Question

In: Biology

Which is likely to occur in E. coli cells that are grown in milk (Hint: Milk...

Which is likely to occur in E. coli cells that are grown in milk (Hint: Milk contains lactose sugar)?

The lac operon is shut off, and the cells will not produce lactose-utilizing enzymes.

The lac repressor is inactivated, and the cells will produce lactose-utilizing enzymes

The lac operon is turned on, but the bacteria will not produce lactose-utilizing enzymes. ---- wrong

Solutions

Expert Solution

Answer: The lac repressor is inactivated, and the cells will produce lactose-utilizing enzymes

Explanation: Lac operon is an inducible operon that is only activated when the medium contains lactose. Lac operon consists of a regulatory gene, operator, promotor, and three structural genes. The regulatory gene encodes for active repressor proteins. The repressor protein binds to the operator gene so that RNA polymerase could not bind to the promoter resulting in the turning off of the operon. Let's consider two cases:

The case I: When the lactose is present in the medium.

Lactose will bind to the repressor resulting in the inactivation of repressor molecules. So repressor molecules could not bind to the operator and RNA polymerase initiates transcription of structural genes. The structural genes encoding for the enzymes for the metabolism of lactose.

The case II: When lactose is absent in the medium:

When lactose is absent in the medium, the repressor protein binds to the operator gene so that RNA polymerase could not bind to the promoter resulting in the turning off of the operon.


Related Solutions

1. In E. coli cell is grown in the presence of high amounts of glucose. Which...
1. In E. coli cell is grown in the presence of high amounts of glucose. Which of the following is true? a. The cell will use lactose as a carbon source. b. The level of cyclic AMP in the cell will be low. c. The level of cyclic AMP in the cell will be high. d. Transcription of mRNA from the lac operon will be high e. The cell will die. 2. Enhancers are a. proteins located adjacent to promoters...
Consider a colony of E. coli cells in which the gene for the CRP protein is...
Consider a colony of E. coli cells in which the gene for the CRP protein is deleted. Describe the effect of that this deletion will have on the arabinose operon in terms of levels of Ara A protein (one of the proteins encoded by a gene in the ara operon) when the cells are grown in media containing arabinose but no glucose. Explain your reasoning.
In an experiment, E. Coli that are auxotrophic for methionine, tryptophan, and adenine biosynthesis are grown...
In an experiment, E. Coli that are auxotrophic for methionine, tryptophan, and adenine biosynthesis are grown on petri dishes containing rich media with all of these nutrients. The bacteria grow into normal colonies. The same bacteria are plated onto media that is lacking those 3 nutrients (minimal media) and no growth is observed. A second strain of E. Coli which is auxotrophic for histodine, and leucine is also able to grow on rich media but not minimal media. After mixing...
A partial diploid strain of E. coli, grown in the presence of lactose and allolactose, does...
A partial diploid strain of E. coli, grown in the presence of lactose and allolactose, does NOT produce any functional beta galactosidase. What is the possible genotype of the cells? (genotypes on the chromosome / genotypes on the plasmid) lacI+ lacP+ lacOC lacZ+ / lacIS lacP+ lacO+ lacZ+ lacI+ lacP+ lacOC lacZ+ / lacI- lacP+ lacO+ lacZ+ lacI+ lacP+ lacOC lacZ+ / lacI+ lacP- lacO+ lacZ+ lacI+ lacP+ lacO+ lacZ+ / lacIS lacP+ lacO+ lacZ+
PREPARATION OF COMPETENT CELLS and TRANSFORMATION: 2a. We will be preparing competent MM294 (E. coli) cells...
PREPARATION OF COMPETENT CELLS and TRANSFORMATION: 2a. We will be preparing competent MM294 (E. coli) cells using a chemical treatment of CaCl2. What are MM294 cells, why do we use them? Define “competent” cells and describe why/how CaCl2 makes cells “competent”. Why is “mid-log” phase important? Support your drawing with a cartoon of what cells “look like” before and after treatment. 2b. What does “heat-shock” do (in the transformation procedure)? 2c. What is LB? What does “LB” stand for and...
Thinking of lactose operon regulation, what happens when E. coli is grown in medium with glucose...
Thinking of lactose operon regulation, what happens when E. coli is grown in medium with glucose and lactose? Group of answer choices neither Cap/cAMP activator nor LacI repressor are bound to a regulatory DNA sequence. LacI repressor is bound to the OPERATOR sequence but Cap/cAMPactivator is not. Cap/cAMP activator is bound to the CAP motif but LacI repressor is not. both Cap/cAMP activator and LacI repressor are bound to the OPERATOR sequence.
Question 7 A strain of E. coli is grown under aerobic conditions. However, this strain has...
Question 7 A strain of E. coli is grown under aerobic conditions. However, this strain has an inactivating mutation in the enzyme that converts Pyruvate to Acetyl-CoA. What is the consequence of this mutation? 1. The organism cannot fully oxidize glucose, but can metabolize fats and some amino acids 2. The organism can metabolize as normal 3. The organism cannot carry out glycolysis Question 4 Which of the following organisms are directly beneficial to vascular plants? 1. mycorrhizae 2. water...
Which of the following statements is TRUE? E. coli sigma factors all recognize one E. coli...
Which of the following statements is TRUE? E. coli sigma factors all recognize one E. coli gene Prokaryotic mRNAs contain sequences for sigma factor binding mRNA in both E. coli and humans are translated with the same translation machinery E. coli sigma factors all bind to the core RNA polymerase mRNA always contains the nucleotide sequence encoding just one protein
Consider a colony of E. coli cells that have a mutation in the lac I gene,...
Consider a colony of E. coli cells that have a mutation in the lac I gene, resulting in a LacR protein that cannot bind to allolactose. Describe the effect that this mutation will have on the lac operon in terms of βgal protein levels when the cells are grown in media containing lactose but no glucose. Explain your reasoning.
1. In an experiment, you grow E. coli cells in the lab at different temperatures. After...
1. In an experiment, you grow E. coli cells in the lab at different temperatures. After the growth, you isolate their cell membranes, perform complete hydrolysis of their cell membranes and isolate and quantify the percentages of different fatty acids in your final sample. How would you expect the fraction of myristic acid to change as you increase the temperature?   2. Succinyl-CoA is a negative regulator of α-ketoglutarate-dehydrogenase complex. Explain why this makes sense, and propose a possible mechanism for...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT