On its chromosome, an E. coli cell has a genotype of lacI− lacZ+ lacY+ lacA+. It has an F′ factor with a genotype of lacI+ lacZ+ lacY+ lacA+. What is the expected level of expression of the lac operon genes (lacZ+ lacY+ lacA+) in the absence of lactose?a. Both lac operons will be expressed.b. Neither lac operon will be expressed.c. Only the chromosomal lac operon will be expressed.d. Only the lac operon on the F′ factor will be expressed.

Predict the growth/color pattern you'd expect for a mutant that can't activate both sugar operons (like the lac and mal operon). Table 1: Options are blue, white, or either for NA plates; Table 2: Options are: growth or none for minimal plates). Table 1 ΝΑ Xgal + lactose Xgal + IPTG [S Minimal lactose maltose [ Select] Table 2 [Select] Xgal glucose [Select] [Select] [Select] [Select]

Predict the growth/color pattern you'd expect for a mutant that can't activate both sugar operons (like the lac and mal operon). Table 1: Options are blue, white, or either for NA plates; Table 2: Options are: growth or none for minimal plates). Table 1 either Table 2 no growth Xgal glucose white Xgal + lactose growth Minimal lactose ΝΑ blue Xgal + IPTG growth maltose blu

A sample of E.coli cells is transformed with a plasmid containing a transcriptional fusion including the promoter of an E.coli housekeeping gene and the LacZ gene. The transformed cells are plated out on selective medium containing X-gal. Which of the following best describes the likely results. a. Colonies will only be blue if lactose is also included in the growth medium. b. Colonies will only be blue if lactose and glucose are included in the growth medium c. Most of the colonies should turn blue. d. Presence of any white colonies may indicate deletion or mutation of the promoter. e. Both c. and d. are correct

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   a.Which operons would be functional under these conditions? b.What repressors would be made? (NOTE: name the repressors using their gene names) c.Which repressor(s) would be made in the inactive form? d.Which repressor(s) would be made in the active form? e.Which repressor(s) under these conditions can bind the operator sequence? f.Which repressor(s)under these conditions cannot bind the operator sequence?

1) A. What is the difference between a repressible vs, an inducible operon?   B. Using diagrams and words, describe how the Lac Operon is regulated by different levels of lactose and glucose. Be sure to show what’s happening at the molecular level, including the roles of lactose, glucose the repressor protein, cAMP and CAP.

Suppose that  a  new  mutation  lacIes, ('es'  stands  for  ‘extra-strength’)  has been discovered in the  lac operon  that allows  the  lac-repressor  to bind even  to  the  lacOc  operator.  Other  properties of  lacIes repressor  remain  normal (that is the same  as  of  lacI+).  Given  this genotype    Is P+ Oc Z+ Y-  / Ies  P+  O+ Z+  Y+  ,  under  which conditions will the gene  lacZ  be  transcribed  to  produce  β-galactosidase and the gene  lacY  transcribed to  produce  permease?     A)  With  lactose,  β-galactosidase and permease are  produced, without  lactose they  are  not produced B)  With  lactose,  β-galactosidase is produced, without  lactose it is not;  permease is never produced C)  β-galactosidase is always produced  and  permease is never  produced D)  With  lactose,  β-galactosidase and permease are  produced, without  lactose they  are  also produced E)  β-galactosidase is always produced  and  permease is produced only  in the  presence of  lactose

There is a mutation in sequence of the lac operator that prevents the lac repressor from being able to recognize and bind to it. What would the status of transcription of the lac operon be under each of the following circumstances? Explain your answers.   a-Lactose present, glucose present b-Lactose present, glucose absent   c-Lactose absent, glucose present   d-Lactose absent, glucose absent