What is Gel Electrophoresis?

Gel electrophoresis is a technique that is used to separate macromolecules such as proteins, DNA and RNA based on their charge and size. It is used in molecular biology and biochemistry to separate a mix of DNA and RNA based on their length and to separate proteins by charge.

In this technique, a polyacrylamide or agarose gel is prepared and placed in an electrophoretic chamber filled with a buffer and connected with a power source. This generates an electric field with negative charge at one end and positive at another. The negative charge pushes the molecules through the gel, whereas the positive charge pulls the molecule through the gel. Larger molecules move slowly in the gel whereas smaller molecules run faster and form distinct bands on the gel which can be analysed under UV light.

Gel electrophoresis can be conducted in either horizontal gels or vertical gels depending on the molecule to be separated. Let us know a little about them before differentiating between them.

Horizontal Gel Electrophoresis

In horizontal gel electrophoresis, the gel is cast horizontally and placed in a chamber (filled with a running buffer) that is divided into two sections with the gel in the middle, forming positive charge at one end and negative at the other. A continuous running buffer is used in horizontal gel electrophoresis. The running buffer creates a charge gradient on application of current. Additionally, the buffer cools the gel which gets heated up when electric current is applied.

It is not possible to use a discontinuous buffer in a horizontal system because the two sections are connected with each other. A horizontal gel is usually made up of agarose which has larger pores and is used for nucleic acid separation. Acrylamide gel cannot be used in this system because this system is in contact with oxygen and acrylamide cannot polymerize in the presence of oxygen.

Vertical Gel Electrophoresis

Vertical gel electrophoresis is a slightly trickier technique where the gels are cast in a vertical direction. A discontinuous buffer system is used in this technique where the top compartment has cathode and the bottom compartment has anode. The gel is prepared by pouring a thin layer between two glass plates and placed such that the bottom of the gel is immersed in a buffer in one compartment and the top is immersed in a buffer in another compartment. On application of current, a small amount of buffer travels from through the gel from the top compartment to the bottom compartment.

Vertical gels are cast using acrylamide which has finer pores that achieves greater resolution and separation. It is used in separating a mixture of proteins.

Horizontal vs Vertical Gel Electrophoresis

Visit BYJU’S Biology for more updates.

Also see:

• Classification of Bryophytes
• Lipase Enzyme
• Slime Moulds