Gel electrophoresis
Read the following passage carefully and answer the given questions.
The cutting of DNA by molecular scissors results in fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis. Since DNA fragments are negatively charged molecules, they can be separated by forcing them to move toward electrode under an electric field through a matrix. Nowadays, most commonly used matrix is agarose, which is a natural polymer. The DNA fragments resolve according to their size through sieving effect provided by agarose gel. Hence, smaller fragment size, farther it moves. The separated DNA fragments can be visualized only after staining DNA with a dye followed by exposure to radiation. The separated bands of DNA are cut out from agarose gel and extracted from gel piece. The DNA fragments purified in this way are used in construction recombinant DNA by joining them with cloning vectors.
Identify the source of agarose used in gel electrophoresis.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Marine weeds
Agarose is a natural polymer. It is the matrix most commonly used for gel electrophoresis, and it is extracted from sea weeds (marine algae). The DNA fragments move through the pores of the agarose gel, and the gel sorts them by size.
(1) Marine bacteria — Incorrect. Agarose is not taken from bacteria.
(2) Marine fungi — Incorrect. Agarose is not taken from fungi.
(3) Marine weeds — Correct. This is the source of agarose.
(4) Marine cyanobacteria — Incorrect. Cyanobacteria are bacteria that photosynthesise. They are not the source of agarose.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Restriction Enzymes – …
