How does DNA replication occur?

DNA normally exists in the cell as a double-stranded structure, comprising of two complementary strands that are held together by hydrogen bonds.

DNA replication involves two main steps. Firstly, the enzyme HELICASE breaks the hydrogen bonds holding the two strands together, causing the strands to separate. Next, one DNA POLYMERASE enzyme binds to each strand of DNA and, using the strand as a template, generates a complementary strand.

Once this process is complete, there are now two double-stranded DNA molecules. This is known as SEMI-CONSERVATIVE replication, as each new DNA molecule is made up of one old strand and one new strand.