Podcast
Questions and Answers
What is the primary function of telomeres?
What is the primary function of telomeres?
How do telomeres relate to the aging process?
How do telomeres relate to the aging process?
Which sequence best describes telomeric DNA in humans?
Which sequence best describes telomeric DNA in humans?
What occurs to telomeres in normal somatic cells after multiple divisions?
What occurs to telomeres in normal somatic cells after multiple divisions?
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What is the role of telomerase in stem cells and cancer cells?
What is the role of telomerase in stem cells and cancer cells?
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What does the end replication problem primarily affect?
What does the end replication problem primarily affect?
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What is the structural characteristic of telomeres?
What is the structural characteristic of telomeres?
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What components make up the telomerase enzyme?
What components make up the telomerase enzyme?
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Study Notes
Telomeres
- Telomeres are protective caps at the ends of linear chromosomes, composed of non-coding DNA and proteins
- They act like mitotic clocks – their length inversely correlates with cell divisions
- Telomeres prevent chromosome degradation by nucleases
- They allow repair systems to distinguish chromosome ends from DNA breaks
### Telomere Structure
- Human telomeric DNA is made up of multiple repeats of the hexameric sequence AG3T2
- This sequence is base-paired to a complementary region of Cs and As
- The GT-rich strand is longer than the CA complement, leaving a single-stranded region of a few hundred nucleotides
- This single-stranded region forms a loop structure stabilized by protein
### End Replication Problem
- Replicating linear DNA ends poses a challenge in eukaryotic cells
- Removal of the RNA primer from the 5’ end leaves a gap that cannot be filled
- As cells divide, telomeres progressively shorten
- Shortened telomeres contribute to cellular senescence (cell aging)
Telomerase and Telomere Maintenance
- Germ cells, stem cells, and cancer cells maintain telomere length through the action of telomerase
- Telomerase is a ribonucleoprotein containing a reverse transcriptase protein and a template RNA
- The RNA template base-pairs with the GT-rich single-stranded 3' end of telomeric DNA, allowing telomere extension
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Description
This quiz delves into the fascinating world of telomeres, the protective caps at the ends of chromosomes. Explore their structure, function, and the end replication problem that leads to cellular aging. Test your knowledge on how telomeres contribute to genomic stability.
