DNA replication - Conservative, Semi-conservative and Dispersive methods

The ability to reproduce is the most fundamental properties of all systems. Organisms duplicate by sexual or asexual methods.

Cell replicates by cell division. During cell division, the genetic material should also be replicated. The process is called DNA replication.

DNA as a genetic material performs two important functions:

1. Autocatalytic function that is directs its own synthesis and

2. Heterocatatlytic function as its directs the synthesis of RNA and proteins.

During DNA replication; each chain of double helix can serve as a template for the synthesis of other. Each parental single strand is a template for the synthesis of new daughter strands.

Modes of replication: Three proposed models of DNA replication are conservative, semi conservative and Dispersive.

• Conservative: all the strands forms are newly synthesized

• Semi-conservative: here of the two newly formed strands one will be parental and other will be a newly synthesized strand. Each parental strand serves as a template for the synthesis of daughter stands

• Dispersive: Newly synthesized d strands will be a mixture of parental and newly synthesized strand pieces. Here replication involve fragmentation of a parent double helix and intermixing of pieces of the parent strands with newly synthesized strands

Semi conservative mode of DNA replication was proved beyond doubt to be the basic mode of replication by Meselson and Stahl’s experiment (1958) in E. coli.