A mutant E. coli strain, grown under conditions that normally induce the lac operon, does not produce ß-galactosidase. What is a possible genotype of the cells?

A. lacl+ lacP+ lacO+ lacZ+ lacY+ lacA+
B. lacI+ lacP+ lacOc lacZ+ lacY+ lacA+
C. lacI- lacP+ lacO- lacZ+ lacY+ lacA-
D. lacI+ lacP- lacO+ lacZ+ lacY+ lacA+
E. lacI+ lacP+ lacO+ lacZ+ lacY- lacA+


Ans: D. lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

Biology & Microbiology

You might also like to view...

One key principle of natural selection is that there is competition for resources

A. true B. false

Biology & Microbiology

Match each toxin type below with its effect on the human host.

a. exotoxins b. endotoxins 1. have systemic effects such as fever, inflammation, diarrhea, and shock 2. have effects on a specific cell type

Biology & Microbiology

Each chromosome has one or more ________ site(s) where replication begins.

A. bifurcate B. promoter C. origin D. replicon

Biology & Microbiology

Which of the following structures allow aquatic bacteria to orient themselves in the Earth's magnetic field?

A) Carboxysomes B) Gas vacuoles C) Magnetosomes D) Polyphosphate granules

Biology & Microbiology