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Molecular Model

From the DNA Kit Program Manual

Equipment and Supplies

Model pieces
Paint
Instruction guide

Activity set-up

1. Follow the instructions for construction of the model
2. Paint the model before using it in public demonstrations

Things to think about when using this activity

• This model should be assembled by staff , volunteers or better yet through a classroom activity. It is an elegant, yet relatively sturdy model that demonstrates the fine chemical structure of DNA. Volunteers and staff can use this model to initiate thought provoking instructions about DNA structure, function and analysis.
  
  
• Once the model is assembled, it cannot be stored in the program trunk, Before assembling the model, think about where it will be stored before it is completed. Because of its more delicate nature, we do not recommend placing it in an unsupervised area, otherwise you will be spending a great deal of time repairing your DNA structure.

Questions that may come up about these activities

How long is DNA?

If the DNA inside one cell was stretched out end to end, it would be approximately six feet long. It is estimated that an adult human has 60 trillion cells. That is a lot of DNA!

It is estimated that the human genome (that's all of the DNA in one cell) contains roughly 3 billion base pairs. If you construct a DNA model out of pop beads containing 12 bases pairs (or rungs of the ladder) it is approximately one foot long. If you constructed a model representing the entire human genome using pop beads, it would have to be 250 million feet long, or 47, 348 miles long. One fun activity to add to the DNA modeling station would be to represent this length using string and a map. Chromosome 1 is thought to contain 263 million bases pairs - 263 million base pairs/12 base pairs per foot = 22 million feet or 4150 miles. This is approximately the distance across the entire United States.

Make and Take Ideas

This is a protocol from a 7th grade science teacher - (Kris Swartchick, Wayzata Central Middle School, Wayzata, MN). We have included if you want to have an activity allowing visitors to take something home. It is relatively inexpensive and easy to do.

Supplies Needed

• Two 24-inch pieces of fishing line or string
• Eight 2-inch pieces of blue chenille stems (pipe cleaners)
• Eight 2-inch pieces of yellow chenille stems
• Eight 2-inch pieces of red chenille stems
• Eight 2-inch pieces of green chenille stems
• Eighteen pieces of dried pinwheel pasta
• Sixteen pieces of dried ziti cut pasta

Step-By-Step Instructions

1. Tie the end of a string onto a piece of pinwheel pasta.
2. Thread the string through a piece of ziti pasta followed by another piece of pinwheel pasta.
3. Continue alternating ziti pasta with pinwheel pasta until you have nine pieces of pinwheel pasta and eight pieces of ziti pasta.
4. Tie the string onto the last piece of pinwheel pasta so the pieces do not come off.
5. Repeat the procedure with the other piece of string.
   The pasta strung onto the two lines represent the sugar-phosphate backbone of DNA.
6. Lay the two pasta strings side by side.
7. Using one of the pasta strings, twist the ends of the chenille stems onto the pinwheel pasta.
   You can add the chenille stems in any combination you want, creating your own genetic code.
8. Repeat with the other strand, adding the colors on the opposite strand using the following base pairing:
   Adenine (red) always pairs with thymine (green)
   Guanine (yellow) always pairs with cytosine (blue)
9. Twist the ends of the chenille stems together creating the rungs of the DNA ladder.
   The rungs of the ladder represent the hydrogen bonds that hold the DNA strands together.
10. Holding your model up, give it a twist to demonstrate the helical structure.

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Last Reviewed: October 22, 2008