What is the primary function of telomerase enzyme?

Question

What is the primary function of telomerase enzyme?

1. A. DNA replication
2. B. Telomere lengthening (Correct answer)
3. C. DNA repair
4. D. RNA transcription

Correct Answer

Option B — Telomere lengthening

Detailed Solution & Explanation

The correct answer is Telomere lengthening.

Key Points

• Telomeres are repetitive DNA sequences capping the ends of chromosomes, protecting them from degradation and from fusing with one another.
• Each round of DNA replication leaves the ends slightly shorter, because DNA polymerase cannot fully copy the lagging strand's terminus — the "end replication problem".
• Telomerase counteracts this by adding repeat sequences back onto the telomeres, extending them.

Additional Information

• Telomerase is a reverse transcriptase, carrying its own RNA template — unusual among human enzymes.
• It is largely inactive in most adult somatic cells, so telomeres shorten with each division until the cell stops dividing, a process linked to cellular ageing (senescence).
• It is highly active in stem cells, germ cells and around 85-90% of cancer cells, where it enables unlimited division — making it a target for cancer research.
• Elizabeth Blackburn, Carol Greider and Jack Szostak shared the 2009 Nobel Prize in Physiology or Medicine for discovering how telomeres and telomerase protect chromosomes.

प्रश्न (हिन्दी में)

टेलीमेरेज़ एंजाइम का प्राथमिक कार्य क्या है?

1. A. डीएनए प्रतिकृति
2. B. टेलीमेरे का लंबा होना
3. C. डीएनए की मरम्मत
4. D. आरएनए प्रतिलेखन