7. DNA and Chromosome Structure

In this chapter, we focused on how DNA is organized at the chromosomal level. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions:How do we know that viral and bacterial chromosomes most often consist of circular DNA molecules devoid of protein?

Write a short essay that contrasts the major differences between the organization of DNA in viruses and bacteria versus eukaryotes.

Contrast the size of the single chromosome in bacteriophage and T2 with that of E. coli. How does this relate to the relative size and complexity of phages and bacteria?

Assume that a viral DNA molecule is a 50-µm-long circular strand with a uniform 20-Å diameter. If this molecule is contained in a viral head that is a 0.08-µm-diameter sphere, will the DNA molecule fit into the viral head, assuming complete flexibility of the molecule? Justify your answer mathematically.