Name_______________________________
CB
21
Design your Own DNA Model Molecule
Supplies Needed (per model)
 2 white/tan 12” chenille stems (aka “pipecleaners”)
 2 colored 12” chenille stems
 4 sets of 6 each (pony) beads (A, T, G, C)
 22 ivory or white beads (sugar)
 22 black beads (phosphate)
 scissors
 ruler
Directions:
1. Cut the white chenille stem into 2 inch sections. You will need 12 pieces.
2. The pony beads represent the 4 different bases:
Adenine (A) - __________________ Thymine (T) - __________________
Guanine (G) - ___________________Cytosine (C) –____________________
4. Thread beads representing an Adenine and Thymine base pair onto one
of the 2-inch white chenille stems. (Remember that A always base pairs
with T) Prepare 6 of these segments.
5. Prepare 6 Guanine and Cytosine base pairs using the remaining beads.
6. Connect one white chenille segment to the colored chenille stem approx. 1
cm from the bottom. Wrap the end of the white stem around the colored
stem. Connect the other end to the second colored chenille stem (see
photo). This is where you can be creative with the genetic code - you can choose to
make your own DNA sequence!
7. On the first strand put an ivory bead and then a black bead. On the other strand put a
black bead and then an ivory bead. The two strands actually run in opposite
directions and this helps us see the order. After these beads you can put another set
of bases on their white pipe cleaner.
7. Follow the same procedure for the remaining white segments and beads. Add each
consecutive base pair (white chenille segment after the sugar and phosphate beads
making sure to keep the black and white pattern running opposite on each side.
8. When all 12 base pair segments have been added to the DNA molecule, you should
have a model that looks like a ladder.
9. To make your double helix, twist your model slightly so the molecule forms a spiral.
DNA molecules have a right-handed helix shape that winds in one direction. You can
figure out the direction by sliding the fingers of your right hand along backbone. If it
is right-handed, your thumb should be moving forward while you do this.
10. CONGRATULATIONS! You have created your own unique DNA molecule. The
sequence of the base pairs in the DNA ladder is what makes different DNA molecules
unique.
Name_______________________________
Questions!
1. Look at the backbone (outside edges) of the DNA molecule.
The black beads are ___________________. The white beads are ____________________
2. What colors represent the 4 nitrogenous bases?
A= ______________________
T = _______________________
G=______________________
C = _______________________
3. If you cut your molecule in half so that you only had one side of the ladder, could
you rebuild the other side? EXPLAIN why or why not!
1. Fill in your DNA code just showing the letters A, T, G, and C to represent the bases.
(P=phosphate, S=sugar)
SP – SP -
SP – SP -
SP – SP -
SP – SP - SP – SP - SP – SP -
PS – PS - PS – PS - PS – PS - PS – PS - PS – PS - PS – PS 4. Compare your DNA molecule to two others.
a. List two ways they are similar?
b. List two ways they are different?
5. Think for a second. How is it possible that these four bases (A,T, G, C) are
responsible for making all life as we know how? It’s okay if you don’t know but do
some brainstorming and come up with something!
Name_______________________________
6. What does DNA stand for? _______________________________________