Question

In the following partial sequence of prokaryotic DNA,

circle the consensus sequence upstream from the initiation site that facilitates the local unwinding

indicate the initiation start site with an (*)

Indicate the RNA that would be transcribed by RNA pol II (indicate 5’ and 3’ ends)

Underline the TEMPLATE strand.

3’   A G C G T T A T A C T T A T G C T C G T A A T A T C T G A AC A C 5’

5’    T C G C AA T A T G A A T A C G A G C A T T A T A G A C T TG T G   3’

Answer 1

Consensus sequence is defined as the order of most frequent residues, either nucleotides or amino acids fpund at each position in a sequence alignment. It is the optimal binding site for sequwncw dependent enzymnes like RNA Polymerase II. It is found in the protein binding site and recognize particular patterns in the promoters of the genes. Promoters are located near the transcription start site of genes, upstream on the DNA.

Consensus sequence is found in the coding or sense strand i.e. the strand with a 5'-3' orientation.

5’    T C G C AA T A T G A A T A C G A G C A T T A T A G A C T TG T G   3’

In prokaryotic DNA, the location of transcription initiation site is usually ten base pairs away from the consensus sequence. Since primers are more favourable to bind at a G or C base pair, so the initiation site of transcription in this case is marked below :

5’    T C G C AA T A T G A A T A C G A G C A T T A T A *G A C T TG T G   3’

RNA transcription occurs from the template or anti sense strand and Thymine in DNA gets converted to Uracil in RNA. Keeping these facts in mind the transcribed RNA would be :

5’ U C G C AA U A U G A A U A C G A G C A U U A U A G A C U U G U G   3’

(specified as per the RNA transcription site)

The template strand is :

3’   A G C G T T A T A C T T A T G C T C G T A A T A T C T G A AC A C 5'

(specified as per the RNA transcription site)