Question

In which of the following molecular markers, polymerase chain reaction (PCR) is required?
A. Restriction Fragment Length Polymorphism (RFLP)
B. Random Amplified Polymorphic DNAs (RAPD)
C. Amplified Fragment Length Polymorphism (AFLP)
D. Sequence-Tagged Sites (STSs)
Choose the correct answer from the options given below:

• A. A, B and C only
• B. A, C and D only
• C. A, B, C, D
• D. B, C and D only

Hint:

A quick way to solve this is to look for the word "Amplified" in the name of the marker (like in RAPD and AFLP), which is a direct giveaway that PCR is involved. For others, remember that RFLP is the classic, non-PCR hybridization-based method.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The question asks to identify which of the listed molecular marker techniques rely on the Polymerase Chain Reaction (PCR) as a core part of their methodology. PCR is a technique used to amplify specific segments of DNA.
Step 2: Detailed Explanation:
Let's examine each marker technique:

A. Restriction Fragment Length Polymorphism (RFLP): This is a non-PCR based technique. It involves cutting genomic DNA with restriction enzymes, separating the resulting fragments by gel electrophoresis, and then using a labeled probe to detect specific fragments via Southern blotting. No amplification step is involved.

B. Random Amplified Polymorphic DNAs (RAPD): The name itself says "Amplified". This technique uses short, arbitrary primers to amplify random segments of the genomic DNA using PCR. The presence or absence of amplified bands indicates polymorphism. PCR is essential.

C. Amplified Fragment Length Polymorphism (AFLP): This technique also has "Amplified" in its name. It is a multi-step process that begins with restriction digestion of DNA, followed by ligation of specific adapters, and then selective PCR amplification of a subset of these fragments. PCR is essential.

D. Sequence-Tagged Sites (STSs): An STS is a short, unique sequence in a genome. Its presence within a DNA sample is detected by designing specific primers for that sequence and performing a PCR assay. A successful amplification (producing a band of the expected size) confirms the presence of the STS. PCR is essential.

Step 3: Final Answer:
Based on the analysis, RAPD, AFLP, and STS are all PCR-based techniques, while RFLP is not. Therefore, the correct group is B, C, and D.