VIRAL FUNCTIONS: ORDER AND DISORDER 



cellular organelle to which it is attached; that is, one duplication 

 occurs every 20 to 50 minutes. The prophage is obviously subject 

 to the system that controls the duplication of the bacterial chromo- 

 some. What is this system? As a matter of fact, the first question 

 is: Does such a system exist? 



p iv»«»* prophage 



F — sexual factor 



c bacteriol chromosome 



autonomous D N A of 

 homologous supennfectmg phage 



Figure 32. Integrated and Nonintegrated Genetic iMaterial. 



The Ivsogenic bacterium carries two prophages: one of them is attached to 

 the bacterial chromosome, the other to the fertihzing factor or sexual factor (F). 

 It is infected by a mutant of the homologous phage. Since the lysogenic bacteria 

 is immune, the vegetative phase is not initiated. The autonomous genetic 

 material of the superinfecting phage does not multiply, whereas both integrated 

 phage genetic materials do divide. 



In a normal cell, in a normal microorganism, the multiplication of 

 the chromosome is in harmony with the growth of the cell and its 

 division. When things proceed normally, no problem is posed. If 

 the replication of a cellular chromosome should be impaired, the 

 cell would die. A lethal defect of an indispensable cellular organelle 

 obviously cannot be perpetuated. But such a lethal defect can exist 



[81] 



