The term "unzipping" in the DNA replication refers to the breaking of the hydrogen bonds. <span>In the process of DNA replication, DNA helicases
disentangle DNA at positions known as origins where synthesis will be
initiated. DNA helicases continue to uncoil the DNA creating a structure called replication fork
as they unzipped apart. The process of breaking the hydrogen bonds between the
nucleotide base pairs in double-stranded DNA needs energy. Helicases require
energy stored in an ATP molecule to break the bonds. </span>
