DNA Model: Double Helix

DNA Model Materials



white bead

deoxyribose sugar (S)

red beads

phosphate group (P)

orange beads

adenine (A)

green beads

guanine (G)

blue beads

cytosine (C)

yellow beads

thymine (T)

clear connectors

hydrogen bonds



1. Attach a phosphate group (red bead) to the #5 position of the sugar group (white bead).

2. Attach any of the nitrogen bases (orange, green, blue, or yellow beads) to the # 1 position of the same sugar.
3. Make all of your nucleotides.
4. Build the following DNA molecule AGGCTAG.
5. Attach the phosphate of one nucleotide to the sugar of another nucleotide.Buil the left chain and then build the right chain.
6. Lay the left chain next to the right chain; line up the nitrogen bases; check to make sure that the A-T and G-C molecules are correct.
7. Join the two nitrogen bases with a hydrogen bond. Remember that (A) always pairs with (T) and (C) always pairs with (G).

8. Your DNA molecule should look like this:


9. Grasp the completed molecule by the base pair at each end of the strand.
10. Gently twist the molecule into the form of a spiraling rope ladder.
11. You have just made the double helix of DNA just like Dr. Watson!

12. Now build the following DNA molecule:





These pages authored and maintained by Marcella Dawson. Revised 3/2002 . Copyright 1995 CRPC GirlTECH. All rights reserved. . Email your comments. These pages were developed through GirlTECH '96, a teacher training and student technology council program sponsored by the Center for Research on Parallel Computation (CRPC), a National Science Foundation Science and Technology Center.