3. A group of students discuss on telomeres and telomerase enzyme. These are the
ID: 281509 • Letter: 3
Question
3. A group of students discuss on telomeres and telomerase enzyme. These are the questions that are being addressed. Provide the most suitable explanations. (1 mark each) (a) If a cell loses telomeres, what is the effect on the cell? (b) Compare the activity of telomerase with being active in few somatic cells and inactive in somatic cells. (c) Generally, how is the telomerase enzyme present in the somatic cells? (Whether it is active/expressed/inactive) (d) In which type of cells telomerase expressed? 4. A gene is affected such that the resultant tRNA encoded from the gene is charged with Tyr, but the anticodon that it displays is AUC. The normal alele produces a tRNA that recognizes the codon UAC, and is charged with the amino acid Tyrosine. What effect will this have on translation in these cells using affected gene for tRNA and the length of the resulting protein?(2 marks)Explanation / Answer
3
a. A telomere is a region of repetitive nucleotide sequences at the each end of a chromosome that protects the end of the chromosome from damage or fusing with the neighbouring chromosome. Telomere shortening might lead to fusion of chromosomes with each other, leading to age related breakdown of cells.When telomeres become too short, cells may not be on a position to reproduce causing the tissue to degenerate and eventually die.
b. Somatic cells where telomerase is active can synthesise back the telomeres which is responsible for slower ageing. If activity of telomerase is low in somatic cells it can lead to faster ageing, though the levels are low in somatic cells.
c.Telomerase is inactive in ost of the somatic cells though one may find a very low level of expression in them.
d. Telomerase are mainly expressed in germ cells, fetal tissue, stem cell population, activated lymphocytes and tumour cells.
4. AUC codes for Isoleucine whereas UAC codes for Tyr. Thus there will be a premature termination of protein synthesis.
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