In human blood cells, the length of telomeres steadily declines over time from 8,000 base pairs at birth to 3,000 base pairs as people age, and as low as 1,500 in the elderly (an entire chromosome has about 150 million base pairs). Each time a cell divides, an average person loses 30 to 200 base pairs from the ends of that cell’s telomeres.
While telomere shortening has been linked to the aging process, it is not yet known whether shorter telomeres are just a sign of aging; like gray hair, or actually contributes to aging. After conducting some research, answer the following:
• Why do cells have telomeres?
• Why do telomeres get shorter every time a cell divides? What counteracts this shortening?
• What role do telomeres play in aging? Conduct research about dyskeratosiscongenita.
• If telomerase makes cancer cells immortal, could it prevent normal cells from aging?
• Do you think we could extend the average lifespan by preserving or restoring the length of telomeres with telomerase? If so, does that raise a risk the telomerase also will cause cancer?
Address all Discussion topics.
Unit 5 Reading
• Chapter 8: “DNA: The Chemical Nature of the Gene”
• Chapter 9: “DNA Replication and Recombination”