Chapter 7, Problem 30P

a.	Seymour Benzer’s fine structure analysis of the rII- region of bacteriophage T4 depended in large part on deletion analysis as shown in Fig. 7.25. But to perform such deletion analysis, Benzer had to know which rII bacteriophage strains were deletions and which were point mutations. How do you think he was able to distinguish rII- deletions from point mutations?
b.	Figure 7.25c shows Benzer’s fine structure map of point mutations in the rII region. A key feature of this map is the existence of hotspots, which Benzer interpreted as nucleotide pairs that were particularly susceptible to mutation. How could Benzer say that all of the independent mutations in a hotspot were due to mutations of the same nucleotide pair