agarosegelelektrofores

Agarosegel electrophoresis is a laboratory technique used to separate nucleic acid molecules, primarily DNA, by size. A thin slab of agarose, a polysaccharide derived from seaweed, is melted in a buffer solution and poured into a casting tray to form a uniform gel. Once solidified, wells are cut into the gel where small volumes of DNA sample are loaded.

The gel is placed in an electrophoresis chamber filled with running buffer. An electric field is applied across the gel: the negatively charged DNA molecules migrate toward the anode. Because agarose pores act as a molecular sieve, smaller fragments move more easily than larger ones, producing a size‑dependent pattern. After separation, the gel is stained with an intercalating dye such as ethidium bromide or SYBR Safe, which fluoresces under UV light, allowing visualization and documentation of the bands.

Typical agarose concentrations range from 0.5 % to 2 % for DNA fragments between a few hundred base pairs and several kilobases. Higher concentrations give better resolution of small fragments, while lower concentrations accommodate larger fragments. Agarosegel electrophoresis is widely used in cloning, restriction digest analysis, PCR product assessment, and DNA fingerprinting. Its popularity stems from its simplicity, low cost, and ability to resolve DNA over a wide size range.

Key advantages include gentle handling of DNA because the gel matrix prevents shear forces, and the ability to recover bands for downstream applications. Disadvantages involve limitations in resolving very large fragments above 10 kb and the slow migration of very small fragments when using high agarose concentrations. Nevertheless, agarosegel electrophoresis remains a cornerstone method in molecular biology laboratories worldwide.