Name: ___________________________ Per: ______ #
Exploring DNA Structures
Background Information: DNA is the basic material that contains the information that is responsible for the
way all living organisms physically look and instruction on how to carry out the activities of the cell. We are
going to explore the different parts of DNA.
READ THIS BEFORE MOVING ON:
Before you answer the questions below, complete the following with your DNA “puzzle pieces.”
Lightly color all Phosphate pieces red.
Lightly color all Sugar pieces blue.
Lightly color all Nitrogen Base pieces green.
Then, cut out all your pieces, and write your name and period on the back of each of them. You will
need to look at your pieces and your group member’s pieces throughout the activity.
Directions: Answer the following questions with your group, using the figures provided. You do NOT need to use
complete sentences, unless the question asks you to.
1. Look at your pieces. What are the three different pieces labeled?
2. Compare your pieces to your neighbor’s pieces. Are they all exactly the same? If they are not, what is one
difference between them?
3. Look at the figure below. What are the four nitrogen bases called (write the full names!)?
4. Which nitrogen base(s) do you have?
5. Looking at all of your group members’ pieces. Make a guess about which nitrogen bases would connect to each
other. (Hint: Think puzzle pieces!)
Abbreviate the nitrogen base names by using only the first letter of the name:
__________ matches with __________
and
__________ matches with __________
READ THIS BEFORE MOVING ON:
DNA is a polymer made up of one monomer that is repeated over and over again throughout the
molecule. The monomer of nucleic acids is called a nucleotide. A nucleotide is made up of three
separate pieces: a phosphate group, a sugar, and a nitrogen base. Nucleotides combine to make a
nucleic acid.
6. Have each group member make ONE nucleotide with their three pieces. Connect the pieces that make up one
nucleotide in the order that you think it goes in. Get a teacher signature/stamp
Teacher Signature:
before moving on!
7. Once your teacher has checked your group, have each group member tape their nucleotide together.
8. Now in your group, manipulate (arrange) the nucleotides so that they are all connected in two rows. The
Spokesperson may check with other groups if you have trouble doing so! Once you have connected all your
nucleotides correctly, you will have formed part of a DNA molecule.
9. Sketch a picture of your DNA molecule in the space below.
a. Put a star next to the 2 places your group’s part of the DNA molecule could connect to other DNA molecules.
10. A DNA molecule is often described as a ladder.
a. What parts of a nucleotide make up the sides of the ladder? _________________________________
b. In your picture above, label the sides of the ladder.
c. What parts of a nucleotide make up the steps of the ladder?__________________________________
d. In your picture above, label the steps of the ladder.
11. What do you notice about the direction of the sides of the ladder? HINT: The sides of a DNA molecule are often
described as “antiparallel”. Anti means opposite. Parallel describes two lines that are next to each other that do not
cross.
12. Now bring your group’s DNA molecule to the front of the room and join it to the other groups! We now have one
large DNA molecule!
13. Extension Question: Part of the reason a DNA molecule is described as “anti-parallel” has to do with the direction of
the backbone. Biochemists use the terms 5’ (read: “five prime”) and 3’ (“three prime”) to refer to the “direction” of
the DNA backbone. Using your textbook and resources, describe why the ends of the backbone are referred to in
this way. Include a diagram to explain your answer.r