102 



MICROSOMAL PARTICLES 



H-q Dry Weight /ml 

 200 



150 



100 



50 



p-FPhe 



Thiala 



120 240 



Time (min) 



360 



Fig. 1. Effects of p-fluorophenylalanine and (3-2-thienylalanine on the growth of yeast. 



Synthesis of Cell Material during Linear Growth. Washed cells from an 

 exponentially growing culture were placed in two flasks, one containing C 14 

 glucose, and the other containing C 14 glucose and /?-FPhe (10~ 2 M final 

 concentration). 



Optical density was followed throughout the experiment, and 10-ml samples 

 taken at intervals were placed in precooled centrifuge tubes (0° C). The 

 cells in the control culture were allowed to increase 2.6 times, and those in 

 the linear culture 1.9 times. The samples were fractionated (Halvorson [4]), 

 and the radioactivity of the hot-TCA-soluble fraction (containing the nucleic 

 acids) and of the protein fraction (hot-TCA-insoluble) was determined. The 

 differential rates of synthesis of total hot-TCA-soluble material and of total pro- 

 tein were then plotted. The differential rate of synthesis of a component X is 

 expressed by AX/AM, M being the increase in mass during the time necessary 



Fig. 2. Effect of /7-fluorophenylalanine on the size of yeast cells. Pictures taken initially 

 (.i), after an optical density increase of 2.7 times (B), and 5.4 times (C). 



