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DNA transcription

As I understand the DNA strand is read 3' to 5' during transcription. Why then is the promoter region at the 5' end? surely it should be at the 3' end? Thanks
Original post by jsmith6131
As I understand the DNA strand is read 3' to 5' during transcription. Why then is the promoter region at the 5' end? surely it should be at the 3' end? Thanks


On a basic level, the promoter is a nucelotide sequence which is present on the coding strand upstream of the gene (e.g. the pribnow box in prokaryotes). Now this would have a complementary nucleotide sequence on the template strand as well. We can categorize the promoter activity as follows: The consensus nucelotide sequence tagged as the promoter (e.g. TATAAT) will be present on the coding strand upstream of the coding gene, but the promoter activity will be due to complement sequence present on the template strand.

Moreover, the promoter sequence on the coding strand is where the sigma factor binds with, after it has been complexed to form the holoenzyme RNA polymerase.

I hope this helps :smile:
Original post by Dynamo123
On a basic level, the promoter is a nucelotide sequence which is present on the coding strand upstream of the gene (e.g. the pribnow box in prokaryotes). Now this would have a complementary nucleotide sequence on the template strand as well. We can categorize the promoter activity as follows: The consensus nucelotide sequence tagged as the promoter (e.g. TATAAT) will be present on the coding strand upstream of the coding gene, but the promoter activity will be due to complement sequence present on the template strand.

Moreover, the promoter sequence on the coding strand is where the sigma factor binds with, after it has been complexed to form the holoenzyme RNA polymerase.

I hope this helps :smile:


I see....thanks

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