Suggested Answers for Insight Questions, Foundations in Microbiology, 7th Edition, listed by chapter, number, and page location.
A note to the users of these answers: These answers discuss some of the possible ways to approach the questions. They are not meant to be exhaustive in depth, but can offer information, suggestions, and points of view that will be helpful in understanding some of the concepts covered in the Insight and the chapter. Furthermore, they are not the final word--you may have thought of some other explanations that are just as valid. It is hoped they will serve to stimulate class discussion and inspire further research.

9.1, pg. 255 – The Packaging of DNA: Winding, Twisting, and Coiling
The long DNA molecules must be compacted to fit into the cell, and any genes on DNA that are not active will be in the coiled, unused form. In those areas of the DNA molecule that are being activated, an opposite system is at work--one which removes the coils, twists, and helices, so that the DNA strand is completely accessible. Bacterial cells have an enzyme system involving gyrases (a type of topoisomerase) that help to relax the supercoils so that the DNA helix becomes unwound. This then allows for a second type of enzyme, a helicase, to separate the helices of DNA into two strands prior to replication. Some forms of drugs (quinolones) function by stopping the actions of gyrases, which has the effect of inhibiting DNA replication and cell division.
9.2, pg. 256 – Deciphering the Structure of DNA
Several aspects of DNA had already been worked out prior to Watson and Crick: It was known that the proportion of A to T and G to C in DNA was always 50:50, regardless of the origin of the DNA, suggesting that these bases must go together in some way. It was realized that, being the genetic material, it must provide a code for being copied and passed on to new cells, and it must somehow store "information" that is a blueprint for cell function. The model for DNA structure really had the requirement of being somewhat simple and universal because a more complex cumbersome model would be less likely to fit all requirements. They consequently tossed out a triple strand hypothesis, and settled on a double stranded helix, with the non-coding sugar and phosphate forming the outside supports of the helices, and the bases lying between these, in A-T and G-C pairs. This automatically opened up the mechanism for copying, with the DNA serving as its own template for replication. Later other geneticists discovered that there was a link between the base codes and the nature of amino acids in a protein.
9.3, pg. 267 – Revising Some Rules of Genetics
Geneticists are continually discovering phenomena in their subject that appear to break established "rules". DNA may well have other minor functions besides encoding proteins and RNA. We know for sure that DNA is not restricted only to its function in _expression of genetic traits. For example, there may be regulatory areas that are not transcribed or translated but may be required for DNA replication. Telomeres and centromeres--specialized regions of DNA on eucaryotic chromosomes--are required for the separation, movement, and division of chromosomes during cell division. The introns and other seemingly non-processed genetic material appear to serve a variety of functions in managing RNA and ribosomes. Having large sections of non-coding DNA may also be a protection against damaging mutations of essential genes. It may well turn out that there is not really any "junk" DNA and that all of it serves some function in the genetic process.
9.4, pg. 272 – Replication Strategies in Animal Viruses
Human viruses have numerous variations in their precise genetics. In general, the genetic material of DNA viruses must enter the nucleus to be replicated and the genome of RNA viruses is replicated in the cytoplasm. Exceptions are 1) poxviruses, which contain DNA but are completely replicated in the cytoplasm, 2) influenzaviruses, RNA viruses that must enter the nucleus for completion of replication, and 3) retroviruses, which convert from RNA to DNA and then enter the nucleus for further replication. The main reason for this separation is that replication of DNA viruses usually requires the host DNA polymerase that exists primarily inside the nucleus. Examples are herpesviruses, adenoviruses, parvoviruses, and hepadnaviruses. RNA viruses such as poliovirus, rabiesvirus, and mumpsvirus do not enter the nucleus and complete the entire cycle in the cytoplasm using their RNA polymerases. RNA viruses do vary in the nature of their strands, whether ready to translate (+) or not (-), but this usually effects translation and transcription rather than replication.