jimmy432
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I always thought it is the transcription factor that binds to the RNA polymerase to form the transcription-initiation complex which then binds to the promoter region on the template (antisense) strand of the DNA of the gene being coded for. Then the gene is transcribed to produce mRNA.

However, in a mark scheme it says:
1 - transcription factor binds to promoter region
2 - RNA polymerase binds (I presume it binds to the transcription factor?)
3 - mRNA is synthesised

So, is it the transcription factor which binds to RNA polymerase to form the transcription-initiation complex to then bind to promoter region or does the transcription factor bind straight to the promoter region then the RNA polymerase comes along and binds to the transcription factor to form the transcription-initiation complex?
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bobby147
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(Original post by jimmy432)
I always thought it is the transcription factor that binds to the RNA polymerase to form the transcription-initiation complex which then binds to the promoter region on the template (antisense) strand of the DNA of the gene being coded for. Then the gene is transcribed to produce mRNA.

However, in a mark scheme it says:
1 - transcription factor binds to promoter region
2 - RNA polymerase binds (I presume it binds to the transcription factor?)
3 - mRNA is synthesised

So, is it the transcription factor which binds to RNA polymerase to form the transcription-initiation complex to then bind to promoter region or does the transcription factor bind straight to the promoter region then the RNA polymerase comes along and binds to the transcription factor to form the transcription-initiation complex?
The first one you are describing is true for bacteria .The one the mark scheme is describing is for Eukaryotes,but at A-level,the distinction is not made ,which leads to confusion.
In bacteria,RNA polymerase binds to the transcription factor and can then bind to the promoter region.
In Eukaryotes,you have multiple transcription factors that bind to the promoter region.RNA polymerase then binds to form a transcription iniation complex,which then transcribe DNA.

Basically,without the transcription factors,RNA polymerase won't bind tightly to the promoter region.This is important because with out the promoter,RNA polymerase kind of slides off the DNA and does not stay on it for very long.
Bacteria have a different RNA polymerase to Eukaryotes.They also use different transcription factors. This is what accounts for the difference mainly.
Hope this helps .
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bobby147
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My advice btw would be to stick with the mark scheme answer,since that is what will get you the marks.
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