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Telomerase and Telomeres
- DNA polymerases require an available 3’ end to elongate the DNA and cannot replicate the ends of the chromosomes when the RNA primer has been removed
- Telomerase extends the 3’ end of the chromosome in structures called telomeres
- Telomeres are repetitive sequences that are complimentary to telomerases own RNA primer
- After elongation Primase can prime the extended telomere and DNA polymerase III copies the telomere and remaining 5’ end of the chromosome
- The RNA primer is removed and a single stranded region of the telomere remains
- Telomeres get shorter with each replication/division event
- Once telomeres reach a critical length the cell is signaled for apoptosis (cell death)
The ends of chromosomes are elongated by telomerase. Which of the following proteins is also involved in ensuring the inheritance of sameness at the ends of chromosomes?
i. DNA polymerase III
ii. Primase
iii. Ligase
iv. DNA polymerase I