Question

Why do we extend the 3' end of the tRNA-like strand?

a) For replication initiation
b) To maintain telomere length
c) To stabilize the RNA-DNA hybrid
d) To promote DNA polymerization

Answer 1

The 3' end of a tRNA-like strand is extended to maintain telomere length during DNA replication, counteracting the inevitable shortening that happens as DNA polymerases are unable to replicate the very ends of chromosomes.

Step-by-step explanation:

The extension of the 3' end of a tRNA-like strand relates specifically to the maintenance of telomeres, which are the repetitive nucleotide sequences at the ends of eukaryotic chromosomes. This extension is necessary because DNA polymerases cannot replicate the very ends of chromosomes without a primer. Telomerase is an enzyme that adds DNA sequence repeats to the 3' end of DNA strands in the telomere regions, which compensates for the loss of DNA following replication.

In the context of DNA replication, DNA polymerase extends a DNA strand from the 3' end, working in a 5' to 3' direction. Each time a cell divides, the DNA polymerases are unable to copy the extreme ends of chromosomes, which leads to telomere shortening. However, telomerase can extend the 3' end of the chromosome, allowing DNA polymerase to fill in the complementary strand and complete replication without losing important genetic information.