382 CHAPTER 29 



QUESTIONS FOR DISCUSSION 



29.1. What is revealed aboul nucleocytoplasmic interrelationships from the study of 

 F? Of temperate phages? 



2 l >.2. What evidence can you present thai ((). -sensitivity is due to a virus rather than 

 a normal chromosomal gene? 



2 1 >..V In proving the existence o\ extranuclear genes, which operations (recomhina- 

 tional. mutational, functional, chemical) were utilized? Did our decision in- 

 clude their capacity for self-replication? Why? 



29.4. Discuss the genetic control of chlorophyll production in corn. 



29. s. Do you think that the study of nucleocytoplasmic interrelations in Paramecium 

 has any bearing upon differentiation processes in multicellular organisms? 

 Explain. 



29.6. As an experimental organism for genetic investigation, what are the unique ad- 

 vantages of Paramecium? 



29.7. Certain paramecia are thin because of a completely recessive nuclear gene, th. 

 What is the phenotypic expectation for the clones derived from exconjugants 

 of a single mating of ++ by +th? How would cytoplasmic mixing affect your 

 expectation? Why? 



29.8. According to the definition of a chromosome given on page 8, would you consider 

 kappa to be or to contain a chromosome? Explain. 



29.9. Keeping in mind the difficulties of proving the existence of extranuclear genes, 

 which do you think represents the primary genetic material in cellular organ- 

 isms, nuclear or extranuclear genetic material? Explain. 



29.10. Discuss the statement (p. 253) that DNA "seems to be absent in the cytoplasm." 



29.1 1. Do you think the evidence presented that sex in Chlamydomonas is based pri- 

 marily upon a single pair of genes is conclusive? Justify your answer. 



29.12. Report any evidence obtained since this account was written (November, 1964) 

 that the DNA in chloroplasts or in mitochondria has a phenotypic effect. 



