Question

Which of the following statements about telomerase are true:

1. It extends the 3' end of a linear chromosome one repeat at a time.
2. It uses a built-in DNA to act as a template for synthesis of the telomeric repeat.
3. Without telomerase, linear chromosomes would become progressively shorter.

Answer 1

All given statements about telomerase are true: It extends the 3' end of linear chromosomes one repeat at a time, uses its built-in RNA as a template for synthesizing telomeric repeats, and prevents linear chromosomes from becoming progressively shorter.

Step-by-step explanation:

The student's question about telomerase involves determining the validity of several statements about this crucial enzyme that extends telomeres. Here are the points with explanations:

1. Telomerase extends the 3' end of a linear chromosome one repeat at a time. This is true. Telomerase adds short, repeated sequences of DNA to the 3' end of telomeres, compensating for the shortening that occurs during DNA replication.
2. Telomerase uses a built-in RNA to act as a template for synthesis of the telomeric repeat. This is also true. The enzyme includes an RNA component that serves as a template for adding telomere repeats to the end of the chromosome.
3. Without telomerase, linear chromosomes would become progressively shorter. This is a true statement as well. Each time a cell divides, the DNA replication machinery cannot fully replicate the very ends of chromosomes, leading to progressive shortening unless telomerase is present to extend the telomeres.

Elizabeth Blackburn, along with her colleagues, won the Nobel Prize for the discovery of telomerase. In humans, the telomerase enzyme is typically active in germ cells and adult stem cells and is associated with preventing the aging of these cells by maintaining the integrity of telomeres.