The DNA ( Deoxyribonucleic acid ) contains the genetic instruction of the living beings. Everything that lives, every cellular life contains DNA, even some of the viruses. In eukaryotes, the DNA is stored inside the cell nucleus and in prokaryotes it’s stored insite the cytoplasm.
A cell duplicates when one or more of it’s DNA molecules duplicates and this is called DNA replication or DNA Synthesis. Read about the steps of DNA replication on dnareplication.info, there are six steps.

The DNA strands are consisted of nucleotides ( monomers that are made of a phosphate ). The strands that compose the DNA double Helix are antiparallel and are connected due to the hydrogen bonds between the nucleotide bases.

Read more about DNA, DNA replication and DNA double Helix on dnareplication.info !