Telomerase is an enzyme which is?

Appeared in: HPSSC Staff Nurse - 2021

Explanation

Telomerase is a complex enzyme correctly classified as a ribonucleoprotein.
It is composed of two essential parts: a protein component called telomerase reverse transcriptase (TERT) and an RNA component (TERC).
The TERC (RNA) acts as a template, and the TERT (protein) synthesizes DNA from this template to extend the chromosome ends (telomeres).
The combination of a ribonucleic acid (RNA) and a protein makes it a ribonucleoprotein.

Option A: This is incomplete. While telomerase contains a protein component (TERT), it cannot function without its integral RNA component (TERC), which serves as the template. Therefore, it is not a 'simple protein'.
Option B: This is incomplete. The RNA component (TERC) is only the template. The catalytic activity (the 'enzyme' part) comes from the protein component (TERT). An RNA molecule with catalytic activity is a ribozyme, but telomerase is a protein-RNA complex.
Option D: This describes the product of telomerase action, not the enzyme itself. Telomerase adds repetitive DNA sequences (like TTAGGG) to the ends of chromosomes, which are called telomeres.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemical composition of the enzyme telomerase as background academic context rather than a clinical decision trigger.
High telomerase activity is a hallmark of approximately 85-90% of cancer cells. This allows them to achieve 'immortality' by overcoming the normal process of telomere shortening that leads to cell death, thus enabling uncontrolled proliferation.
Inhibiting telomerase is a major strategy in cancer therapy. Drugs that target either the TERT or TERC component can cause cancer cells to age and die (senescence/apoptosis).
Conversely, mutations that impair telomerase function lead to diseases known as telomeropathies (e.g., dyskeratosis congenita), characterized by premature aging and failure of regenerative tissues like bone marrow.

How to Approach the Question

Identify the core of the question, which asks for the biochemical classification of the enzyme 'telomerase'.
This is a factual recall question from biochemistry/molecular biology.
Recall the structure of telomerase. It is known for being a reverse transcriptase that uniquely carries its own RNA template.
Analyze the term for a complex made of RNA and protein. 'Ribo' refers to ribonucleic acid, and 'protein' refers to protein. The combined term is 'ribonucleoprotein'.
Evaluate the options based on this understanding:
'Simple protein' is incorrect because it ignores the RNA part.

Concept Tested & Keywords

QOtoLf59_cZjetqGA8u9dG

E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) p. 166-168

E6 Medicine Harrison 22e Part 2 p. 1722-1724

Practise the full HPSSC Staff Nurse - 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.