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DKC(Dyskeratosis congenital) is a genetically inherited disease....proliferate capacity of stem cells is markedly impaired.The defect has been traced to inadequate production of an ezyme needed for Chromosome duplication in the nuclei of rapidly dividing cells.
Structural analysis shows the active site of this protein contains a SS-RNA that is required for normal catalytic function.Which step in DNA replication is most likely deficient in DKC patients?
A.syntesis of Centromeres
B.synthesis of Okasaki fragments
C.synthesis of RNA primers
D.Synthesis of telomeres
D.Removal of RNA primers
Please explain your answer . Thank you.
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DD . Telomerase contain a RNA segment and has reverse trascriptase activity that adds telomeres after each cycle of cell division.
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C.,Since the other strand is lacking ,Synthesis of telomeres is impaired?
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D. Synthesis of telomeres.
telomerase activity is an integral part of rapidly dividing cells like stem cells as it "imortalizes" them. When the telomerase activity is lost, the stem cells become stable or permanent cells ( similar to the DKC condition). Telomerase synthesizes terminal DNA fragments of the chromosome thru its Reverse Transcriptase activity using its intrinsic RNA as a template
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The answer is D...Synthesis of telomeres
Thank you img87,chyme
This enzyme is Telomerase,a revrerse transcriptase ,that replicates the ends(telomeres) of linear chromosomes.
Telomerase...is an enzyme in eukaryots used to maintain the telomers.it contains a short RNA templete complementary to the DNA telomere sequence,as well as telomerase reverse transcriptase activity(hTRT).It is able to replace the telomere sequences that would otherwise be lost during replication.
Normally Telomerase is present only in embeyonic cells,germ(reproductive)cells, and stem cells,but not in somatic cells.
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It is really a good question,maryam thanks a lot.samideb
