Suppose that E. coli sustains a mutation in its gene for the lac operon depressor making the repressive ineffective. How would this mutation affect the bacterium's ability to catabolize lactose? Would the mute to strain have an advantage over the wild-type strain?

You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan.  Using your knowledge of operons and their regulation, answer the following questions using the dropdown menus provided in Canvas. Which operons would be functional under these conditions?   What repressors would be made? (NOTE: name the repressors using their gene names)   Which repressor(s) would be made in the inactive form?   Which repressor(s) would be made in the active form?   Which repressor(s) under these conditions can bind the operator sequence?   Which repressor(s)under these conditions cannot bind the operator sequence?   What effect does lactose have on the bacterial cell’s lac operon?    What does the absence of glucose do to the bacterial cell?    You now add tryptophan to the cell. What would happen to the bacterial cell and its trp operon?   What kind of regulation does lactose provide to an operon’s…

The lac operon has which of the following characteristics? O 1) usually requires an activator protein bound to the promoter to be transcribed. O 2) is inactive in the presence of lactose. O 3) is active in the presence of a repressor. O 4) Is a constitutively active operator. O5) is only active in the presence of lactose.

Tryptophan (Trp) attenuation is an extra mechanism of regulation of trp operon when trp level is too high. Attenuation causes premature transcription termination. b)    Predict what will happen if trp repressor lose its allosteric effect.

To study the lac operon, you engineer a strain of E coli to have a lac operon in which the lac Z gene is replaced by the gene for green fluorescent protein (GFP). Expression of GFP generates a green color in the cells that can be easily quantitated with a fluorescence microscope. You test the activity of the operon in the absence of the inducer IPTG, the presence of the inducer IPTG and the presence of an antibiotic the completely inhibits RNA polymerase (i.e. no gene expression). You then use this system to test the effects of various mutation on the activity of the operon. Match the following mutations with the activity (A, B or C) you would expect to observe with the mutation. All experiments are done in the presence of IPTG unless otherwise stated.

Many amino acid biosynthetic operon under attenuation control are also under negative control. Considering that the environment of a bacterium can be highly dynamic, what advantage could be conferred by having attenuation as a second layer of control?

A haploid E. coli cell has the genotype I ¯ P+ O+ Z+ Y ¯ where the I ¯ indicates that the repressor protein cannot bind to the operator due to a mutation. Which of the following statements about cells with this lac operon genotype are correct? I ¯ P+ O+ Z+ Y ¯ Select all that apply. β-galactosidase will be transcribed constitutively. The cells are able to import lactose across the cell membrane. The cells are lac+ and are able to grow on a medium with lactose but no glucose. RNA polymerase can bind to the promoter.

If a researcher moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following results would you expect? A) The three genes of the lac operon will be expressed normally. B) The repressor will not be able to bind to the operon. C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. D) LacZ will not be transcribed and Beta galactosidase will not be produced.

Which of the following is true about the Lac operon? Group of answer choices An operon with a constitutive operator (O^C mutation) will transcribe in the presence of a super repressor It is a positive repressible operon that is influenced mainly by fluctuations in glucose levels Produces a large quantity of tryptophan in order to synthesize lactase It is found in eukaryotes and is responsible for creating an enzyme that breaks down lactose

The tryptophan operon of E. coli represents an example of a gene regulatory system which is: a repressible system (normally turned on, but can be repressed) a repressible system (normally repressed, but can be turned on) an activator system (normally turned off, but can be activated) an activator system (normally activated, but can be turned off) all of the above