THE HEREDITARY ORDER: GENETIC INFORMATION 



template. Experimental data obtained so far are in full agreement 

 with the Watson-Crick hypothesis. 



Can we learn something more? Three mechanisms could be en- 

 visaged for the replication of the DNA. These are called conserva- 

 tive, semiconservative, and dispersive (Figure 10). 



Figure 10. 



(a) Conservative Mechanism. 



The duplex is reproduced as a whole. 



(b) Semiconservative Mechanism. 



Each chain serves as a template for the production of a complementary 

 one. 



(c) Dispersive Mechanism. 



Pieces of the parental chains are scattered among the offspring duplexes. 



a. In the conservative mechanism, the duplex is reproduced as a 

 whole: one of the daughter duplexes is the parent, the other one 

 entirely new. 



b. In the seviiconservative mechanism, each chain serves as tem- 

 plate for the production of another complementary one. In this 

 model, each of the daughter duplexes is composed of two parts: one 

 chain is parental, the other new. This is the original hypothesis put 

 forward by Crick and Watson in 1953. 



c. In the dispersive mechanism, the integrity of the chains is not 

 maintained. Pieces of the parental chains are scattered among the 

 daughter duplexes. 



[31] 



