408 CHAPTER 44 



44.2. How permanent need a change in a nucleotide be in order to qualify as being mutant? 



44.3. Would you consider the substitution of P^'- for P in the phosphate of a nucleotide 

 as a mutation? Why? 



44.4. What do you now think of the statement on page 199 that the only way we have of 

 detecting changes in individual recons is by the phenotypic changes these produce? 



44.5. What is meant by limit dilution? Is this technique used in studying TMV? Why? 



44.6. What conclusions can you draw from the observation that the number of nucleotides 

 is approximately constant in small RNA protein viruses? 



44.7. What conclusions can you reach from the fact that within about a day after infection 

 with a single particle of TMV, the cell can produce about 50,000 viral nucleic acid 

 molecules and about 100 X 10'' protein subunits? 



44.8. How could you prove, using infections by naked RNA of TMV, that this RNA 

 contains information for manufacturing TMV protein? 



44.9. Compare transformation with infection by naked virus nucleic acid. 



44.10. Discuss the view presented by F. Jacob that cancerous growths may originate because 

 virus infection causes the activation of DNA replication. 



