The GATE Grind

GATE 2022 BT – Question 26

Recombinant DNA Technology and Other Tools in Biotechnology · Molecular tools: PCR, DNA and RNA labelling, Sanger and next generation sequencing, Southern and northern blotting, in-situ hybridization, DNA fingerprinting · 1 mark · Multiple choice

Among individuals in a human population, minor variations exist in nucleotide sequences of chromosomes. These variations can lead to gain or loss of sites for specific restriction enzymes. Which of the following technique is used to identify such variations?

  1. Polymerase dependent fragment insertion
  2. Real-time polymerase chain reaction
  3. Restriction fragment length polymorphism
  4. Reverse transcriptase polymerase chain reaction

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) Restriction fragment length polymorphism

Explanation

The question describes variations in the DNA sequence that **create or destroy a restriction site**. When the DNA of different individuals is cut with the same enzyme, the **length of the fragments** differs.

This is the principle of **Restriction Fragment Length Polymorphism (RFLP)**: the DNA is digested, the fragments are separated by gel electrophoresis, and a probe (Southern blot) or PCR is used to see the pattern.

The other techniques do not assay this: real-time PCR quantifies DNA, RT-PCR amplifies RNA, and "polymerase dependent fragment insertion" is not a standard technique.

Answer **RFLP** (C).