18. Some viruses attack cells by attaching to their outer covering, entering, and taking over their genetic “machinery." Viruses are able to invade cells after first
attaching to their

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?

The cluster of developing cells from conception until birth is called an

Which macromolecule catalyzes chemical reactions this be considered enzyme chemical reactions thus he considering enzymes