Biology Learning Target 6

DNA MODEL KIT – using the manipulative provided, student pairs will create a model of the DNA molecule to fully appreciate the structure and how it relates to the function of the molecule. The structure of the DNA molecule plays a crucial role in holding the instructions of an organism and in transmitting the information to the other cell parts so that the cell functions properly.

Materials needed:12 - red adenine12 - yellow thymine12 - blue cytosine 12 - green guanine1 continuous gray backbone that represents the sugar + phosphate molecules12 single gray sugar + phosphate pieces

Procedure: 1. Build your DNA model based on the following

partial code for hemoglobin, a protein that is responsible for transporting oxygen in the blood stream. The actual code is 626 base pairs in length!

A T G G T G C A T C T G

2. Create half of your model by attaching the bases shown above to one of the continuous gray backbones. Remember, the base always attaches to the sugar molecule, deoxyribose found in DNA. You have now made one side of the double helix structure.

Note: carefully pull the base through the DNA backbone until flared ends pop through.

3. Next attach the complementary bases to the single helix and connect the single gray pieces to form the opposite side of the double helix structure. Remember, the sugar and phosphate molecules alternate along the backbone or sides of the DNA molecule. You have now made a complete DNA molecule and it should look like a ladder.

A T

G C

Biology Learning Target 6

4. To create the double helix, rotate the bases so that they are vertical instead of horizontal as shown to the right. The bases should resemble the steps of a ladder when positioned correctly.

5. With your right hand on the top base pair and your left hand on the bottom base pair, twist your hands in opposite directions until the DNA backbones touch each other in a tight coil.

6. Release the bases and allow the model to relax into its double helix shape. Have your teacher check your model.

7. DISASSEMBLE once your teacher has checked your model.

Biology Learning Target 6

Name: ___________________________

DNA Model Conclusion Questions

1. What are the complementary base pairs for the DNA sequence below?

A T G G T G C A T C T G

____________________________

2. What two molecules make up the sides of the DNA ladder?

3. What molecules make up the steps of the DNA ladder?t

4. List the 3 parts of the nucleotide. What parts of the DNA model represent each part of the nucleotide?

Parts of the Nucleotide Sketch of the part of the DNA model

5. In human cells, DNA is approximately 6 feet in length. After creating the DNA molecule, explain how DNA is able to fit inside the nucleus of a cell.