Suppose that a human zygote begins life with 1500 telomere r

Suppose that a human zygote begins life with 1500 telomere repeats. Most somatic cells lose telomeres at every mitotic cell division. Further suppose that a cell begins to lose essential genes (non-telomere sequences) from its ends after 50 cell generations.

How many cells are produced from one precursor cell after 50 cell generations? On average, how many telomeres are lost at each mitosis?

Explain why telomeres are lost in the context of the question.

Solution

Number of cells produced from one precursor cell after 50 generations = 1500 /50 = 30

Number of telomeres are lost at each mitosis = 30 / 50 = 0.6

Telomere is the end regions of chromosome that caps and protects the DNA sequences. Telomere is repetitive nucleotide sequence generally containing TTAGGG nucleotides. During replication some of DNA sequences are not replicated and are lost. Telomere prevents this loss by capping the chromosomes. The sequences of telomeres are replicated by telomerase enzyme. The telomerase locks the sequences and inhibits the cell division in cancerous cells. Therefore, telomerase plays an important role in DNA metabolism and cell cycle regulation. Thus, Chromosomes that do not express telomerase may not undergo proper replication or may lose control over cell cycle and over expressed resulting in cancerous growth of cells. The cells that are lacking telomerase lost the telomeres.