The options for each are the numbers in the drop down box Human fibroblasts (ski

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The options for each are the numbers in the drop down box

Human fibroblasts (skin cells) do not normally express telomerase. After 60 cell divisions they become senescent. Fibroblasts in which telomerase has been turned on become immortal. Assuming an average telomere length of 6000 bp at birth and a minumum functional telomere length of -360 estimate the following parameters. 6,000 AGGGTT repeats at birth Nucleotides lost per cell division AGGGTT repeats at senescence Nucleotides needed to be replaced per cell division to achieve immortalit 60 10,000 6,000 1,000 600 100 60 10 6

Explanation / Answer

Telomere are the unique and distinctive sequencr present in the terminal end of eukaryoic chromosomes.The sequence consist of hexanucleotide repeats rich of Guanine(G),TTAGGG~.Telomere take part in the protection and stabilization of end site of chromosome from recombination and mutation.Ageing and cellular senescence is controled by telomere in the presence of Telomerase einzyme.The sequence in the telomere is repeated 3000 times and can repeat upto more tham 15000bp lemgth.

Telomere orrange chromosmes in the nucleous in systematic form protecting from sticking to each other,thus takes the roll of cap on the tip of chromosomes.As DNA repliation occurs in the chromosomes the length of the sequence in telomere decreases to >500 times per cel division particularly in fibroblast cells in humans.

Nucleotide lost per cell division is------------->600

According to the ament age the length of the telomere decrease.Telomere help preventing the loss of entire chromosomal gene sequence during cell division.Telomerase is not found in somatic cell and abundantly found in germ cells like skin cells.Hence somatic cells shows ageing and germ cells doesn't age.

Nucleotide needed to be replaced per cell division to acgieve immortality is 100 is which commonly found in cancerous cells. In cancerous cells the gene arrangemnt in chromosomes are disturbed and results in regaining of the lost sequence leading to immortal characteristcs.

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