Question

The enzyme reverse transcriptase is for

• A. Killing the virus
• B. Avoiding the virus infection
• C. Making cDNA from RNA
• D. Making RNA from DNA

Hint:

Reverse Transcription = RNA $\rightarrow$ DNA.
Standard Transcription = DNA $\rightarrow$ RNA.
The "c" in cDNA stands for "Complementary." cDNA is essential because it lacks introns and can be directly expressed in prokaryotic systems.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the specific function of the enzyme reverse transcriptase in the context of molecular biology and biotechnology.
Detailed Explanation:

• Central Dogma Reversal:
The standard "Central Dogma" of molecular biology is $DNA \rightarrow RNA \rightarrow Protein$.
Certain viruses (retroviruses like HIV) have an RNA genome and use the enzyme reverse transcriptase to copy their RNA into DNA once they enter a host cell.

• Mechanism of Reverse Transcriptase:
The enzyme is an RNA-dependent DNA polymerase.
It uses a single-stranded RNA template to synthesize a complementary DNA (cDNA) strand.

• Applications in Biotechnology:
RT-PCR: Used to detect RNA viruses (like COVID-19) by first converting the viral RNA to DNA so it can be amplified.
cDNA Library Construction: Since eukaryotic genomic DNA contains introns (non-coding regions), scientists use reverse transcriptase to turn mature mRNA (which only contains coding exons) into cDNA. This cDNA can then be inserted into bacteria to produce eukaryotic proteins like insulin.

Step 2: Final Answer:
The enzyme reverse transcriptase is used to synthesize complementary DNA (cDNA) using an RNA template.