VII. SYNTHESIS OF RNA AND RIBOSOMES 



335 



The effect of chloramphenicol is very much what one would expect 

 from this model. The predominant effect is the accumulation of what 

 appears to be eosome material by both sedimentation and column 

 analysis. Moreover, the base composition of this material is like that 

 of ribosomes. Apparently chloramphenicol inhibits the addition of pro- 

 tein to eosomcs. The minor peak appearing at about 24S may represent 



Biosynthesis of E. Coli ribosomes 



EOSOME 



43S 



"^ 



(Peak-l4S) 

 ( Range =8S-20S) 



RIBOSOME 



i 



|50S 



70S 



Isosi 



l/ 



Areas approximate molecular weights 

 I ~| = .55x 10^ M.W. units of RNA 

 i = . 17x10^ M.W.unitsof protein 



Fig. 27. The biosynthesis of ribosomes in E. coli. The open and shaded areas are 

 proportional to weights of RNA and protein, respectively. 



small quantities of neosome produced in the presence of chloramphenicol 

 since even at 200 /xg/ml the inhibition of protein synthesis is not abso- 

 lutely complete. 



One feature of the general sequence of ribosome synthesis deserves 

 further mention. The addition of RNA and protein occur in time sepa- 

 rated stages. This is clear from the very observation of RNA rich 

 intermediates. 



VIII. Composition of Newly Formed RNA 



A. AMBIGUITIES 



If an end product is stable, then newly formed material should show 

 the same com]iosition as does the total. If, however, two components of 



