Question

Which technique is specifically used to detect the presence of a specific DNA sequence in a sample?

• A. Western blotting
• B. Southern blotting
• C. Northern blotting
• D. ELISA

Hint:

{Blotting rule:}
Southern → DNA
Northern → RNA
Western → Protein

Answer 1

The Correct Option is B

Concept: Blotting techniques are widely used in molecular biology to detect specific biomolecules such as DNA, RNA, or proteins. Each blotting method is designed for a particular type of molecule.
Step 1:Understanding blotting techniques.
Different blotting methods detect different biomolecules:

• Southern blotting → DNA
• Northern blotting → RNA
• Western blotting → Proteins

Step 2:Principle of Southern blotting.
In Southern blotting, DNA fragments are first separated by gel electrophoresis. These fragments are then transferred onto a membrane and hybridized with a labeled DNA probe that is complementary to the target sequence.
Step 3:Detection of specific DNA sequences.
If the probe binds to the complementary DNA sequence on the membrane, the presence of the specific DNA fragment can be detected using radioactive or fluorescent signals. Therefore, the technique used to detect a specific DNA sequence is Southern blotting.