Telomerase Key Characteristics Explained

Telomerase is a specialized enzyme crucial for maintaining the ends of eukaryotic chromosomes, known as telomeres. It functions as a reverse transcriptase, meaning it synthesizes DNA from an RNA template.

Analyzing Telomerase Statements

• Statement 1: Telomerase has 5′-3′ DNA-dependent DNA polymerisation activity.

  This is incorrect. Telomerase does not use a DNA template to synthesize DNA. Its activity relies on an internal RNA template.

• Statement 2: Telomerase has 5′-3′ RNA-dependent DNA polymerisation activity.

  This is correct. Telomerase utilizes its own integral RNA component as a template to extend the 3' end of the DNA strand in the 5′ to 3′ direction. This process is characteristic of reverse transcriptases.

• Statement 3: Telomerase contains an RNA subunit.

  This is correct. Telomerase is a ribonucleoprotein complex, meaning it is composed of both protein and RNA. The RNA subunit (TERC) is essential as it serves as the template for DNA synthesis.

• Statement 4: Telomerase has 3'-5' DNA-dependent DNA polymerisation activity.

  This is incorrect. Firstly, DNA polymerisation occurs in the 5′ to 3′ direction, not 3′ to 5′. Secondly, telomerase is RNA-dependent, not DNA-dependent.

Based on the analysis, the true statements about telomerase are that it possesses 5′–3′ RNA-dependent DNA polymerisation activity and contains an essential RNA subunit.