Name _______________________________________ Date ____________________

DNA Structure and Replication

Purpose: To determine the structure of a DNA molecule and to explore how DNA replicates. In this lab you will create a 2-dimensional model AND a 3-dimensional model of DNA.

Materials: 2-D paper model pieces: 4 Adenine (A), 4 Cytosine (C), 4 Guanine (G), 4

Thymine (T), 16 phosphates, 14 sugars 3-D paper model blueprint

Background:1. What is DNA?

2. What is a nucleotide? What three pieces is a nucleotide made of?

3. What pieces make up the backbone of DNA?

4. What are the 4 nitrogenous bases?

5. Which bases pair together?

Procedure:Part A: 2-D Model

1. Cut out the 2-D model pieces.

2. Color the nucleotide bases the following colors:Adenine (A) – pink/red Cytosine (C)– blueGuanine (G) – green Thymine (T) – yellow

3. Assemble your DNA strand. There is more than one correct way to do this, but there are also wrong ways! Make sure your backbone and bases are built correctly.

4. Glue your assembled 2-D strand to a blank sheet of paper.

5. Cut your 2-D strand in half down the middle (Write your name on both half-sheets). Trade your half-sheets with 2 different partners.

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6. Rebuild the two half-DNA strands you have by writing in the nitrogenous bases for each complementary strand. Write your initials on the half-sheets.

Part B: 3-D Model1. Cut out the 3-D model template.

2. Label and color the template to MATCH your 2-D model.

3. Follow the instructions below to fold the template to create a 3-D model of DNA.

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Analysis and Conclusions

1. Look at the 2-D strands your classmates have created. Are they the same as yours? How do you think this observation can compare to the structure of the DNA we have in our bodies?

2. Describe the structure and appearance of your 3-D model. Is it what you were expecting?

3. Compare and contrast your 2-D and 3-D models. How are they similar, and different? Which one is easier to work with? Which one is more accurate? Why?

4. Were you able to REPLICATE your partners’ DNA strand? Why/why not?

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