What are the components and primary activity of telomerase?

• A. Telomerase is a DNA polymerase that adds repeats to ends.
• B. Telomerase is a helicase that resolves G-quadruplexes.
• C. Telomerase is a ribonucleoprotein with an RNA template and reverse transcriptase (TERT) that extends telomeres.
• D. Telomerase is an RNA helicase that unwinds telomeres.

Answer: (C)

Telomerase is a ribonucleoprotein enzyme that carries its own RNA template and a reverse transcriptase (TERT). The RNA component provides the blueprint for the telomere repeats, and the protein component uses that template to synthesize DNA, extending the 3' ends of chromosomes. This activity adds telomeric repeats (such as TTAGGG in humans) to counteract shortening during DNA replication. It’s not a standard DNA polymerase, nor a helicase, because its main role is reverse transcription guided by its RNA template to elongate telomeres.