Question

Which of the following molecular marker techniques is used for identifying genetic variation based on differences in DNA fragment sizes?

• A. RFLP
• B. RAPD
• C. AFLP
• D. SSR

Hint:

RFLP stands for Restriction Fragment Length Polymorphism. It identifies genetic variation by analyzing the different lengths (sizes) of DNA fragments generated by restriction enzyme digestion.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Molecular markers are tools used to identify genetic variation among individuals.
Many classic molecular marker techniques identify polymorphisms based on differences in the sizes of DNA fragments, which are separated and visualized using gel electrophoresis.

Step 2: Detailed Explanation:
Let us analyze the listed molecular marker techniques:
- RFLP (Restriction Fragment Length Polymorphism): This is a hybridization-based, non-PCR marker.
In this technique, genomic DNA is digested with specific restriction enzymes.
Mutations (such as single nucleotide polymorphisms or indels) within the restriction sites or the region between them alter the length of the resulting fragments.
These differences in DNA fragment sizes are detected by Southern hybridization using a labeled probe.
The name "Restriction Fragment Length Polymorphism" directly reflects the identification of genetic variation based on fragment size (length) differences.
- RAPD, AFLP, and SSR: These are PCR-based marker techniques that also detect variation based on fragment size differences on gels.
However, RFLP is the classical, pioneer technique designed specifically around identifying restriction fragment size variations.
Therefore, RFLP is the standard representative marker for size-based restriction fragment polymorphisms.

Step 3: Final Answer:
Hence, the correct option is (A).