Telomeres are found at the ends of eukaryotic chromosomes. Why is telomerase usually active in germ-line cells but not in somatic cells?

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1. <Telomeres are repetitive nucleotide sequences at the ends of eukaryotic chromosomes that protect them from deterioration or fusion with neighboring chromosomes.>
2. <Each time a cell divides, its telomeres become shorter, which eventually leads to cell aging and death.>
3. <Telomerase is an enzyme that adds nucleotide sequences to the ends of telomeres, effectively maintaining their length and allowing cells to divide without losing important DNA sequences.>
4. <Germ-line cells, which give rise to gametes (sperm and eggs), need to maintain their telomere length to ensure genetic stability and integrity across generations. Therefore, telomerase is active in these cells.>
5. <In contrast, somatic cells (non-reproductive cells) do not typically express telomerase, leading to gradual telomere shortening and contributing to the aging process and limiting the number of times a cell can divide.>

Key Concepts

Telomeres

Telomeres are repetitive nucleotide sequences located at the ends of eukaryotic chromosomes. They protect the chromosome from deterioration and prevent fusion with neighboring chromosomes. Each time a cell divides, telomeres shorten, which is associated with aging and cellular senescence.

Telomerase

Telomerase is an enzyme that adds nucleotide sequences to the ends of telomeres, effectively extending their length. This enzyme is typically active in germ-line cells, allowing them to maintain telomere length across generations, which is crucial for reproductive success and genetic stability.

Germ-line vs. Somatic Cells

Germ-line cells are involved in reproduction and give rise to gametes, while somatic cells make up the body's tissues and organs. The activity of telomerase in germ-line cells ensures that the genetic information is preserved for future generations, whereas its limited activity in somatic cells contributes to the aging process and limits the number of times these cells can divide.