PROTEINS 125 



voted to those types of viruses infecting bacteria in the expectation that 

 information gained for these forms, called bacteriophages, might be ap- 

 plied to the viruses of plants and animals. 



Viruses are not typical cells. No respiration can be demonstrated 

 for them, and none of the enzymes of carbohydrate, lipide, and amino 

 acid metabolism have been found. Furthermore, they do not re- 

 produce independently, but increase in numbers only inside the host 

 cells. Apparently infection by a virus particle somehow induces the 

 host cell to cease some of its normal functions and synthesize com- 

 ponents for ne^v virus. Some portion of the original virus particle 

 then controls the assembly of the components, thus resulting in virus 

 production. Death of the infected cell frees the new particles and 

 permits spread of the infection. 



Obviously much has been learned about nucleic acids, yet work in 

 the field is unusually difficult and far more remains unknown than 

 has been clarified. One of the great lacks is that of sensitive tests for 

 nucleic acids of different kinds. 



REFERENCES 



Introduction to Protein Chemistry. S. W. Fox and J. F. Foster. John Wiley &: 

 Sons, New York, 1957. 



The Proteins. Edited by H. Neurath and K. Bailey. Academic Press, New York. 

 1953-1954. 



Advances in Protein Chemistry. Edited by M. L. Anson, J. T. Edsall, et al. Aca- 

 demic Press, New York, annual volumes beginning in 1944. 



Chemistry and Biology of Proteins. F. Haurowitz. Academic Press, New York, 

 1950. 



