What is gel electrophoresis | Types and principles
Gel Electrophoresis is a widely used analytical method in molecular biology and biotechnology.
Widely practiced for the separation of particles like viruses, small DNA fragments and nucleic acids and proteins. Also used after the PCR, to separate the DNA copies according to their quality.
Moreover, the electrophoresis method relies on the basic principle that the charged particles in a sample will migrate if an electric field applied to it.
Therefore, once electric field applied, the particle in the solution will migrate according to the charge or size.
Above all, widely used gels like polyacrylamide and agarose are commonly used .
This gel gives sieving or separating effect, and the particle separated by both size and charge.
Small molecules can travel faster than the larger one, also the negative charged particles will move towards anode. Similarly, positive charged particles will move towards cathode, in this way particle gets separated by size and charge.
Electrophoresis of cationic particle is called cataphoresis. Likewise, that of anionic particle called anaphoresis.
Types of Electrophoresis
There are different types of electrophoresis but the most commonly and vividly used are mentioned below:
Capillary electrophoresis – molecules separated on the electrophoresis basis by using a capillary tube. To clarify, the molecules separated by running them through the capillary tubes. Accuracy higher but less quantity samples can be loaded at a time.
Native gels electrophoresis – protein run without SDS. Therefore, no proteins will get denatured in this method.
SDS – PAGE – Full form : Sodium Dodecyl Sulfate – Polyacrylamide gel electrophoresis. To clarify, SDS a detergent which can denature the protein and binds to the hydrophobic site of the molecule. Therefore, becoming the most dominant negative charge of the complex.
Here, the proteins are run through gel, polyacrylamide. Therefore, the particle density and size can be varied.
Electrofocusing gel – A gel with a pH gradient used here. As the particle travels through the gradient.
Meanwhile, it will loose protons and finally gets stucked at a point with no pH.
DNA Agarose gels – Here, agarose gels used to separate large fragments of DNA. The method used to separate according to the particle sizes. Here, no SDS needed because, DNA being negatively charged.
Above all, particle size sensitivity can be adjusted by adjusting gel density.
Sequencing gels – method used to separate smaller DNA fragments with a greater resolution. Firstly, the DNA denatured using heat and at the same time passed through polyacrylamide gel. Moreover, DNA which differ by 1 or 2 base can be separated more accurately.
Gel Electrophoresis applications
Applied for the estimation of DNA molecules.
Helps in mapping cloned DNA.
Analyzing the PCR products.
Gel electrophoresis widely used in forensics, molecular biology and genetic engineering.
Used in verification of amplified DNA using PCR.
Checking the quality of extracted DNA.
Gel electrophoresis a widely used technique, more modernized. Moreover, to determine the DNA fragment quality. In addition, used after the PCR to seperate and extract the DNA products.
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