Arrange the correct sequence of steps for gel electrophoresis.
(A). Load this DNA into the agarose gel matrix
(B). Cutting the DNA fragments by using a restriction enzyme
(C). Use ethidium bromide for DNA staining
(D). Separated bands of DNA are cut out from agarose gel
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (B), (A), (C), (D)
(B) Cutting the DNA fragments by using a restriction enzyme — first. Restriction endonucleases cut the DNA into fragments of different sizes. These fragments are what the gel separates.
(A) Load this DNA into the agarose gel matrix — second. The DNA is negatively charged. In the electric field it moves towards the anode through the agarose gel, which acts like a sieve. Smaller fragments move farther.
(C) Use ethidium bromide for DNA staining — third. DNA bands cannot be seen in the gel as they are. They are stained with ethidium bromide and seen under UV light as bright orange bands.
(D) Separated bands of DNA are cut out from agarose gel — last. The wanted bands are cut out and the DNA is taken out of the gel piece. This step is called elution. The purified DNA is then joined to cloning vectors.