Replication: A. Why is a reverse transcriptase (telomerase) necessary to extend
ID: 1070123 • Letter: R
Question
Replication:
A. Why is a reverse transcriptase (telomerase) necessary to extend the telomere 3' end of the chromosome insted of a DNA polymerase?
B. which of the polymarse that are used to replicate the rest of the (non-telomere) genome are used to complate the synthesis of the telmore (i.e. the strand that is complementry to the telomere 3' strand) ?
C. Which of the replication enzymes that are used to replicate the rest of the (non-telomere) genome are NOT NEEDED to complate the strand that is complementry to the telmere 3' strand?
Explanation / Answer
A. Why is a reverse transcriptase (telomerase) necessary to extend the telomere 3' end of the chromosome insted of a DNA polymerase?
Telomerase is a ribonucleoprotein selected to imitate finishes of direct chromosomes since ordinary DNA polymerase can't repeat the closures, or telomere. The single-strand 3' shade of the twofold strand chromosome with the arrangement 5'- TTAGGG-3' initiates telomerase.
Telomerase acts like other DNA polymerases by broadening the 3' end, in any case, dissimilar to other DNA polymerases, telomerase does not require a format. The TERT subunit, a case of a switch transcriptase, utilizes the RNA subunit to shape the primer–template intersection that permits telomerase to expand the 3' end of chromosome closures. The progressive lessening in size of telomeres as the aftereffect of numerous replications over a lifetime are thought to be connected with the impacts of maturing
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B. which of the polymarse that are used to replicate the rest of the (non-telomere) genome are used to complate the synthesis of the telmore (i.e. the strand that is complementry to the telomere 3' strand)
As DNA polymerase alone can't reproduce the finishes of chromosomes, telomerase helps in their replication and forestalls chromosome debasement.
Straight chromosomes have an end issue. After DNA replication, each recently orchestrated DNA strand is shorter at its 5' end than at the parental DNA strand's 5' end. This delivers a 3' overhang toward one side (and one end just) of every little girl DNA strand, with the end goal that the two girl DNAs have their 3' overhangs at inverse finishes
Each RNA groundwork integrated amid replication can be expelled and supplanted with DNA strands aside from the RNA preliminary at the 5' end of the recently orchestrated strand. This little area of RNA must be evacuated, not supplanted with DNA. Chemicals RNase H and FEN1 expel RNA preliminaries, however DNA Polymerase will include new DNA just if the DNA Polymerase has a current strand 5' to it ("behind" it) to develop. Be that as it may, there is no more DNA in the 5' bearing after the last RNA groundwork, so DNA polymerse can't supplant the RNA with DNA. Along these lines, both little girl DNA strands have a deficient 5' strand with 3' overhang.
Without extra cell forms, nucleases would process these single-stranded 3' overhangs. Every little girl DNA would get to be distinctly shorter than the parental DNA, and in the long run whole DNA would be lost. To keep this shortening, the finishes of direct eukaryotic chromosomes have uncommon structures called telomeres.
Telomere Replication
The closures of the straight chromosomes are known as telomeres: tedious groupings that code for no specific quality. These telomeres shield the vital qualities from being erased as cells partition and as DNA strands abbreviate amid replication.
In people, a six base combine grouping, TTAGGG, is rehashed 100 to 1000 circumstances. After each round of DNA replication, some telomeric arrangements are lost at the 5' end of the recently orchestrated strand on every little girl DNA, but since these are noncoding successions, their misfortune does not antagonistically influence the phone. Be that as it may, even these arrangements are not boundless. After adequate rounds of replication, all the telomeric rehashes are lost, and the DNA dangers losing coding arrangements with resulting rounds.
The disclosure of the compound telomerase helped in the comprehension of how chromosome finishes are kept up. The telomerase catalyst appends to the end of a chromosome and contains a synergist part and an inherent RNA format. Telomerase adds correlative RNA bases to the 3' end of the DNA strand. Once the 3' end of the slacking strand format is adequately prolonged, DNA polymerase adds the integral nucleotides to the finishes of the chromosomes; along these lines, the closures of the chromosomes are recreated.
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. Which of the replication enzymes that are used to replicate the rest of the (non-telomere) genome are NOT NEEDED to complate the strand that is complementry to the telmere 3' strand?
Helicase
Utilizes the hydrolysis of ATP to "unfasten" or loosen up the DNA helix at the replication fork to permit the subsequent single strands to be duplicated.
Primase
Polymerises nucleotide triphosphates in a 5' to 3' heading. The compound incorporates RNA preliminaries to go about as a format for future Okazaki sections to expand on to.
DNA Polymerase III
Accountable for integrating nucleotides onto the main end in the great 5' to 3' course.
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DNA Polymerase I
Accountable for integrating nucleotides onto introductions on the slacking strand, shaping Okazaki pieces. In any case, this protein can't totally blend the greater part of the nucleotides.
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Ligase
This protein is accountable for "sticking" together Okazaki parts, a range that DNA Pol I can't blend.
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Telomerase
Catalyzes the extending of telomeres; the catalyst incorporates a particle of RNA that serves as a format for new telomere fragments.
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Nuclease
This protein is accountable for extracting, or removing, undesirable or inadequate fragments of nucleotides in a DNA succession.
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Topoisomerase
This protein presents a solitary strand scratch in the DNA, empowering it to swivel and along these lines soothe the aggregated winding strain produced amid loosening up of the twofold helix.
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Single Strand Binding Proteins
In charge of holding the replication fork of DNA open while polymerases read the formats and plan for union.