Which of the following types of cells are affected most by telomere shortening?

• A. Germ cells
• B. Stem cells
• C. Cancer cells
• D. Somatic cells

Answer: (D)

Verified step by step guidance

1. Understand the concept of telomeres: Telomeres are repetitive DNA sequences at the ends of chromosomes that protect them from damage during cell division. Each time a cell divides, telomeres shorten, eventually leading to cell aging or apoptosis when they become critically short.
2. Identify the types of cells listed in the problem: Germ cells, stem cells, cancer cells, and somatic cells. Each type has different mechanisms for maintaining telomere length or dealing with telomere shortening.
3. Analyze the role of telomerase: Telomerase is an enzyme that adds DNA sequences to telomeres, preventing their shortening. Germ cells, stem cells, and cancer cells typically express telomerase, allowing them to maintain telomere length and divide indefinitely.
4. Focus on somatic cells: Somatic cells (non-reproductive body cells) generally do not express telomerase. As a result, their telomeres shorten with each division, making them more susceptible to the effects of telomere shortening, such as aging and loss of function.
5. Conclude that somatic cells are most affected by telomere shortening because they lack the mechanisms to maintain telomere length, unlike germ cells, stem cells, and cancer cells.