Bio Lab Operons 10
.pdf
School
Santa Monica College**We aren't endorsed by this school
Course
BIOL 21
Subject
Biology
Date
Dec 21, 2024
Pages
3
Uploaded by SargentDiscoveryWallaby16
Lab 10 – Operons and Gene Expression RDVToday’s lab will be both group and individual work.Activity 1: Operons (group work, 5 points)Six strains ofE. coli(mutants a-f) that had one of the following mutations affecting thelacoperon wereisolated.a.nonsense mutation inlacYb.OCmutation at operator (cannot bind repressor) c.nonsense mutation inlacZd.inversion of the entirelacoperon e.super-repressor mutation (IS)f.inversion oflacZandlacY, but not promoterPor operatorOsequencesA) Which of these mutations will synthesize functional ß-galactosidase (the product oflacZgene) in the presence of lactose?OCmutation at operator, nonsense mutation inlacY, and nonsense mutation inlacZ.B) Partial diploid strains ofE. coliwere generated by inserting the entirelacoperon (inclucingIgene) of each of the above strains onto an F’ plasmid and crossing with individual F- strains. Pairwise analysis of each partial diploid strain were grown on minimal medium with lactose asthe sole carbon source. (Synthesis of ß-galactosidase and Permease are required for growth onthis medium.) Results are shown here (+ indicates growth; - indicates no growth). Whichmutant bacterial strain (1-6) contained each of the alterations (a-f) listed above? Place youranswers in the chart provided on the next page. (2 is mutant c)Hint: start with the one where all strains grow (which mutation would cause this?) Then,move on to one where almost none of the strains grow. Then, fill in the rest.F’ strain12 = c3456F- strain1-+-+-+2 = c+--+-+3---+-+
4++++-+5-----+6++++++Answers here:a =4b =5c =2d =3e =1f =6Activity 2: Gene Expression RDV (individual work, 5 points)Watch the 4 research deconstruction videos found on the Lab 10 page (~41 minutes).Then, go back to the Correa paper and answer the following questions/complete the followingtasks. Use Figure 1 to answer your questions. Note: the last 2 questions do not have a “correct”answer. Instead, they are designed to make you think creatively. Each answer should not havemore than 3 sentences.1.What question was addressed by the authors by using aCredriver in their mouse lineage?The question addressed by the authors was whether or not thermogenesis is regulated bydifferent ER alpha neurons in the VMHvl. Specifically, if there is the neurons of the VMHvl areheterogeneous.2.What conclusions did the authors make based upon their Cre allele driven expression?Since more magenta regions were found covering the ER alpha neurons in the VMHvl offemale mice, and less in males through tdtomato labeling, the authors found that the higher levelsof immunoreactivity were found in the females mice.
3.Do you agree with the authors conclusions? Why or why not? (In other words, do youthink the data could be interpreted differently?)Yes, I agree, because it was expected to find less ER alpha signaling in males, since it isalready known that estrogen seems to affect the energy expenditure of females, specifically.4.What controls (experimental, negative, or positive) do you think you would need for thistype of experiment?The positive control would be the living organisms tested, in this case, both the femaleand male mice. The negative control would be either just testing male mice to undergosingle-cell RNA sequencing to find the neuronal populations in the VMHvl, since it is alreadyknown there is less ER alpha signaling within their hippocampus.