140 



CELL HEREDITY 



TABLE 5.6 



The Genotypes of Offspring from a Cross of 



met* bio* thr leu \ met bio f/ir^ leu^ E. co/i with 



Different Couplings of the Loci for lac and 71 



(From Lederlk-rg ft al., 1951, C. S. II. Symp. (^htant. Bud.. 16:413) 

 Parents 



met bio 



2() 



lac 



33 



n 



thr leu 



A 



B 



(' 



The letter.s indicate the regions of the linkage group in which an exchange must 

 occur for a recombinant of the type indicated to be produced. Another exchange 

 must occur, of course, outside of this region to incorporate the genes in the frag- 

 ment from the IJfr into the recombinant DXA. The distances on the linkage 

 group are the averages of the frequency of exchange occurring in the different 

 regions. 



Example of the Exchanges that Occur in the 

 First Cross Above to Give the Results Tabulated 



.4 B C 



met^ bio^ lac- Tl-s thr" leu' 



viet^ bio'^ lac Tl-r thr'^ leu^ 



met bio lac'^ Tl-r thr'*' leii^ 



ABC 



mef^ bio'^ lac Tl-s thr^ leu'^ 



