Semi-conservative replication describes mechanism by which DNA is replicated in all known cells. This mechanism of replication was one of three models originally confirmed by Messelson and Stahl. Semi-conservative replication would produce two copies that each contained one of original strands and one new strand.

The double stranded helical structure of DNA, takes a turn after every 10 base pairs which is noted to be as 3.4 nm. This is called as a pitch (distance). 0.34 nm is considered to be distance between 2 base pairs.