586 GENETICS AND EVOLUTION 



A 



Su.bsti'a-'bc 



Enzyme- substi'-ate, complex 



i 



This -molecule is 

 not a. Substra.tc.'" 

 It doc5 not fit on 



yjl TTEJ 



_r the e.nzyrae 



- Surf a.ce. 

 J 



A :» B 



Split prod-ucts 



B 



Qbtus 



G&n& 





Gene molecule -wibK 

 specific sui^fa-ce 



Ge-ne- inolccule produces 

 a. templa-te. 



/ 



Te.rapia.tc molecule produC£.S 

 e.n-z,ymz xnoleculcS -with specific surf a-ce 



Figure 33.5. Diagram comparing the theory of the production of an enzyme mole- 

 cule by a gene via a template with the theory of the formation of an enzyme-substrate 

 complex. 



specific conformation is transferred either directly or via an intermediate 

 template to the enzyme (Fig. 33.5). This theory requires that there be a 

 separate gene for each type of enzyme, and there is quite a bit of experi- 

 mental evidence which indicates that this is true. 



Our current idea of gene function may be summarized as follows: 

 The materials transferred from one generation to the next in the nucleus 

 of the egg and sperm, the genes, are templates composed of DNA and 

 protein. These templates are duplicated and are distributed during cell 

 division to all the daughter cells that make up the animal or plant 

 body. In each cell, the DNA, either by itself or in combination with 

 protein, produces an intermediate template made of ribonucleic acid 

 and protein. This intermediate template passes from the nucleus to the 



