CONCLUSIONS 



131 



be as many specific RNA molecules as there are genes. Finally, each 

 of these specific RNA molecules would act as a template for a 

 specific protein, according to the mechanism discussed in Chapter 2. 

 Such a scheme corresponds to the now familiar "slogan": DNA 

 makes RNA, and RNA makes protein. 



This catch-phrase, like all others, is an over-simplification, be- 

 cause it does not take into account the existence of nuclear and 

 cytoplasmic RNA's and the possibility of independent cytoplasmic 

 protein synthesis. The following scheme might perhaps help in the 

 understanding of the proposed relationship between DNA, RNA 

 and proteins in the different parts of the cell (see also Fig. 41). 



cy 



/-RNA ^\ ►RNA 



VcrcLeins// protein 



no 



Fig. 41. Scheme proposing relationship between DNA, RNA and proteins in 

 the different parts of the cell, chr: chromosomes; cy: cytoplasm; n: nucleus; 



no: nucleolus. 



2(?) 



DNA 



K?) 



■> Proteins of the chromosomes 



-> Nuclear RNA — >- Proteins of the nucleolus 



5 6 



— > Cytoplasmic RNA — > Cytoplasmic proteins 



References p. 133 J 135 



Cytoplasmic RNA -^ Cytoplasmic proteins 



