Name _____________________________________________________
Date __________________
Activity: Visualizing DNA
Goals:
1. To construct a paper model of a segment of DNA.
2. To show how the component parts of the DNA molecule “fit”
together to make a ladder shape.
Background Information: The simplest form used to represent DNA – deoxyribonucleic
acid - is a ladder shape. The ladder model can help us visualize how the components of the DNA
molecule: the four different nitrogen bases and the sugar-phosphate sides pieces or backbones
join together to form the complex structure of the “molecule of life.”
The four nitrogen bases that make up the rungs of the DNA molecule are adenine, thymine,
cytosine, and guanine. The nitrogen bases are abbreviated A, T, C, and G. It takes two nitrogen
bases to make one DNA rung, and adenine always pairs with thymine and cytosine always pairs
with guanine. Molecules of a sugar, ribose, and a phosphate form the side pieces, which make up
the DNA “backbone.”
If you could somehow twist this ladder model you’d be able to see that the true form of DNA is a
twisted ladder or double helix.
Materials: Preprinted paper puzzle or cut-out shapes of the four nitrogen bases and sugarphosphate sides on colored card stock paper, scissors, tape
1. What I Know: Write a sentence or two about what you already know about DNA.
2. Each student should cut out the following paper pieces to create the DNA paper model.
DNA Component
Sugar/phosphate pieces
Adenine Base
Thymine Base
Cytosine Base
Guanine Base
Symbol
A
T
C
G
Color
yellow/gold
green
purple
blue
pink
Number of Pieces
12
6
6
6
6
3. Make a six “rung” DNA ladder by carefully attaching rungs and side pieces. Put the
nitrogen base rungs together first, then add the sugar-phosphate side pieces. Use tape to
attach all the pieces to one another.
4. Once you and your partner have completed your portion of the DNA model, attach your
pieces together. Then add the segments from the other group members.
5. We will continue to attach all the segments until we create one long section of the DNA
molecule.
6. Questions:
a. Write a description of the DNA molecule based on your paper model. Describe
how all the DNA components fit together with one another. Be as specific as
possible.
b. How does DNA replicate?
c. Why is it important for the DNA molecule to replicate?