Question

Select the option which correctly tells the position of components in the transcription unit.

• A. Terminator – located towards 5’ end of coding strand of gene
• B. Operator - located towards 3’ end of coding strand of gene
• C. Promoter – located towards 3’ end of coding strand of gene
• D. Promoter – located towards 5’ end of coding strand of gene

Answer 1

The correct option is D Promoter – located towards 5’ end of coding strand of gene

Location of promoter gene and terminator gene is always mentioned with reference to the coding strand.

Promoter is located upstream (to the left) of the structural gene, i.e., towards the 5' end of coding strand, 3' end of template strand.

Terminator – It is the region of DNA that is present at the 3' end of the coding strand.

Operator genes contain the codes necessary to begin the process of transcribing DNA messages of one or more structural genes into mRNA. Structural genes are linked to the operator gene in a functional unit called an operon.