Southern blotting is a technique used to detect specific DNA sequences in a DNA sample. It involves extracting DNA from cells, cutting the DNA into fragments using restriction enzymes, separating the fragments via gel electrophoresis, transferring the DNA fragments to a membrane, and using a labeled probe to detect fragments that are complementary to the probe through hybridization. Southern blotting is useful for identifying mutations, DNA fingerprinting, and detecting DNA in applications like prenatal screening and forensics. While effective for detecting specific DNA sequences, it is a complex, time-consuming, and labor-intensive technique.

1. Anushi Jain
Roll No : 12
Paper 3
MSc-I

2.  Blotting
 Types of blotting
 Southern blotting
 Principle
 Apparatus
 Steps involved in southern blotting
 A schematic view of southern blotting
 Application
 Advantages and Disadvantages

3. • A blot, in molecular biology and genetics, is a method of
transferring proteins, DNA or RNA, onto a carrier.
• The term "blotting" refers to the transfer of biological
samples from a gel to a membrane and their subsequent
detection on the surface of the membrane.
• Technique for transferring DNA ,RNA and Proteins onto a
carrier so they can be separated, and often follows the use
of a gel electrophoresis.

4. Southern blotting
Northernblotting
Westernblotting

5. • A Southern blot is a method used
in molecular biology for DNA analysis.
•The method is named after its inventor,
the British biologist Edwin Mellor
Southern,In 1975.
•This method is also known as DNA
blotting/Southern hybridization.

6.  The key to this method is hybridization.
Hybridization: It is the process of forming a double-stranded DNA
molecule between a single-stranded DNA probe and a single-
stranded target DNA.
 There are 2 important features of hybridization:
• The reactions are specific-the probes will only bind to targets with
a complementary sequence.
• The probe can find one molecule of target in a mixture of millions
of related but non-complementary molecules.

7. APPARATUS

8. 1. Extract and purify DNA from cells;
2. DNA is restricted with enzymes;
3. Separated by electrophoresis;
4. Denature DNA;
5. Transfer to nitrocellulose paper;
6. Add labelled probe for hybridization to take place;
7. Wash off unbound probe;
8. Autoradiograph.

9. 1. Extract and purify DNA from cells;
2. DNA is restricted with enzymes;
3. Separated by electrophoresis;

10. 4. Denature DNA;
5. Transfer to nitrocellulose
paper;
6. Add labeled probe for
hybridization to take place;
7. Wash off unbound probe;
8. Autoradiograph.

11. DNA Fragments seen after autoradiography

13. • To identify specific DNA in a DNA sample.
• To Isolate desired DNA for construction of rDNA.
• Identify mutations, deletions, and gene rearrangements.
• Used in prenatal diagnosis of genetic diseases.
• In RFLP.
• In DNA fingerprinting:
 Paternity and Maternity Testing
 Criminal Identification and Forensics

14. • Effective way to detect a specific DNA sequence in a large,
complex sample of DNA.
• Can be used to quantify the amount of the present DNA.
• Cheaper than DNA sequencing.
• Complex and labor-intensive.
• Time consuming.