecting pathogens and genetic disorders, and DNA fingerprinting.

About this model

A GLB file of about 291 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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