Question

9. A study was completed comparing growth of two cell lines. These cell lines were identical except that one of them contained a loss of function mutation in the enzyme telomerase. Over many divisions, the mutant cell line's growth slowed and eventually ceased completely (resulting in earlier cell senescence). Explain this result in terms of the specific structural features of eukaryotic chromosomes that we discussed in Chapter 6. (4 pts)

Answer 1

Telomerase:

It is also known as terminal transferase (RNA dependent DNA polymerase). It is a template independent polymerase that adds species-specific telomere repeat sequences to the 3'-ends of the chromosome during replication.

Since all existing DNA polymerases can extend DNA in 5'-3' direction, in each generation, the 3'-end of the lagging strand gets shortened. This would lead to the loss of essential genes ultimately. To prevent this, telomerase enzyme adds telomeric repeat sequences at the chromosome ends.

So, a cell would eventually die if it lacks telomerase as it would lead to chromosomal loss and eventual lethality.