Chapter 14, Problem 30P

Northern blot analysis is performed on cellular mRNA isolated from E. coli. The probe used in the northern blot analysis hybridizes to a portion of the lacY sequence. Below is an example of the gel from northern blot analysis for a wild $\text{-}$ type lac⁺ bacterial strain. In this gel, lane $\text{1}$ is from bacteria grown in a medium containing only glucose (minimal medium). Lane $\text{2}$ is from bacteria in a medium containing only lactose. Following the style of this diagram, draw the gel appearance for northern blots of the bacteria listed below. In each case, lane 1 is for mRNA isolated after growth in a glucose-containing (minimal) medium, and lane $\text{2}$ is for mRNA isolated after growth in a lactose-only medium.

a. Lac⁺ bacteria with the genotype ${\text{I}}^{\text{+}}{\text{ P}}^{\text{+}}{\text{ O}}^{\text{C}}{\text{ Z}}^{\text{+}}{\text{ Y}}^{\text{+}}$

b. Lac^- bacteria with the genotype ${\text{I}}^{\text{+}}{\text{ P}}^{\text{+}}{\text{ O}}^{\text{+}}{\text{ Z}}^{\text{-}}{\text{Y}}^{\text{+}}$

c. Lac^- bacteria with the genotype ${\text{I}}^{\text{+ }}{\text{P}}^{\text{-}}{\text{O}}^{\text{C}}{\text{ Z}}^{\text{+}}{\text{ Y}}^{\text{+}}$

d. Lac⁺ bacteria with the genotype ${\text{I}}^{\text{-}}{\text{P}}^{\text{+}}{\text{ O}}^{\text{C}}{\text{ Z}}^{\text{+}}{\text{ Y}}^{\text{+}}$

e. Lac^- bacteria with the genotype ${\text{I}}^{\text{+}}{\text{ P}}^{\text{+}}{\text{ O}}^{\text{+}}{\text{ Z}}^{\text{-}}{\text{Y}}^{\text{+}}$ that has a polar mutation affecting the lacZ gene

f. Lac^- bacteria with the genotype ${\text{I}}^{\text{+}}{\text{ P}}^{\text{+}}{\text{ O}}^{\text{C }}{\text{Z}}^{\text{-}}{\text{Y}}^{\text{-}}$

g. Lac^- bacteria with the genotype ${\text{I}}^{\text{+}}{\text{ P}}^{\text{+}}{\text{ O}}^{\text{+}}{\text{ Z}}^{\text{+}}{\text{ Y}}^{\text{+}}$ and a mutation that prevents CAP-cAMP binding to the CAP site.