Question

Southern blot technique is used for the detection of
A. DNA
B. RNA
C. Protein
D. RNA and DNA

Answer 1

Hint:-Southern blot hybridization using radioactive VNTR (a satellite DNA as a probe that shows very high degree of polymorphism) is a technique used in DNA fingerprinting which is developed by Alec Jeffreys. It is also used in immunogenetics and molecular biology.

Complete step-by-step solution:- The basis of DNA fingerprinting is VNTR (a satellite DNA as a probe that shows a very high degree of polymorphism). This technique of DNA was developed by Alec Jeffreys. This technique, as used earlier, involved Southern blot hybridization using radiolabeled VNTR as a probe. This process includes:
1. Isolation of DNA
2. Digestion of DNA
3. Separation of DNA fragments is done by electrophoresis, where agarose gel is the medium or (RFLP Restriction Fragment Length Polymorphism).
4. DNA fragments are transferred or blotted to synthetic membranes such as nitrocellulose or nylon
5. Hybridisation using labelled VNTR probe
6. Detection of hybridized DNA fragments by autoradiography
7. Hybridisation is done with a VNTR probe, the autoradiogram gives many bands of different sizes. These bands have a specific characteristic pattern for each individual DNA. The sensitivity of the technique can be increased by use of polymerase chain reaction (PCR). Therefore DNA extracted from a single cell is enough to perform DNA fingerprinting analysis.
Thus the analysis of the DNA of interest is possible from the required sample.
Practical Applications:
1. Identification of DNA in a sample
2. Paternity-maternity disputes
3. Criminal identification process
4. Personal identification
5. Close relations of an intending immigrant.
6. The Southern Blot technique is for detection DNA. So the correct answer is option (A).
Additional Information: It is also used for -
1. Mapping of restriction site
2. For diagnosis of infectious diseases
3. Detection of cancer and prenatal diagnosis of genetic disease
Used to measure molecular weight of restriction fragments and to determine the relative amounts in different samples.

Note:- The Southern blot method is named after the British Biologist Edwin Southern, who first published it in 1975. Southern Blot is the scientific and well organised technique used in molecular biology, immunogenetics and other molecular methods to detect or identify DNA of interest from a mixture of DNA samples or determine a specific base sequence within a strand of DNA