Question

The recent techniques used for separating fragments of DNA is 

A. Northern blotting

B. Southern blotting

C. Eastern blotting

D. Western blotting

Answer 1

Hint: Blotting techniques were developed to discriminate between fragments of nucleic acids and proteins. One of the processes is used to separate fragments of DNA and is known as electrophoresis.

Complete step by step answer:

- In Southern blotting, the fragments of DNA are separated by PAGE that are cut by restriction enzymes. Then the blot is transferred to specialised membranes and visualised with labeled probes hybridization. The presence of a specific DNA sequence within a mixture via agarose gel electrophoresis has been determined with the use of the Southern blotting technique. 

- RNA is being separated by Northern blotting. RNA molecules have defined lengths and they are shorter; cutting by restriction enzymes is not required. RNA: Northern blots protocols begin with RNA isolation, and separation techniques vary depending on RNA size. Large RNAs are separated by electrophoresis on a formaldehyde agarose gel or glyoxal agarose gel, which prevents regular base pairing and maintains RNA as a denatured state. Small RNAs are separated on a denaturing (urea) polyacrylamide gel. The nylon membrane gets RNA from the gel, then incubated with radioactivity or non isotopically labeled RNA, DNA, or oligodeoxynucleotide probes. Washing with a buffer removes the unhybridized search. Radiolabeled probes and enzymatically labeled probes are visualized with X-ray film and chemiluminescence, respectively.

- Nucleic acids have not been separated by Western blotting.

- Western blot is an invaluable lab technique used to detect proteins in a tissue or a blood sample.

Hence, option (B):  Southern blotting is the correct answer.

Note:

To separate and characterize DNA, in molecular biology Southern blotting is a common technique used. To analyze protein post-translational modifications the eastern blot is a biochemical technique used such as lipids. Thus, the biochemical technique Eastern blotting can be considered an extension of Western blotting.