ADNA replication
BTelomere lengthening
CDNA repair
DRNA transcription
Answer:
B. Telomere lengthening
Read Explanation:
Telomerase
The primary role of the enzyme telomerase is to maintain the length of telomeres.
Telomeres are protective caps at the ends of eukaryotic chromosomes.
They are composed of repetitive nucleotide sequences (e.g., TTAGGG in humans).
During DNA replication, a portion of the telomere is lost with each cell division because DNA polymerase cannot fully replicate the very ends of linear chromosomes. This is known as the end replication problem.
Telomerase counteracts this shortening by adding repetitive DNA sequences to the ends of the telomeres.
This enzymatic activity is crucial for preventing the loss of essential genetic information and for maintaining the stability of chromosomes.
Somatic cells (most body cells) have low or absent telomerase activity, leading to telomere shortening with age and contributing to cellular senescence.
Germ cells (sperm and egg cells), stem cells, and cancer cells typically exhibit high telomerase activity, which allows them to divide indefinitely without significant telomere shortening.
The presence of telomerase in cancer cells is a key factor in their immortality and uncontrolled proliferation.
Understanding telomerase is significant in cancer research and the development of anti-cancer therapies that aim to inhibit its activity.