Discussion Questions — Part C 263 



12. Describe the essentially static experiments for measuring the interfacial 

 tension of large biological cells, such as amoeba and marine eggs, using 

 techniques of ultracentrifugation, shape distortion in a gravitational field, 

 and stress-strain relationships. 



13. Many investigators have been interested in the formation of DNA in 

 the reproduction of new bacteriophage particles. Review the present 

 evidence concerning the molecular mechanisms involved. 



14. Tobacco mosaic virus (TMV) consists of RNA and protein. It is 

 generally accepted that the RNA is essential for infection, but that the protein 

 is not infectious. Most investigators believe that the protein protects the 

 RNA, stabilizes it, and in some fashion helps it to enter the cell. Present an 

 outline of the evidence for this role of protein and RNA in TMV. 



15. Discuss the techniques of tissue culture. How have these been used to 

 study the effects of ionizing radiations on single human cells ? On the basis 

 of these studies, compare the sensitivities of human cells and bacteria to 

 ionizing radiations. 



16. What are the distinguishing features of Poliomyelitis, Coxsackie, and 

 ECHO viruses ? Describe the occurrence, classification, chemical properties, 

 physical dimensions, and infectivity of these enteric viruses. Indicate the 

 significance of tissue culture techniques in studies of these viruses. 



