Question

Reverse transcriptase enzymes is used in

• A. mRNA Synthesis
• B. tRNA Synthesis
• C. cDNA Synthesis
• D. Vector synthesis

Hint:

cDNA synthesis is a critical step in RT-PCR (Reverse Transcription Polymerase Chain Reaction) and RNA-Seq, which are used to detect and quantify gene expression levels in research and clinical diagnostics.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
According to the central dogma of molecular biology, genetic information flows from DNA to RNA to protein.
However, retroviruses contain the enzyme reverse transcriptase, which can reverse this flow by synthesizing DNA using an RNA template.

Step 2: Detailed Explanation:
Reverse transcriptase (RNA-dependent DNA polymerase) is an enzyme originally isolated from retroviruses.
In molecular biology, this enzyme is used to synthesize complementary DNA (cDNA) using a messenger RNA (mRNA) template.
The process involves:
1. Annealing a primer (such as an oligo-dT primer that binds to the poly-A tail of eukaryotic mRNA) to the template RNA.
2. Using reverse transcriptase to synthesize a complementary single-stranded DNA chain alongside the RNA template, forming an RNA-DNA hybrid.
3. Degrading the RNA strand using RNase H and using DNA polymerase to synthesize the second DNA strand, producing a double-stranded cDNA molecule.
This cDNA lacks the introns present in genomic DNA, allowing eukaryotic genes to be expressed in prokaryotic host systems.
The other options are incorrect: mRNA and tRNA are synthesized by cellular RNA polymerases, and vector synthesis involves recombinant DNA assembly using restriction enzymes and ligases.

Step 3: Final Answer:
The reverse transcriptase enzyme is used in cDNA synthesis, corresponding to option (C).