DNA Double Helix

This 3D model shows DNA as two antiparallel sugar-phosphate strands wound into a right-handed helix, with adenine-thymine and guanine-cytosine pairs drawn as colored rods. The Unzip fork slider opens the helix from the top, and Auto replicate adds lighter new bases to each template strand. Students can hide hydrogen bonds, change rotation speed, and jump between Whole helix, Fork and Top down views. Use it to teach base pairing rules, the major and minor grooves, and why replication copies information accurately.

• Drag the Unzip fork slider from 0 to 1 and watch the Unzipped readout rise as the two strands separate.
• Switch on Auto replicate and watch lighter new bases fill in on each old strand.
• Toggle Hydrogen bonds off, then on, and count how many bonds join each base pair.
• Pick the Fork view and check that every new base matches its partner: A with T, G with C.
• Use the Top down view to see the helix from above and find the unequal major and minor grooves.

1. 1Describe the double helix as two antiparallel strands joined by base pairs.
2. 2Apply the base pairing rules A with T and G with C to a template strand.
3. 3Explain how each old strand acts as a template during replication.
4. 4Identify the roles of hydrogen bonds and the sugar-phosphate backbone.

Questions teachers ask