2003 AIPMT Molecular Basis of InheritanceTranscription Unit Easy Question 170 of 200 in Molecular Basis of Inheritance

During transcription, the DNA site at which RNA polymerase binds is called : -

A Promoter
B Regulator
C Receptor
D Enhancer

The answer is A.

Solution

A transcription unit has three parts: a promoter, the structural gene and a terminator.
The promoter is a DNA sequence located towards the 5' end (upstream) of the structural gene. RNA polymerase binds here and starts transcription. It also decides which strand is the template.
In bacteria the sigma factor helps RNA polymerase recognise the promoter; in eukaryotes the TATA box is part of the promoter.
A regulator gene codes for a repressor; an enhancer increases transcription but is not the binding site of RNA polymerase.
So the DNA site at which RNA polymerase binds is called the promoter.

Concept Promoter as RNA polymerase binding site

Molecular Basis of Inheritance in past papers

200 questions from this chapter have appeared across 27 exam years.