when is telomerase enzyme essential?

Answer 1

Telomerase is important for replicating the ENDS of DNA. Think of how Okazaki fragments work. During replication, the DNA Polymerase complex needs to bind to DNA to initiate replication, and in the lagging strand (where okazaki fragments are used to replicate the DNA), since you would be at the end of the DNA molecule, there would be nothing for the enzymes to "LATCH" on to. The DNA replication enzymes use TELOMERES to latch on to, to begin okazaki fragment replication. Telomerase is the enzyme that adds this DNA to make the telomeres on the ends of the chromosomes.

Now, why is this significant? Telomeres are incredibly important in the cell cycle, and each turn of the cell cycle their length is shortened. (Whenever you see cell cycle, two words should jump into your mind, aging, but more importantly, CANCER). What does this do? Well, if there are no telomeres, DNA will not be relpicated, so shortened DNA leads to increased AGING. If the telomeres are OVERexpressed, that leads to cancer.