Viruses: Recombination in Bacteriophage {II) 399 



Helinski, D. R., and Yanofsky, C, "Correspondence between Genetic Data and the Position 

 of Amino Acid Alteration in a Protein," Proc. Nat. Acad. Sci., U.S., 48:173-183, 1962. 



Jacob, F., and Monod, J., "Genetic Regulatory Mechanisms in the Synthesis of Proteins," 

 J. Mol. Biol., 3:318-356, 1961. 



Jacob, F., and Wollman, E. L., "Genetic Aspects of Lysogeny," pp. 468-500 in A Symposium 

 on t/ie C/iemical Basis of Heredity, McElroy, W. D., and Glass, B. (Eds.), Baltimore, 

 Johns Hopkins Press, 1957. 



Jacob, F., and Wollman, E. L., "Viruses and Genes," Scient. Amer., 204 (No. 6):92-107, 

 1961. 



Kaiser, A. D., and Jacob, F., "Recombination Between Related Temperate Bacteriophages 

 and the Genetic Control of Immunity and Prophage Localization," Virology, 4:509- 

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 Brown, 1960, pp. 353-365 



Rubenstein, L, Thomas, C. A., Jr., and Hershey, A. D., "The Molecular Weights of 2T 

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Watson, J. D., and Maalde, O., "Nucleic Acid Transfer from Parental to Progeny Bac- 

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See last portion of Supplement V. 



QUESTIONS FOR DISCUSSION 



43.1. In what respects is 0X similar to and different from an F particle? 



43.2. A temperate phage is known which is capable of transducing any known chromosomal 

 marker in E. coli. Would you expect to be able to locate the chromosomal site 

 for its prophage? Explain. 



43.3. Does the finding that a single phage particle may transduce a bacterial fragment 

 carrying not only a bacterial marker but two linked prophages have any bearing 

 upon the essentiality of the entire phage genome for infection and/or the production 

 of phage progeny? Explain. 



43.4. How can you distinguish a mutant in the rll region from one in the rl or rlll region? 



43.5. Describe how the trans test is used to show functional complementation between 

 two mutants in phage. 



43.6. What would you expect to be the near-maximum number of nucleotides transduceable 

 by a phage which is still capable of phage activity? On what is your opinion based? 



43.7. How would the estimated nucleotide length of a recon be affected if 80% of phage 

 DNA was actually conserved? If the average protein-specifying cistron was 2000 

 nucleotides long, how many different proteins could be specified by T4? by 0X174? 



43.8. What do you consider to be the most remarkable feature of 0X174? 



43.9. Mutants which show functional complementation in the pan-2 region of Neurospora 

 can be arranged in the same linear order by complementation and by genetic recombi- 

 nation. Is it necessarily true that both maps also will be identical for other regions? 

 Explain. 



43.10. What is a cistron? How is your answer related to its length in nucleotides? 



43.11. What have you learned in the present Chapter regarding the chemical nature of 

 different genetic units? 



