Biotechnology & Genetic Engineering

Genetic engineering moves or edits genes on purpose. The classic toolkit uses bacterial enzymes and vectors (plasmids and viruses) to carry a chosen gene into a new cell.

Cut, carry, paste

• Find the target gene using a probe (a labelled complementary sequence).
• Cut it out with restriction enzymes, which recognise specific sequences and often leave overhanging sticky ends.
• Carry it in a vector — usually a bacterial plasmid — cut with the same enzyme so the sticky ends match; DNA ligase seals it in.
• Insert the vector into a host cell by transformation, electroporation or microinjection.

A gene cut with a restriction enzyme is pasted into a plasmid vector cut by the same enzyme.

CRISPR

CRISPR–Cas9 is a precise editor: a guide RNA leads the Cas9 enzyme to an exact DNA sequence, where it cuts so a gene can be disabled, corrected or replaced. It has made editing and transferring genes far faster and cheaper — and enables the design of new proteins.

Transgenic organisms

An organism carrying a gene from another species is transgenic. Uses include bacteria that make human insulin, pest- or drought-resistant crops, and more. The benefits come with unexpected consequences that need monitoring and risk assessment.