Question

Gel electrophoresis is used for
A. Construction of recombinant DNA by joining with cloning vectors
B. Isolation of DNA molecules
C. Cutting of DNA into fragments
D. Separation of DNA fragments according to their size

Answer 1

Hint: Gel electrophoresis is a method that is widely used in laboratories to separate the molecules such as DNA, RNA, or protein-based on their size, under the influence of an electric field, as a result of this they migrate in the direction of the electrode bearing the opposite charges i.e. positively charged molecules move towards cathode (negative electrode) and the negatively charged molecule move towards anode (positive electrode).

Complete Answer:
The movement of the charged molecule is known as “migration”. This technique can be followed only after cutting of DNA fragments by “restriction enzyme”, and the fragments of DNA are formed.

Electrophoresis was developed by A.Tiselius in 1937. This technique is performed in gel consists of a permeable matrix so that molecules of similar charge can be separated based on their size. A smaller molecule can travel through the gel more quickly on the other hand larger molecules that migrate slowly and hence they cover a shorter distance.

Therefore, the correct answer is the separation of DNA fragments according to their size.

Note: Electrophoresis is a technique that is used to distinguish between several DNA molecules according to their size under the effect of the electric field. It is performed on the agarose gel. Now- a -days, the most widely used is agarose that is a polysaccharide that is extracted from seaweeds.