Question

Agarose which is extracted from seaweeds is most widely used in
(a) Gel electrophoresis
(b) Spectrophotometry
(c) Tissue culture
(d) PCR

Answer 1

Hint: This method is used for separating fragments of DNA based on their size. Another novel application of this is to separate or characterize metal or metal oxide nanoparticles. It uses a gel as a sieving medium.

Complete answer:
The agarose which is extracted from seaweeds is most widely used in gel electrophoresis.
It involves the separation and isolation of DNA fragments in recombinant DNA technology. The cutting of DNA by restriction endonucleases results in a mixture of small and large fragments of DNA. These fragments can be sorted by a technique known as gel electrophoresis. Since DNA fragments are negatively- charged molecules they can be separated by forcing them to shift towards the anode under an electric field through a medium/matrix. Nowadays the most commonly used matrix is agarose which is a natural polymer extracted from seaweeds. The DNA fragments get sorted according to their size through sieving effects provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves in the matrix.
- Electrophoresis is the movement of a charged particle in an electrical current.
- Agarose gel electrophoresis is employed to check the progression of digestion by a restriction enzyme.
So, the correct answer is, “Gel electrophoresis”.

Note:
- Recombinant DNA Technology: Also called ‘genetic engineering’ includes techniques to alter the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism.
- Restriction enzymes belong to a wider class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases.
- ‘Exonucleases’ cut and remove nucleotides from the ends of the DNA whereas, ‘endonucleases’ make cuts at specific positions within the length of the DNA.