Southern blotting

Southern blotting is a laboratory technique used in molecular biology for detection of a specific DNA sequence in DNA samples. It was named after the British biologist Edwin Southern, who first published about the procedure in 1975.

Procedure

The Southern blot procedure begins with a sample of DNA, which is then cut into smaller fragments using a restriction enzyme. These fragments are then separated by size through a process called gel electrophoresis. After the separation, the fragments are transferred to a membrane (blotting), and then they are exposed to a probe - a single DNA sequence that has been labelled with a radioactive or chemical tag. If the probe sequence is present in the sample, it will bind to the DNA fragments on the membrane, allowing for detection.

Applications

Southern blotting has many applications in molecular biology and genetics, including:

• Identification of specific DNA sequences within a complex mixture
• Determination of the molecular weight of a restriction fragment
• Analysis of the structure of various fragments
• Determination of the sequence homology among different genes

Limitations

While Southern blotting is a powerful technique, it also has some limitations. It is a time-consuming process and requires a large amount of DNA. In addition, the procedure is sensitive to changes in the DNA sequence, which can lead to false positives or negatives.

See also

• Northern blot
• Western blot
• Eastern blot

Southern blotting Resources
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