Imagine that two protein kinases, pk1 and pk2, act sequentially in an intracellular signaling pathway. when either kinase is completely inactivated, the cells don’t respond to the signal. doubly mutant cells that contain inactivated pk2 and permanently active pk1 respond in the absence of a signal. in the normal signaling pathway, does pk1 activate pk2 or does pk2 activate pk1? what outcome would you have predicted for a doubly mutant cell line with an activating mutation in pk2 and an inactivating mutation in pk1?

Assume that a student is given two different models of bacteria, with one model consisting of big bacteria and the other consisting of small bacteria. how can the student demonstate the theory of endosymbiosis using the models

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?

Vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a.) antibody, antibiotic b.) antigen, antibody c.)antibiotic, antibody d.)antibody, antigen