Enabling replicative immortality
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6 Terms
What is the Hayflick limit?
- A type of cellular ageing called senescence.
- Suggests normal human cells can divide a maximum of 20-70 times.
What are telomeres?
- Protective caps on the end of chromosomes.
- Keep chromosomes from unravelling to prevent damage or attaching with other chromosomes.
- Consists of hexameric TTAGGG nucleotide repeats and shelterin.
How do telomeres cause the Hayflick limit?
- Each time a cell divides the telomere gets shorter which eventually leading to chromosome damage.
- Leads to crisis point where the cell identifies that there are damaged bits of DNA which leads to death or senescence.
What is senescence?
Biological aging - a long-term sleep for cells.
What is telomerase?
- A reverse transcriptase that adds DNA sequences onto telomeres to prevent shortening.
- Very common in tumour cells.
Why is telomerase more common in tumour cells than in healthy cells?
Tumour cells upregulate telomerase to prevent cell from dying or become senescent.
