I am hoping that you can help me improve my understanding of transcription. :) I have tried searching for the answers to all of these questions online already, but I have either had trouble finding relevant information or I have had trouble understanding it (i.e. it was too high-level for me). I have also tried to answer my questions by browsing through different maps of genes (like this one: http://genome.ucsc.edu/cgi-bin/hgTracks?db=hg38&lastVirtModeType=default&lastVirtModeExtraState=&virtModeType=default&virtMode=0&nonVirtPosition=&position=chr9%3A132847932-133136551&hgsid=709471277_W3A9vdobj2J7obkSXshDnCBnaTeK), but my questions are still unresolved. Please note that I have come up with the following questions in my independent learning - these questions are NOT assigned homework. In all questions, I'm referring to eukaryotic (linear) DNA.

  1. Am I correct to believe that in a single chromosome, one strand of DNA is not the template strand for all genes within that chromosome? For instance, let's call one ssDNA molecule "A" and the complementary ssDNA molecule "B"; together, A and B make up a single chromosome. Am I correct to believe that in a single chromosome, the template strand for some genes will be A, and for other genes will be B?

  2. If my statement in question #1 is correct, then does that mean that multiple genes within a chromosome can be transcribed in opposite directions? Note that when I say direction, I do NOT mean 5' to 3' vs 3' to 5'. What I mean by "direction" is looking from left to right.

  3. Is it true that both strands of the double helix cannot be transcribed for a single gene in question? Is this because the promoter will only be found on one of the strands?

Thank you in advance for your time!

  • $\begingroup$ I think the fourth question ought to be separate; the question block is supposed to be for only one question, but I think the first 3 are related closely enough that they could be addressed in a single answer which deals with the underlying principle. $\endgroup$
    – rotaredom
    Feb 1, 2019 at 20:52
  • $\begingroup$ @rotaredom thank you for your feedback! I removed the 4th question. $\endgroup$
    – Anne
    Feb 1, 2019 at 21:27
  • $\begingroup$ I have answered questions 1 and 2 here and here. Your answer to your third question is right in principle, but there are cases of overlapping transcripts (promoters on different strands) as I mention here and you can find elsewhere. $\endgroup$
    – David
    Feb 1, 2019 at 23:10
  • $\begingroup$ These questions have been answered many times now. I think the closest (also with respect to the question title and body) would be, IMO, this. $\endgroup$
    Feb 5, 2019 at 14:25


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