One striking difference at the level in which transcription is initiated between
ID: 149180 • Letter: O
Question
One striking difference at the level in which transcription is initiated between prokaryotes and eukaryotes is that in prokaryotes transcription runs in the 3'-5 direction, whereas in eukaryotes it runs in the 5-3 direction" "in prokaryotes many protein factors other than the polymerase are needed to ensure processive transcription, whereas in eukaryotes once transcription is started the RNA-Pol is enough "in prokaryotes all factors required to start transcription are associated to the holo-enzyme, whereas in eukaryotes additional protein factors besides the RNA-Pol are needed to initiate transcription in prokaryotes the DNA is already accessible whereas in eukaryotes the DNA must first be turned into heterochromatin before being transcribed "in prokaryotes transcription does not require energy, whereas in eukaryotes a substantial amount of energy is required to start transcription 'in prokaryotes no helicase activity is required to open up the double-stranded DNA template, whereas in eukaryotes a helicase is required to start transcription"Explanation / Answer
In this question option ' C ' is correct .
In prokaryotes only one type of RNA polymerase is present
which synthesise all type of RNA ( t RNA , m RNA, r RNA) in the cell.
This RNA polymerase have 5 subunits ( 2 alpha , 2 beta and one omega subunit).
In prokaryotes sigma factor is present which is essential for transcription initiation.
While in the Eukaryotes -
Eukaryotes have three types of RNA polymerase in the cell.
RNA polymerase | for rRNA synthesis , RNA polymerase || for mRNA synthesis .
RNA polymerase||| for the synthesis of tRNA and 5S rRNA .
RNA polymerase | have 14 subunits ,RNA polymerase || have 10-12 subunits and RNA polymerase||| have 12 subunits.
In Eukaryotes sigma factor is absent and it is not necessary for transcription. Initiation of transcription is facilitated by initiation factor.
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