Question

The identification of specific DNA sequence by Southern Blotting involves the following procedures:
A) Digestion of the DNA with a restriction enzyme
B) Fractionation of DNA fragments
C) Transfer of ssDNA molecules from gel to an absorbent sheet
D) Hybridization of radioactively labelled probe to target DNA
What is the correct sequence in which these procedures are executed?

• A. A \(\rightarrow\) B \(\rightarrow\) C \(\rightarrow\) D
• B. A \(\rightarrow\) D \(\rightarrow\) B \(\rightarrow\) C
• C. D \(\rightarrow\) C \(\rightarrow\) B \(\rightarrow\) A
• D. B \(\rightarrow\) C \(\rightarrow\) A \(\rightarrow\) D

Hint:

Southern blotting steps:
Digest \(\rightarrow\) Electrophorese \(\rightarrow\) Transfer \(\rightarrow\) Hybridize \(\rightarrow\) Detect.
Remember: "Digest, Separate, Transfer, Probe."

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
Southern blotting is a molecular biology technique used to detect specific DNA sequences in a complex mixture of DNA fragments.
It was developed by Edwin Southern in 1975.

Step 2: Detailed Explanation:
The correct sequence of steps in Southern blotting is:
A \(\rightarrow\) B \(\rightarrow\) C \(\rightarrow\) D:
1. Digestion (A): DNA is digested with restriction enzymes to generate smaller fragments.
2. Fractionation (B): DNA fragments are separated by size using agarose gel electrophoresis.
3. Transfer (C): DNA fragments are denatured to single-stranded DNA (ssDNA) and transferred to a nitrocellulose or nylon membrane.
4. Hybridization (D): A radioactively labelled probe is hybridized to the target DNA sequence on the membrane.
Thus, the correct sequence is A \(\rightarrow\) B \(\rightarrow\) C \(\rightarrow\) D.

Step 3: Final Answer:
Thus, the correct sequence is A \(\rightarrow\) B \(\rightarrow\) C \(\rightarrow\) D, which corresponds to option (A).
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