Northern blot analysis is performed on cellular mRNA iso...

Question

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-type lac⁺ bacterial strain. In this gel, lane 1 is from bacteria grown in a medium containing only glucose (minimal medium). Lane 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 2 is for mRNA isolated after growth in a lactose-only medium.

lac⁻ bacteria with the genotype I⁺ P⁺ Oᶜ Z⁻ Y⁻

Accepted Answer

Welcome back, everyone. Here's your next question. Suppose that you are performing a northern blot analysis to study the expression of the LAC operon in equal I strains and you isolate M R N A from two bacterial strains. One with a wild type lack operon genotype I plus P plus O plus Z plus Y plus and another with a lack minus genotype I plus P minus O superscript superscript C Z minus Y minus. The probe used in the northern blot analysis hybridizes to a portion of the lax C sequence. What will be the result from the lax Z probes hybridization for the mutant strain? Choice A no hybridization of the lax probe will occur. Choice B. There will be a rapid hybridization of the lax C probe. Choice C. There will be delayed hybridization of the lax C probe or choice D. None of the options is correct. So let's think through what our strains are going to express. Remembering that we do have that option of none of our choices being correct. So we want to know what will happen with a lack Z probe and a mutant strain that is lack minus and by indicating that it's lack of minus. It means that it doesn't produce the enzymes, allowing it to metabolize lactose. We see we have a bunch of different mutations here but telling us that it's lac minus means that it just, it doesn't produce the genes it needs. In this case, we look and see we have a P minus. So the mutation in the promoter region so that in itself would just shut down any transcription. So in this case, we have a lack Z probe, lac Z is one of the genes under the control of the LAC operon. So if our mutant strain is lack minus, that means no lack Z M R N A will be transcribed. And so if our probe is lax Z, that means there will be no hybridization resulting on this northern blot. So we look on here and that would be choice A no hybridization of the LA Z probe will occur. We know that choice d none of the options is correct. Can't be right since we have an answer here and choices B and C both involve hybridization taking place. So they're not our correct answer. So again, our answer here, uh the result from the lack of probes hybridization is choice. A no hybridization. See you in the next video.

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