Gel electrophoresis

Definition

A laboratory technique that separates charged biomolecules—DNA, RNA, or proteins—by size and charge as they migrate through a porous gel matrix under an electric field. The gel acts as a molecular sieve: smaller molecules travel farther than larger ones, producing discrete bands that can be visualized with stains or fluorescent dyes.

Etymology

From 'gel' (gelatinous matrix) + 'electrophoresis' (Greek: electron 'amber/electricity', phorein 'to carry'), coined for techniques using electric fields to move charged particles.

Example

DNA barcoding of museum beetle specimens often employs agarose gel electrophoresis to verify PCR-amplified cytochrome oxidase I (COI) fragments before sequencing, confirming amplicon size (~650 base pairs) and purity.

Synonyms

• gel electrophoretic separation

Related Terms

• agarose gel
• polyacrylamide gel
• DNA barcoding
• PCR
• SDS-PAGE
• electrophoretic mobility
• molecular marker
• population genetics

Usage Notes

Agarose gels (lower resolution, larger pore size) are standard for DNA/RNA fragments; polyacrylamide gels (higher resolution) resolve smaller nucleic acids or proteins. SDS-PAGE denatures proteins and separates by mass alone. In arthropod systematics, gel electrophoresis has been largely superseded by capillary electrophoresis and direct sequencing, but remains essential for rapid size-checking and teaching laboratories. Results are described as 'run on a gel' or 'resolved by electrophoresis,' not 'electrophoresed' as a verb.