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Home Q & A Board Biology-Related Homework Help Cell Biology
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FollowTheFez FollowTheFez
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10 years ago
Does transcription require the triphosphate precursors used for synthesis?
I can't find any information on this.


Also, is helicase used to unwind the DNA in transcription?
I thought it was but just re-reading my textbook and it says "... RNA polymerase pries the two DNA strands apart...". I think this is just a brief explanation as I'm pretty sure that polymerases can only attach to DNA strands once they've been opened. Can someone please confirm?
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#1
Educator
10 years ago
Quote from: FollowTheFez (10 years ago)
Also, is helicase used to unwind the DNA in transcription?

That's its main role.

Quote from: FollowTheFez (10 years ago)
Does transcription require the triphosphate precursors used for synthesis?
I can't find any information on this.

The triphosphate combined with nucleoside is what powers the process. The cleaving of the triphosphate into monophosphate releases enough energy for transcription to continue.
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#2
10 years ago
DNA replication starts at the origin of replication, and helicase (ONLY USED IN DNA SYNTHESIS) "unzips" or separates the 2 strands. DNA Pol III synthesizes the new DNA strand.

Transcription begins when RNA Pol II binds to promoter and starts to synthesize the new mRNA strand. Ribonucleoside triphosphate's are substrates used in RNA synthesis. The nucleotides are added one at a time to the 3' OH- group of the growing RNA molecule. 2 phosphates are cleaved from the incoming ribonucleoside triphosphate, and the remaining phosphate forms a phosphodiester bond that connects it to the growing RNA molecule. Hope that helps let me know if you need clarification.
FollowTheFez Author
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#3
10 years ago
Okay, second questions all good but I've now got two different answers with regard to Helicase!
Answer accepted by topic starter
ajc1213ajc1213
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#4
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10 years ago
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