This animation shows how one molecule of double-stranded DNA is copied into two molecules of double-stranded DNA. 

DNA replication involves an enzyme called helicase that unwinds the double-stranded DNA. Other enzymes then copy each of the two strands. One strand is copied continuously. The other strand is copied in sections. The end result is two double-stranded DNA molecules.

This animation brings the process to life, showing three-dimensional representations of the molecules involved. Depending on students’ backgrounds, it may be helpful to pause the animation at various points to identify the molecules and describe their interactions.