Electrophoresis

Electrophoresis is a separations technique that is based on the the mobility of ions in an electric field. Positively charged ions migrate towards a negative electrode and negatively-charged ions migrate toward a positive electrode.For safety reasons one electrode is usually at ground and the other is biased positively or negatively.

Ions have different migration rates depending on their total charge, size, and shape, and can therefore be separated. Instrumentation An electrode apparatus consists of a high-voltage supply, electrodes, buffer, and a support for the buffer such as filter paper, cellulose acetate strips, polyacrylamide gel, or a capillary tube.

Electrophoresis of positively charged particles is called cataphoresis, while electrophoresis of negatively charged particles (anions) is called anaphoresis. Electrophoresis is a technique used in laboratories in order to separate macromolecules based on size. The technique applies a negative charge so proteins move towards a positive charge.

This is used for both DNA and RNA analysis. Polyacrylamide gel electrophoresis (PAGE) has a clearer resolution than agarose and is more suitable for quantitative analysis.

Types of Electrophoresis

1.Capillary electrophoresis

Gel electrophoresis

Paper electrophoresis

2. Slab electrophoresis

Zone electrophoresis

Immunoelectrophoresis

Isoelectrofocusing

Types of Gel electrophoresis

Many types of gels are usually used as the support medium for electrophoresis. This may be in slab or tube form based on benefits. Gel slabs enable many samples to be run simultaneously therefore frequently used in laboratories. The tube gels gives better resolution of the results therefore are often selected for protein electrophoresis.

The agarose gel is commonly used for electrophoresis of DNA. It has a large pore structure allowing larger molecules to move easily but it is not suitable for sequencing smaller molecules.

The polyacrylamide gel electrophoresis (PAGE) has a better clear resolution than agarose gel making it suitable for quantitative analysis. This helps to identify how proteins bind to DNA.

Factors that affect DNA agarose gel electrophoresis

Electric field: Voltage applied current and charge of particles.

Nucleic acid sample: Type, purity and quantity.

Buffer: Concentration, pH of buffer and buffer type.