An enzyme that cleaves/cuts DNA into fragments at specific sites within molecules known as restriction sites, by making two incisions, one through each sugar-phosphate backbone (i.e. each strand) of the DNA double helix. They can be used in biotechnology
DNA Ligase

A specific type of enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. Has a role in both DNA replication and the repair of DNA strands.
PCR (Polymerase Chain Reaction)

A method used to artificially replicate DNA, using a strand of DNA and free nucleotides. Each cycle doubles the amount of DNA, and the process is performed with a machine known as a thermocycler
Steps of PCR: Denaturing

The strands of DNA are broken apart without the use of DNA helicase, by heating the strands to 95°c, which breaks the hydrogen bonds.
Steps of PCR: Annealing:
The reaction is cooled to 50-60°C, allowing primers to bind their complimentary sequence to each strand, or anneal.
Steps of PCR: Extending
The reaction is raised to 72°C, and TAC polymerase adds free nucleotides to each strand until a stopcodon is reached
Applications of PCR

Identifying natural variations/mutations in DNA, a genetic screening to identify carriers of genetic disorders and disease
