DNA must make copies of itself to ensure genetic information is available for passing to daughter cells, and from generation to generation.
Replication is the making of a copy of DNA. Two ways are possible :
: conservative replication hypothesis (Click on the image to expand) : one daughter molecule contains both parent polynucleotides, and the other daughter molecule contains both newly synthesised strands.
A third hypothesis : dispersive replication in which each strand of each daughter molecule is composed partially of the original polynucleotide and partially of newly synthesised polynucleotide.
Two experiments were needed to establish the right mechanism :
Crick and Watson model of the double helix for DNA suggests a method by which replication may occur. The hydrogen bonds between the strands are broken and the molecule unwinds. Each strand can therefore act as a template to copy the DNA. Complementary nucleotides would then assemble, and the sugar phosphate backbone form by a condensation reaction.