4C - Polymerase Chain Reaction

polymerase chain reaction (PCR)

a laboratory technique used to produce many identical copies of DNA from a small initial sample

amplify

to increase the quantity of a molecule by making many copies

primer

a short, single strand of nucleic acids that acts as a starting point for polymerase enzymes to attach

restriction endonuclease

any enzyme that acts like molecular scissors to cut nucleic acid strands at specific recognition sites. Also known as a restriction enzyme

Taq polymerase

a heat-resistant DNA polymerase enzyme isolated from the bacteria Thermus aquaticus, which amplifies a single-stranded DNA molecule by attaching complementary nucleotides

Denaturation

DNA is heated to approximately 90-95 °C to break the hydrogen bonds between the bases and separate the strands, forming single-stranded DNA.

Annealing

the single-stranded DNA is cooled to approximately 50-55 °C to allow the primers to bind to complementary sequences on the single-stranded DNA.

Elongation

the DNA is heated again to 72 °C, which allows Taq polymerase to work optimally. Taq polymerase binds to the primer, which acts as a starting point, and begins synthesising a new complementary strand of DNA.

forward primer

a DNA primer that binds to the 3' end of the template strand and reads the DNA in the same direction as RNA polymerase

reverse primer

a DNA primer that binds to the 3' end of the coding strand and reads the DNA in the reverse direction to RNA polymerase

Thermal cycler

a laboratory apparatus which alters the temperature in pre-programmed steps for temperature-sensitive reactions like PCR

Nucleotides in DNA

Adenine, Thymine, Guanine, Cytosine