IPTG Absent IPTG Present B-Galactosidase Permease B- Permease Galactoßsidase + O+ z+ Y+ + IS ot z+ Y+ + + + -ot z+ Y+ + + + oc z+ Y+ + + + + S OC z+ Y- + + + + OC z+ Y-/ F' + - ot z- Y+

Complete the table below by choosing a term(s) in Column B that associates with the term in Column A. Column A Column B Associated terms Repressor Activator Repressor & Operator RNA polymerase Corepressor RNA polymerase & Operon Promoter Operon & CRP LacZ CRP & Inducer Allolactose Inducer & Tryptophan Operator Tryptophan & B-galactosidase CAMP B-galactosidase & CRP binding site

The locations of the TATA box in two species of yeast, Saccharomyces pombe and Saccharomyces cerevisiae, differ dramatically. The TATA box of S. pombe is about 30 nucleotides upstream of the transcription start site, similar to the location in most other eukaryotic cells. However, the TATA box of S. cerevisiae is 40 to 120 nucleotides upstream of the start site. To better understand what sets the start site in these organisms, researchers at Stanford University conducted a series of experiments to determine which components of the transcription apparatus of these two species could be interchanged (Y. Li et al. 1994. Science 263:805–807). In these experiments, different general transcription factors and RNA polymerases were switched in S. pombe and S. cerevisiae, and the effects of each switch on the level of RNA synthesis and on the starting point of transcription were observed. The results from one set of experiments are shown in the table below. Components cTFIIB, cTFIIE, cTFIIF,…

Consider the trp operon found in E. coli. You have discovered a mutant strain of E.coli that contains a mutation in its trpR gene. This mutation prevents the trpR protein from binding to its small effector molecule. What would happen if both the wild type and mutant bacteria were put in an environment that contained lots of tryptophan? The normal (wild type) bacteria would have (i)________expression of the trp operon while the mutant bacteria would have (ii) _________ expression of the trp operon. A) (i) high (ii) high B) (i) low (ii) low C) (i) high (ii) low D) (i) low (ii) high

In bacteria, genes that are often used together are controlled by a single promoter. Explain why this is the case.

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…

In the bacteriophage T7 system used to express recombinant proteins, the gene of interest is fused to T7 promoter and T7 RNA polymerase is separately cloned into the same cell. What is the main reason this system uses T7 RNA polymerase instead of relying on the bacterial RNA polymerase? To restrict the expression of bacterial protein expression To enhance the amount of recombinant protein expression To enhance the expression of bacterial protein expression To restrict the amount of recombinant protein expression To enable the expression of T7 viral protein expression

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.

If a wild-type (normal, NOTmutated) E. coli strain is grown in a medium: a. without lactose or glucose, how many proteins (and which ones) are bound to the lac operon? b. Without lactose, but with glucose, how many proteins (and which ones) are bound to the lac operon??

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.