Elementary plant Biochemistry and Biotechnology (2+1)

Models for the replication of DNA

• The replication of cellular DNA was originally conceived as two models: conservative and dispersive. In conservative model, the parental DNA remains unchanged and gets passed to one daughter cell, whereas newly synthesized DNA gets passed to the other. But in dispersive replication, new DNA synthesis is interstitial (small openings), and each daughter cell receives a mixture of parental and newly synthesized DNA.


• In a third, semi conservative model, proposed by Watson and Crick, the parental strands remain unchanged, but the duplex is separated into two halves. Each parental strand acts as a template for replication and the daughter duplexes have one parental strand and one daughter strand each.


• The semi conservative model holds good for cellular DNA, but the single stranded genomes of viruses and some plasmids replicate conservatively - the structure of the single parental strand is conserved following replication.