Gene Technology

Gene technology encompasses the techniques used to study, manipulate, and alter DNA. These tools have revolutionised biology, medicine, agriculture, and forensic science. At A-Level, you need to understand the key techniques — restriction enzymes, PCR, gel electrophoresis, genetic fingerprinting, gene therapy, genetic modification, and genome editing — as well as their applications and the ethical debates they raise.

Key Definition: Gene technology (also called genetic engineering or recombinant DNA technology) is the manipulation of an organism's DNA to alter its characteristics, usually by introducing a gene from another organism.

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Restriction Enzymes (Restriction Endonucleases)

Key Definition: A restriction enzyme (restriction endonuclease) is a bacterial enzyme that cuts DNA at or near a specific recognition sequence (restriction site) — a short palindromic sequence of bases, typically 4–8 base pairs long.

Bacteria naturally produce restriction enzymes as a defence mechanism against bacteriophages (viruses that infect bacteria). They cut foreign DNA while the bacterium's own DNA is protected by methylation of its recognition sites.

Sticky Ends vs Blunt Ends