Mechanism of DNA Replication 
form a twin polymerase. Since the chromosome 
has two strands of DNA, both of which must be 
repHcated, the twin polymerase likely serves the 
function of coordinately replicating both DNA 
strands at the same time. 
These studies on four (7, b, jS, r) of the eight 
accessory proteins of the holoenzyme have been 
greatly aided by having the genes (the informa- 
tional area in the DNA) for three of them (7, ^, r) . 
This has provided large quantities of proteins for 
studies via molecular cloning and overproduc- 
tion techniques. 
Our future plans include assignment of func- 
tion to the other four accessory proteins, and 
identification of the genes for the remaining five 
accessory proteins of the holoenzyme in order to 
obtain them in large quantity. Possession of the 
proteins in quantity would allow us to start inves- 
tigations on the structure of the holoenzyme. 
Identification of their genes would also allow 
construction of E. colt genetic mutants, which 
would provide further clues to the exact function 
of each subunit in replication. Clearly, many 
more studies by our laboratory and others are 
needed to gain a full understanding of the mecha- 
nism by which duplex DNA is replicated. 
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