Molecular Biology question

Question

"In E. coli, σ⁷⁰ is the major, but not the only, sigma factor. The second sigma factor to be discovered was σ³², which participates in the expression of genes involved in the heat shock response. When the environmental temperature suddenly rises, cellular production of about 20 proteins increases."

Based only on the information in the paragraph, which of the following statements can you conclude will most likely be TRUE.

 

a) Transcription of genes coding for 20 proteins probably relies on σ70 containing holoenzyme

b) Genes coding for 20 proteins have similar -10 and -35 sequences.

c) Genes coding for the 20 proteins are in an operon.

Answer 1

They likely have similar -35 and -10 sequences in their promoters. Sigma factors are the "cruise directors" of bacterial gene expression. They dictate which promoters RNA polymerase (RNAP) is directed to via sequence specific interactions between the sigma factor and the -35 and -10 promoter sequences. When conditions in or outside of the cell change, causing a different sigma factor to be produced or activated, the newly active sigma factor will direct transcription toward a set of genes that have common promoter features that match the sigma factor.

Answer 2

b) Genes coding for 20 proteins have similar -10 and -35 sequences.