How to Make a DNA Model With a Mutation
Students can and should build models of deoxyribonucleic acid (DNA) molecules to help them understand how these important components of living systems are structured. Not only will students be able to see and feel how the building blocks of DNA work together, but they can model mutations as well, which show what happens when DNA does not function properly. A common type of DNA mutation, and the easiest to model, is the substitution mutation, in which a single nucleotide--or letter of the DNA code--is improperly substituted for another.
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Things You'll Need
- 2 6-inch pipe cleaners
- 5 2-inch pipe cleaners
- 3 green beads with hollow centers
- 4 red beads with hollow centers
- 2 brown beads with hollow center
- 1 blue bead with a hollow center
Instructions
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Lay the two 6-inch pipe cleaners next to each other and parallel on a flat surface.
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2
Lay the 2-inch pipe cleaners at evenly spaced intervals across the 6-inch pipe cleaners so that they look like rungs on a ladder. Twist the ends of the shorter pipe cleaners so that they are firmly secured to the longer pipe cleaners.
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Assign nucleotide designations to each of the beads. For example, red beads could represent cytosine (C), green beads could represent guanine (G), brown could be adenine (A), and blue could be thymine (T). Recall that each "rung" on the DNA ladder contains two nucleotides bonded together in the center and that C always pairs with G and A always pairs with T--except in the case of a substitution mutation.
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Loosen one side of each 2-inch pipe cleaner so that you can slide beads onto them.
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Slide one red and one green bead onto three of the 2-inch pipe cleaners, then reattach the loose side of each pipe cleaner back to the 6-inch pipe cleaner. These rungs now represent properly bonded C-G nucleotide pairs in the DNA molecule.
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Slide one blue bead and one brown bead onto one of the 2-inch pipe cleaners, then reattach the loose side of the pipe cleaner back to the 6-inch pipe cleaner. This rung now represents a properly bonded A-T nucleotide pair in the DNA molecule.
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Slide one red bead and one brown bead onto one of the 2-inch pipe cleaners, then reattach the loose side of the pipe cleaner back to the 6-inch pipe cleaner. This rung now represents the substitution mutation because it is an improper A-C nucleotide pair, which only happen by accident in nature.
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Once all of the "rungs" of the ladder are firmly reattached, gently twist the entire ladder into the classic DNA double-helix shape. You now have a visual model of a DNA molecule containing a substitution mutation.
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References
- Photo Credit dna image by Allyson Ricketts from Fotolia.com
