Biopolym. Cell. 1985; 1(5):227-233.
Replicon organization of the genome of higher organisms: critical analysis of racts and hypothesis
1Liapunova N. A.
  1. Institute of Medical Genetics, Academy of Medical Sciences of the USSR
    Moscow, USSR


The size measurement of replication units (replicons) by the method of DNA-fibre auto-radiography is critically analyzed. It is shown that the conception of «clusters of small replicons (30–50 u.m.)» is untenable. The model for organization of eucaryotic chromosome replication is suggested. This model is based on the known temporal order of replication of the functional chromosome blocks (G→G+→C) and on the existence of large replicons (100–200 u.m and more) being approximately equal to DNA fragments in one average-size functional block (300 u,m). The model is also based on the assumption Wiat the replicon initiations are grouped at three discrete short time intervals disrupted by prolonged time intervals during which only DNA chain elongation and replicon termination occur. The model explains uneven DNA synthesis during the S-period and facilitates a search of mechanisms for genetic control of the replication time sequence of different genome parts.


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