390 CHAPTER 30 



McClintock, B., "Controlling Elements and the dene.'' Cold Spring Harb. Sympos 

 Quant. Biol., 21 : 197-216, 1 956. 



Moorhead, P, S., and Saksela, E., "Non-Random Chromosomal Aberrations in SV, () - 

 rransformed Human ( ells," J. ( ell < omp. Physiol., 62:57-83, 1963. 



Nichols, W. \V.. 1 evan, A.. Hall, B., and Ostergren, G., "Measles-Associated Chromo- 

 some Breakage. Preliminary Communication," Hereditas, 48:367—370, 1962. 



Peterson, P. A.. "The Pale Green Mutable System in Maize," Genetics, 45:115-133, 

 I960. 



Sandler, 1 ., and Hiraizumi, Y., "Meiotic Drive in Natural Populations of Drosophila 

 Melanogaster. \ 111. A Heritable Aging Effect on the Phenomenon of Segrega- 

 tion-Distortion," Canad. J. Genet. Cytol., 3:34-46, 1961. 



Li\lor, A. 1... "Bacteriophage-Induced Mutation in Escherichia coli," Proc. Nat. Acad. 

 Sci., U.S., 50:1043-1051, 1963. 



QUESTIONS FOR DISCUSSION 



30.1. How is the precision of the mitotic and meiotic processes related to the muta- 

 bility of the genetic material? 



30.2. Defend the statement that meiosis and mitosis are not intrinsic properties of 



genes. 



30.3. If whole genome changes represent a class of mutation, should the changes in 

 ploidy which occur in gametogenesis and fertilization be considered mutations? 

 Why? 



30.4. Does the activity of Dissociation provide evidence for the genetic control of 

 mutability? Explain. 



30.5. What evidence can you present that variegation is not always due to the effect 

 of a single pair of genes, one with unstable alleles? 



30.6. What characteristics of Dissociation resemble those of the episome F? 



30.7. Discuss the mechanisms by which segregation distortion is suppressed in nat- 

 ural populations of Drosophila. 



30.8. Discuss the hypothesis that the SD phenomenon involves an episome-like agent. 



30.9. In what respects is SD similar to and different from Ds? 



30.10. Do you suppose that all viruses cause a significant increase in the frequency of 

 chromosomal breakage? Explain. 



