gelelektroforeesi

Gelelektroforeesi, known in English as gel electrophoresis, is a laboratory technique used to separate macromolecules, typically nucleic acids and proteins, based on size and charge by applying an electric field to a gel matrix. In most cases, smaller fragments migrate faster through the gel than larger ones, allowing estimation of fragment length or molecular weight. DNA and RNA are negatively charged and migrate toward the anode, while proteins can be separated under varying conditions depending on their charge and conformation.

Two main gel systems are commonly used. Agarose gels are suited for separating nucleic acids ranging from a few hundred to tens of thousands of base pairs, while polyacrylamide gels provide higher resolution for smaller fragments and are often used for proteins or single-nucleotide differences. Denaturing systems, such as denaturing polyacrylamide gels, are used when primary sequence information or single-nide differences must be resolved. Buffers such as TAE or TBE maintain pH and conductivity during the run. In protein analysis, SDS-PAGE is frequently used to give proteins a uniform charge-to-mass ratio.

The procedure typically involves preparing samples with loading dyes, loading them into the gel, and running the gel at a constant voltage in an appropriate buffer. After separation, gels are stained with dyes (for example, ethidium bromide or safer alternatives for nucleic acids) or detected by fluorescent tags to visualize the bands. The position of bands is compared to molecular weight or size ladders to infer fragment sizes.

Applications include verification of PCR products, restriction digests, genomic DNA quality, RNA integrity, and protein analysis; it is also used in forensics, diagnostics, and research. Safety considerations include handling mutagenic stains and, for acrylamide gels, neurotoxic monomers, with appropriate protective equipment and disposal.