DNA S Phase

3D Structure of DNA During S Phase

CPK Color Scheme C O N P

On this page, you can see DNA being replicated during S-phase of the cell cycle. The DNA polymerase is shown as in cartoon form with secondary structure colors. Three strands of DNA are visible (red, blue and yellow). You can click and drag to see the shape before clicking on the buttons below.

Hide the protein for now and show the two strands of the oringal DNA. The blue non-template strand is shorter which helps with visualization but would not be short in real life. The red template strand is long enough to serve as template for the DNA polymerase.

Bring back the yellow, growing strand of DNA that is the reverse complement of the red template strand. Note how the blue, non-template strand is way off to the side, away from the active site of the DNA polymerase. Afer a couple seconds, the most recently added nucleotide will appear in CPK colors, followed by the next nucleotide to be added.

Bring the protein back and see where the newest base that will be added to the 3' end of the growing yellow strand is sitting in the active site of the purple DNA polymerase protein enzyme.

Navigate around the DNA polymerase to see where the old DNA enters the enzyme and where the new DNA double helix will exit the enzyme.

Genomics

Biology Home Page