Question

How is a mutation in a bacterial cell that deletes three base pairs 10 base pairs upstream from the +1 site likely to affect transcription and why? see section 17.1 (page 350) ?

Answer 1

The +1 site is the transcription start site and the region 10 base pairs upstream is a region of the promoter critical for sigma binding and initiation. Initiation will be inhibited because sigma cannot bind to the promoter.  Mutations are random, sudden spontaneous changes that occur in the genetic make up of an organism.