Question

question 2 (1 point) ✓ saved
which statement explains the relationship between telomere shortening and cancer cell proliferation?
cancer cells proliferate indefinitely because they do not have telomeres.
cancer cells can reproduce limitlessly because they do not undergo telomere shortening.
cancer cells lack the enzyme telomerase, so they do not undergo telomere shortening.
cancer cells grow uncontrollably because of accelerated telomere shortening.
cancer cells grow uncontrollably because they have mutations that block telomere formation.

Explanation:

Telomeres are protective caps at the ends of chromosomes. In normal cells, telomeres shorten with each cell division, eventually leading to cell senescence (aging) or apoptosis (programmed cell death). Cancer cells, however, often have mechanisms to maintain telomere length. One such mechanism is the activation of the enzyme telomerase, which can add DNA sequences to telomeres, preventing their shortening. This allows cancer cells to divide indefinitely (proliferate limitlessly) without undergoing the normal constraints imposed by telomere shortening.

Let's analyze each option:

• Option 1: Cancer cells do have telomeres. This statement is incorrect.
• Option 2: Cancer cells can reproduce limitlessly because they can prevent telomere shortening (often via telomerase activation). This is a correct statement.
• Option 3: Cancer cells often have telomerase (or other mechanisms) to prevent telomere shortening. Saying they lack telomerase is incorrect for most cancer cells.
• Option 4: Accelerated telomere shortening would lead to cell death, not uncontrolled growth. This is incorrect.
• Option 5: Cancer cells don't block telomere formation; they maintain or elongate telomeres. This is incorrect.

Answer:

B. Cancer cells can reproduce limitlessly because they do not undergo telomere shortening.