Question

Telomerase acts as a cellular reverse transcriptase that provides the active site for:

• A. RNA-dependent DNA synthesis
• B. DNA-dependent RNA synthesis
• C. RNA-dependent RNA synthesis
• D. DNA-dependent DNA synthesis

Hint:

Remember the enzyme naming convention: The first part describes the template, and the second part describes the product being synthesized. "RNA-dependent DNA synthesis" means "uses RNA as a template to synthesize DNA." This is the definition of reverse transcription, the function of telomerase.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Telomerase is a ribonucleoprotein enzyme responsible for maintaining the length of telomeres, which are the protective caps at the ends of eukaryotic chromosomes.
It prevents the progressive shortening of chromosomes that occurs during standard DNA replication.
The term "reverse transcriptase" refers to an enzyme that synthesizes DNA from an RNA template.
Step 2: Detailed Explanation:
Let's break down the function of telomerase:


Telomerase contains its own built-in RNA molecule that serves as a template.

It uses this RNA template to synthesize DNA, adding repetitive nucleotide sequences to the 3' end of the DNA strand.

The process of synthesizing DNA using an RNA template is called RNA-dependent DNA synthesis.

Let's analyze the other options:


DNA-dependent RNA synthesis is transcription, carried out by RNA polymerase.

RNA-dependent RNA synthesis is carried out by RNA replicase, found in some RNA viruses.

DNA-dependent DNA synthesis is standard DNA replication, carried out by DNA polymerase.

Step 3: Final Answer:
Since telomerase is a reverse transcriptase that uses an RNA template to synthesize DNA, its activity is RNA-dependent DNA synthesis.