Transcription, RNA Processing and Translation Exercise A: Transcription in Proka

Question

Transcription, RNA Processing and Translation Exercise A: Transcription in Prokaryotes (con't) Initiation of transcription: removal of sigma Once a few ribonucleotides are synthesized by RNA Polymerase, the sigma protein is removed. Once the sigma is removed, it can be reused to initiate transcription (Fig 5) Fig. 5. Initiation of transcription, removal of the sigma. Elongation of transcription After the sigma is removed, RNA Polymerase continues to unzip template and coding strands of the the DNA, and R-nucleotides are bonded via phosphodiester linkages using the code provided by the template strand of DNA (Fig. 6). The incoming DNA enters into an intake portal and is unzipped by a zipper As the DNA passes the zipper, the strand and the DNA double helix leaves through an exit portal, R-nucleotides entec in through another intake portal and are combined via complementary base pairing to the template strand of DNA The R-nucleotides are bonded together via phosphodiester linkages. R nucleotides are continuously added to the 3'end of the developing RNA strand. The 5' end of the RNA strand leaves through another exit portal of the RNA Polymerase, 7. What is this structure? 8. Which end of the RNA emerges from the exit portal of RNA Polymerase? Fig. 6. Elongation of transcription wwthehileyerimer.com

Explanation / Answer

During the transcription process second stage is the elongation phase.Ribonucleotide sequence will be added one after another to produce the long chain of RNA molecule.That RNA will be called as messanger RNA because they carry all the codons which will ultimately code for other proteins.Template DNA strand acts as a template to produce the RNA.Elongation process is always from 5 prime to 3 prime direction of the newly synthesized RNA.One single nucleotide is added each time as this polymerase goes.Protein bridge is a type of protein subunit which associates with RNA polymerase during the transcription in the elongation phase which ensures providing of the template nucleotide as well as proper binding of the newly nucleotide sequence.Protein bridge attached with DNA and allow only one nucleotide as a sequence from the DNA template to be free to react.The 3 prime hydroxyl is free for the chain elongation.Once one nucleotide is added protein bridge slightly dissociate and shifts one nucleotide apart.Protein bridge ensures to provide one nucleotide at a time from the DNA template to interact with the ribonucleotide these sequences will be added to the growing chain and they finally produce RNA strand.This process will occur from the 5 prime of the RNA to the 3 prime of RNA.

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