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Design your Own DNA Model Molecule

Supplies Needed (per model) 2 white/tan 12” chenille stems (aka “pipecleaners”) 2 colored 12” chenille stems 12 __________ ____(pony) beads (A) 12 ___________________ beads (G) 6 ___________________ beads (T) 6 ___________________ beads (C) 22 ivory or white beads (sugar) 22 black beads (phosphate) scissors ruler

Directions:1. Cut each white/tan chenille stem into six 2 inch sections.2. The pony beads represent the 4 different bases:Adenine (A) - __________________Thymine (T) - __________________Guanine (G) - ___________________Cytosine (C) –____________________3. Because A and G molecules have 2 rings, you will use 2

beads for each of these molecules. Use one bead for T and C molecules, which have only one ring.

4. Thread beads representing an Adenine and Thymine base pair onto one of the 2-inch white chenille stems. (Remember to use 2 beads for A and one bead for T). Prepare 6 of these segments.

5. Prepare 6 Guanine and Cytosine base pairs, using 2 purple beads for G and 1 gray bead for C.

6. Connect one white chenille segment to the colored chenille stem approx. 1 cm from the bottom. Wrap the end of the white stem around the colored stem. Connect the other end to the second colored chenille stem (see photo). This is where you can be creative with the genetic code - you can choose to make your own DNA sequence!

7. On the first strand put an ivory bead and then a black bead. On the other strand put a black bead and then an ivory bead. The two strands actually run in opposite directions and this helps us see the order. After these beads you can put another set of bases on their white pipecleaner.

7. Follow the same procedure for the remaining white segments and beads. Add each consecutive base pair (white chenille segment after the sugar and phosphate beads making sure to keep the black and white pattern running opposite on each side.

8. When all 12 base pair segments have been added to the DNA molecule, you should have a model that looks like a ladder.

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9. To make your double helix, twist your model slightly so the molecule forms a spiral. DNA molecules have a right-handed helix shape that winds in one direction (see diagram on next page). You can figure out the direction by sliding the fingers of your right hand along backbone. If it is right-handed, your thumb should be moving forward while you do this.

10. CONGRATULATIONS! You have created your own unique DNA molecule. The sequence of the base pairs in the DNA ladder is what makes different DNA molecules unique, and is what the Human Genome Project and other genome sequencing projects are all about.

Questions! 1. What beads make-up the backbone (outside edges) of the DNA molecule?

What do they represent?

2. What colors represent the 4 nitrogenous bases?

3. If you cut your molecule in half so that you only had one side of the ladder, could you rebuild the other side? EXPLAIN why or why not!

4. Draw you DNA code (see the example on the board).

5. Compare your DNA molecule to two others. a. How are they similar?

b. How are they different?

c. Is it possible that these four bases (A,T, G, C) are responsible for making all life as we know how? How?

6. Explain how your DNA molecule would be replicated.

7. Transcribe one strand of your DNA molecule into RNA.

8. Translate the mRNA into a protein.

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9. What does DNA stand for?

10. How does damage to DNA lead to problems for the organism? In other words, what does DNA do?