348 CHAPTER 37 



REFERENCES 



Avery, O. T., MacLeod, C. M., and McCarty, M., "Studies on the Chemical Nature of the 

 Substance Inducing Transformation of Pneumococcal Types," J. Exp. Med., 79:137- 

 158, 1944; reprinted in Papers on Bacterial Genetics, Adelberg, E. A. (Ed.), Boston, 

 Little, Brown, 1960, pp. 147-168, and in Classic Papers in Genetics, Peters, J. A. 

 (Ed.), Englewood Cliffs, N.J., Prentice-Hall, 1959, pp. 173-192. 



Doty, P., Marmur, J., Eigner, J., and Schildkraut, C, "Strand Separation and Specific 

 Recombination in Deoxyribonucleic Acids: Physical Chemical Studies," Proc. Nat. 

 Acad. Sci., U.S., 46:461-476, 1960. 



Ephrussi-Taylor, H., "Genetic Aspects of Transformations of Pneumococci," Cold Spr. 

 Harb. Sympos. Quant. Biol., 16:445-456, 1951. 



Herriot, R. M., "Formation of Heterozygotes by Annealing a Mixture of Transforming 

 DNAs," Proc. Nat. Acad. Sci., U.S., 47:146-153, 1961. 



Hotchkiss, R. D., "Transfer of Penicillin Resistance in Pneumococci by the Desoxyribonu- 

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Lerman, L. S., and Tolmach, L. J., "Genetic Transformation. L Cellular Incorporation 

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QUESTIONS FOR DISCUSSION 



37.1. On what basis is transformation classified as a mechanism for genetic recombination 

 rather than as a mutation? Do you agree with this interpretation? Why? 



37.2. In view of the fact that native and renatured DNA are lighter in density than de- 

 natured DNA, was the experiment with denatured DNA, described on p. 315, 

 performed correctly? Explain. 



37.3. Devise an experiment to detect whether chain separation occurs during extensive /// 

 vitro synthesis of DNA. 



37.4. Do the transformation results obtained with chemically-hybrid DNA prove that 

 only a single DNA strand is required for cistronic action? Explain. 



37.5. Do the studies on transformation offer any clues as to the ploidy of Pneunwcoccusl 

 Explain. 



37.6. What kinds of problems would you study, if you had a feasible method of studying 

 the fate of individual cells exposed to transforming DNA? 



37.7. What do studies of genetic transformation reveal regarding the genetic nature of 

 conserved and nonconserved chromosomal DNA? 



37.8. Redraw Figure 37-1, showing hypothetical base sequences in double-stranded DNA. 

 Has your drawing any bearing on your answer to question 37.6? Explain. 



37.9. How can you explain the fact mentioned on p. 343 that the frequency of double trans- 

 formations is sometimes somewhat less than the product of the frequencies of the 

 single transformations? 



