Name: _________________________________________________________________________
DNA Modeling
Objectives:
 To learn the names of the four different nucleotides making up a DNA molecule
 To construct a model of DNA, including the sugar-phosphate backbone, and the purinepyrimidine base pairs.
Materials:
 Cut outs of basic subunits of DNA
 Colors
 Scissors
 Glue
 Copy Paper
Procedure:
1. Decide which colors you want to use as your sugar, phosphate and 4 bases. Write the
colors on the back of this sheet.
2. Color code the nitrogenous bases, phosphorus and sugars according to the colors you
decided.
3. Cut out all of the nucleotides.
4. Glue 8 nucleotides together to assemble one strand of the DNA molecule going down
the left side of the copy paper.
5. Complete the complementary strand, by assembling the right side of the molecule by
adding the complementary base to make the pair. You will need to turn them upside
down in order to make them fit. This is because DNA strands are antiparallel, they run
in opposite directions.
Your finished model should look like a ladder.
1. What colors did you use?
Sugar: _______________
Phosphate: ___________
Thymine: _____________
Cytosine: _______________
Adenine: ________________
Guanine: ________________
2. What are the three parts of a nucleotide? __________________, __________________,
and nitrogenous __________________.
3. Draw a ball and stick model of a nucleotide and label the three parts.
4. How many nucelotides are present in the model? ____________________
5. What is the proper name of DNA? __________________________________________
6. What is the proper name of the shape of DNA? ________________________________
7. Which molecules make up the “backbone” (sides) of the DNA? _________________ &
_____________________
8. Which molecules make up the “rungs” of the DNA? ______________________________
9. What type of bonds hold the two strands of DNA together? _______________________
10. Which nitrogenous bases are pyrimidines? __________________ & ________________
How many rings are in pyrimidines? ___________
11. Which nitrogenous bases are purines? _________________ & ___________________
How many rings are in purines? ____________
12. Which base always pairs with adenine? ______________
How many bonds are between these two bases? ___________
13. Which base always pairs with adenine? _____________
How many bonds are between these two bases? ___________
14. If 30% of a DNA molecule is Adenine, what percent is Cytosine? _________________
15. What scientists discovered this structure?