DNA Model in a Box
Introduction
DNA is an extremely complex molecule composed of a series of nucleotides. Each nucleotide unit
consists of a sugar (deoxyribose), a phosphate, and one of four nitrogenous bases: adenine, guanine,
cytosine or thymine.
Materials
 Scissors
 String
 Shoebox
 Straws (5 different colors; can be colored with a marker)
 Pipe cleaners
 Metric ruler
 Plastic beads (1 color)
Procedure:
1. Cut a piece of string approximately three times the length of the shoe box.
2. Remove the lid from your box and place the box flat on your desk. Find the two narrow sides of
the box. With the scissors, poke two holes in each of the narrow sides about 6 cm apart. If done
correctly the two holes in one end should be in line with the two holes in the opposite end.
3. Put the string inside the box and pull an end through one hole on end A to the outside of the
box and through the other hole on end A into the box.
4. Hold the two ends of the string and pull them taut.
5.
Represent the parts of the DNA molecule as follows:
Phosphate – straw (color #1)
Deoxyribose sugar- plastic beads (color #1)
Adenine – (straw color #2)
Guanine – (straw color #3)
Thymine- (straw color #4)
Cytosine-(straw color #5)
You will need to decide how long each straw segment should be to best fit your model.
6. Construct the backbone of the DNA model by threading phosphates (straw
color #1) with alternating Deoxyribose sugar (plastic bead color #1) on the
two vertical pieces of string.
7. Using the key in step 5, construct the horizontal rung part of the ladder with pairing nitrogen
bases. On one piece of pipe cleaner thread 2 bases (a base pair). Remember that Adenine –
(straw color #2) always pairs with Thymine- (straw color #4) and Guanine – (straw color #3)
always pairs with Cytosine-(straw color #5). Next, attach the pipe cleaner directly above the
sugar bead on both sides of the model (so that it looks like a ladder rung).
8. Continue the process until the “ladder” is complete with at least 5 horizontal rungs of both A=T
and G=T. Then twist each side of the ladder counterclockwise two complete turns or until the
desired twisted double helix is achieved.
9. Carefully place the two threads through the two open holes in end B from the inside of the box
to the outside. Tie the strings to each other in a knot.
10. Construct a key to identify the parts of your DNA model. On a separate piece of construction
paper or the side of the shoebox, glue the colored bead used for the sugar and label it
Deoxyribose sugar. Do this for all parts of your model.