a) Where, relative to a transcriptional unit, is its promoter sequence located?

Question

a) Where, relative to a transcriptional unit, is its promoter sequence located?

b) What function is served by a promotor sequence?
c) Is the promotor sequence transcribed?

d) The promotor region of a "wild-type" prokaryotic gene includes the sequence TATAAAAAA. In vitro mutagenic procedures make it possible to subsitute a G nucleotide for the interior T nucleotide so that this section of the promoter reads TAGAAAAAA. A study comparing the transcription frequencies for the gene with the wild-type form of the promotor and the gene with the mutant promoter is undertaken in seperate but identical in vitro RNA synthesizing setups. The results indicate that the transcription rate is significatntly reduced for the gene with the mutant promoter. Based on this outcome, what conclusion can you draw regarding the functional significance of this portion of the promoter region?

Explanation / Answer

a)The promoters are the region approximately 25 to 30 bp upstream of the transcription initiation site.

b) Promoter sequences are the DNA sequences located upstream and will indicate which DNA strand will be transcribed and this strand is known as the sense strand.

c) No, the promoter sequence does not transcribe and are conserved .

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