316 CHAPTER 23 



23.3. From our discussion ol drug-resistant mutants, is it valid to conclude that no 

 drugs arc mutagenic.' Explain. 



23.4. Criticize an attempt to prove the occurrence oi genetic recombination by con- 

 jugation in which two bacterial strains, each singly auxotrophic lor different 

 nutrients, are mixed and subsequently tested for prototrophs. 



23.5. \\h\ is it futile tii search c\tologicall\ for bacteria in the process of conjugation? 



23.6. Differentiate between and give an example of a selective and an unselccted 

 marker: a singl) auxotrophic and a prototrophic bacterium. 



23.7. In this chapter, what is the evidence that the two auxotrophs which produced 

 prototrophic progeny did so by conjugation rather than by mutation, genetic 

 transformation, or viral infection? 



23.8. In what ways does genetic transformation differ from conjugation? 



23.9. Invent suitable genotypes for parents, a zygote, and its clonal progeny, and 

 prove the existence of the zygote from the genotypes of the members of the 

 clone it produces. 



23.10. Ignoring the centromere, draw all the different ways you can represent a chro- 

 mosome whose recombination map is linear. 



23.11. Do you suppose that the discovery of sexuality in bacteria has important im- 

 plications for the practice of medicine? Why? 



