Download BIOLOGYTHE DNA DOUBLE HELIX MODEL

BIOLOGY
THE DNA DOUBLE HELIX MODEL
Introduction: In this activity, you will be constructing paper models of the DNA structure
Watson and Crick proposed in 1953. As you construct the models, look carefully at the
chemical bonds between the nitrogen bases (A, G, C, T) with the phosphate and sugar
molecules. Different members of the group will be constructing different DNA models and
later you will compare the different models.
Materials:
Nitrogen bases:
Adenine
Guanine
Thymine
Adenine
Tape /glue/ staplers for fastening base pairs together
1 m string/ yarn
2-3 drinking straws cut into 2.5 cm pieces to serve as “spacers”
Paper clip straightened
Procedure:
1. Your class will work in eight different groups, each group building a different portion of
DNA from either molecule 1 or molecule 2.
2. Each group will be given model pieces of the nucleotide base pairs.
3. Cut out the model pieces around the outer solid black lines.
4. Make a slit on the faint dotted lines on the right hand side of the model where the
nitrogen bases are found. This serves as the hydrogen bonds holding the bases together.
5. Connect the nitrogen bases by inserting through the dotted lines, with one base on
your left hand side up and the nitrogen base on your right hand, face down.
6. Use glue or tape to stabilize the connection. Put a hole at the middle of the
connection marked with “x”. This is where the string will go through and a spacer to be
placed in between.
7. Fold on the faint dotted lines on the left hand side of the model pieces with the O=P-O
folded up and the unmarked half folded down.
8. Using a straightened paper clip, insert the string in the middle, add a “spacer” and
connect your pieces together. Secure the string by tying on one side while you
continue to string the rest of the pieces together.
9. Now you are ready to glue/staple/tape the folded left side of your model. With the
O=P-O folded up, connect it with the folded side down of another piece. Do the same
on the other side of the model.
10. Continue until all of your pieces are connected together. Tie securely the other end
when all are connected together.