Science Bus 5/1/07-5/2/07
DNA
Objective:
Learn about DNA’s role as nature’s blueprints.
Materials:
String or wire
Beads (4 colors, lots of beads)
Plans (i.e. a sheet with a particular feature: hands with opposable thumbs, paws,
hooves, fins, wings, tail, scales, fur, feathers, skin, gills, lungs, normal eyes,
compound eyes, antennae, teeth, fangs, beaks, baleen, etc.)
Candy DNA model (NOT for eating, it tastes gross anyway)
Paper and markers for drawing
Pictures of genetically modified plants + Dolly the sheep
Discussion:
Talk about how people would build something from a set of plans.
How are the instructions represented?
How do the plans themselves get copied?
How does this relate to living creatures?
Genetic engineering and you: show pictures of genetically engineered plants
designed to be resistant to disease, larger than normal, seedless, etc.
Show a picture of Dolly the sheep. How is Dolly special?
Activity:
Part 1: DNA Model
Show the kids the DNA model made out of spicy drops. No they can’t eat it; they
wouldn’t want to anyway the candy is disgusting. The color code in the model is:
white = (ribose) sugar, purple = phosphate links, red + green = adenine +
thymine, yellow + orange = guanine + cytosine. How can the blueprints for life be
only composed of 4 letters? (How can computer data be only represented by 2
“letters?”) If you can, talk about the pairing and how this allows for easy copying.
From this point on DNA will be represented by just a single strand of wire with
beads of 4 colors. Point out that with only one strand you can figure out the other
side of the double helix. You could also mention that in order to make proteins
your cells will only copy half of a DNA (double stranded) section into RNA
(single stranded).
Part 2: Match the animal to its DNA
Provide a chart that matches up the body parts with DNA. Start with normal
looking animals and progress to increasingly wacky ones. The kids have to figure
out what kind of DNA sequence will generate that kind of animal.
Part 3: Transcription + Mutation (Telephone)
Provide one long sequence of beads on a wire for each table. The kids take turns
copying the sequence but they have a limited time to do so. The next kid can only
look at the copied sequence not the original. Rinse, lather, repeat. See how close
the final sequence is to the first. Talk about how this gives rise to new species.
Part 4: Design your own genetically engineered animal.
Before the kids had to match up the DNA of the animals to the body parts, now
they can put together whatever kind of animal they want. Provide the paper, the
markers, and beads and wire. Ask them to create a DNA sequence and then draw
what they think their animal would look like.