A mutation in E. coli is found that fails to induce the lac operon even when IPTG is added (IPTG is an inducer of the lac operon that enters the cell by passive diffusion). Which of the following could explain this phenotype (you may choose one or more answers)? a. Mutation in the promoter of the lac operon.
b. Mutation in the operator of the lac operon.
c. Mutation in the repressor for the lac operon.
d. Mutation in the Z gene for beta galactosidase.
e. Mutation in the Y gene for Lac permease.
f. Mutation in the gene for adenylate cyclase.
g. Mutation in the gene for CAP (or CRP) protein h) Mutation in the gene for rho factor
i. None of the above

Keeping in mind the life cycle of bacteriophages, consider the following problem: during the reproductive cycle of a temperate bacteriophage, the viral dna inserts into the bacterial chromosome where the resultant prophage behaves much like a trojan horse. it can remain quiescent, or it can become lytic and initiate a burst of progeny viruses. several operons maintain the prophage state by interacting with a repressor that keeps the lytic cycle in check. insults (ultraviolet light, for example) to the bacterial cell lead to a partial breakdown of the repressor, which in turn causes the production of enzymes involved in the lytic cycle. as stated in this simple form, would you consider this system of regulation to be operating under positive or negative control?

Which enzyme is responsible for “unzipping" the dna by breaking the hydrogen bonds between the nucleotides?

Astudent sees several ants walking up a wall following the exact same trail that an ant took earlier. she wants to apply the scientific method to determine how the ants detected the trail. which of these steps would come first in her application of the scientific method? perform an experiment by cleaning the scent away from part of the trail. draw a conclusion that the ants follow a scent trail. make a prediction about what the ants will do after she cleans away part of the trail. hypothesize that the ants are following a scent trail that the first ant left.