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, propose answers to the following fundamental questions:
(a) How do we know that viral and bacterial chromosomes most often consist of circular DNA molecules devoid of
protein?
(b) What is the experimental basis for concluding that puffs in polytene chromosomes and loops in lampbrush chromosomes are areas of intense transcription of RNA?
(c) How did we learn that eukaryotic chromatin exists in the form of repeating nucleosomes, each consisting of about 200 base pairs and an octamer of histones?
(d) How do we know that satellite DNA consists of repetitive sequences and has been derived from regions of the centromere?