These sugars, in turn, are interconnected by phosphate groups. These weak bonds allow the two strands to safely break apart, kind of like a zipper. This is how DNA separates and forms two duplicate molecules. First, the two strands of the double helix are separated by enzymes. Adenine bonds to thymine, and guanine bonds to cytosine.
Enzymes bind the bases to the new strand as it forms.
This process creates two double strands of DNA that are identical to the original double-stranded molecule. Here's how cells divide and multiply, forming two daughter cells from a single parent cell. The identical daughter cells are also identical to the parent cell. Images courtesy of Genentech Corp. Check out their graphics gallery for more cool pics.