bio Module 4:Set 5 — Telomeres & Telomerase

Why do linear eukaryotic chromosomes shorten during DNA replication?

Removing the final RNA primer leaves a gap at the 5′ end that DNA polymerase cannot fill.

What are telomeres?

Regions of repetitive noncoding DNA at the ends of eukaryotic chromosomes.

What is the purpose of telomeres?

To protect important genetic information from being lost when chromosomes shorten during replication.

What are telomere repeats?

Short DNA sequences repeated many times at chromosome ends.

What happens to telomeres during repeated DNA replication?

Some telomere repeats are lost, causing telomeres to shorten.

What happens when an entire telomere is lost?

Its protective buffering function fails, and important DNA may be affected.

What is telomerase?

An enzyme that extends telomeres by adding repeated DNA sequences to chromosome ends.

How does telomerase prevent chromosome shortening?

It adds telomere repeats to chromosome ends using its own RNA as a template.

What does telomerase use as a template to add DNA repeats?

An RNA sequence contained within the telomerase enzyme.

In which cells is telomerase active according to the lecture?

Rapidly dividing embryonic cells, germ cells, and cancerous somatic cells.

Why is telomerase important in rapidly dividing cells?

It helps maintain telomere length despite repeated DNA replication.

What is the main difference between telomeres and telomerase?

Telomeres are protective DNA sequences; telomerase is the enzyme that extends them.