Shuffle and Share
Teacher dialogue
“By itself, a gene can never carry on the processes that our body needs to survive. Just as a complex machine, such as an automobile, is a combination of many smaller, simpler machines, our bodies are a combination of many smaller working parts. Among the smallest working parts are the genes, which are present on each of 23 chromosome pairs, which are contained within every cell of our body. The 50,000 to 100,000 genes that are located on each of the 46 chromosomes can be combined in countless ways to produce many, many combinations.”
Activity
Obtain two decks of cards, each deck a different color. Begin with two cards from each deck. Work with the children to see how many ways the four cards can be combined. Add two more cards and do the activity again. Keep adding cards and coming up with more combinations. This can be done in smaller groups, with each group recording their results and comparing with other groups.
Finally, recombine each 52 card deck separately. Shuffle each deck. Divide each deck in half, and then use half of each deck together. Shuffle these cards together and record the combination. If you have enough cards, work again in small groups, to come up with many combinations using only 27 each of two different decks of cards. Challenge each group to record their ourcomes by making a chart of their results.
Chain of Codes
Teacher dialogue
“The main difference between living and non-living things is that living things use information to create and maintain themselves. Rocks and rain contain no information on how to be rocks and rain. The same is true of the desks, chairs, and computers in our classroom. But all of our pets do contain information on how to be pets, and our bodies contain important information on how to stay alive and well.
Information is a way of comparing one thing with another. We get information from the letters of the alphabet. People who play an instrument get information from sheet music. The information for our bodies is encoded in our genes. The message in genes is read by machinery in our body that makes the parts that work together to create us! It works very much like a cook who follows a recipe to make dinner. The activity that we are about to do shows how a chain made up of different symbols can store information.”
Activity
Trace the following patterns onto red, green, blue, and yellow construction paper. Direct the children to cut out as many of each shape as they have time to. After many shapes are made, take all the yellow shapes and line them up on a table. Help the learners to understand that this simple chain does not tell much of a story, because it does not contain variety in its pattern. Next, randomly add the other three colored shapes to the chain. You might do this by putting all of the childrens’ shapes into a can and pulling them out randomly, one at a time. Explain that the various sections of the chain are directions for a recipe. Even though there are only four simple shapes and colors represented here, they send a message that says, “Take this, add this, then add this....stop here, etc.”
Note that these same shapes can be saved and used for a future activity that will illustrate how the four nitrogen bases fit together.
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GACT Necklaces
Teacher Diologue
Just like the letters in the words that we read and write with in school are our language, the four elements of DNA, called nitrogen bases, are the language that our bodies use to make protiens. These four nitrogen bases are called adenine (A), guanine (G), thymine (T), and cytosine (C). They are arranged like a twisted ladder, or a spiral staircase. The sides of the twisted staircase are made of sugar and phosphate. We are going to make a model of this structure that we will be able to wear as a neck chain. Remember, the real DNA is so small, that we would need a very powerful microscope to see it!”
Activity
Obtain a large amount of ziti to represent the sugar and phosphate groups. Color half of the ziti orange to represent the sugar. Leave the rest of the ziti white to represent the phosphate groups. Now you need to get colored beads, the kind that look like clear colored plastic with the large hole. Make sure you get several bags of each color, enough for each child in the class to make a necklace. You will also need a piece of string for each child, about 6 times as long as the length of the final necklace. Be sure to use the type of twine that will not fray while the children are threading it through the beads and ziti. Use the following threading pattern to string the necklaces, demonstrating the proper combination of nitrogen bases. Use the following key, which should be posted in the front of the classroom.
Adenine-yellow combines with Guanine-blue.
Thymine-red combines with Cytosine-green.
Begin threading with a nitrogen base pair, and then add a sugar and a phosphate to each end. Then thread both ends of the string in opposite directions through another nitrogen base pair. Take those two ends individually and add a sugar and a phosphate to each strand. Repeat until the chain is the desired length. Take the entire strand and twist to show the “spiral staircase.” Tie the ends tight to make a necklace that is also a model of DNA.
(figure available in printed form)
“Bond-Sponge Bond!”
Teacher dialogue
We have been learning that DNA is a double chain of one pattern of elements (necleotides) that is pair with another chain of elements. The base parts of these four elements, which we mark A, T, G, and C match up in pairs. These pairs, when fitted together, have exactly the same width. There shapes and chemical make-up are such that A only fits with T and G only fits with C. So the pattern of the nucleotides in one chain of DNA will match exactly its’ opposite set. The two chains will also be exactly the same distance apart. For example, if the pattern on one side is G-T-A-C-C, the pattern on the other side is C-A-T-G-G.
If the bond is too tight, however, then the DNA chain will not be able to come apart when it needs to, in order to make more, or replicate, itself. We are going to make a model out of sponges that will show us just how this bond works.”
Activity
Enlarge the patterns for the “Chain of Codes” activity. Use a marker to trace the patterns onto sponges colored yellow for adenine, red for thymine, blue for guanine, and green for cytosine. Any sharp pair of scissors will easily cut through the sponge material. This is a good activity for groups of four students. Have the children practice putting the nucleotide shapes together and taking them apart. Remind them that it is important for these nucleotides to come together and break apart easily.
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(figure available in print form)
These are the patterns for “Chain of Codes” “Bond-Sponge Bond!”
Observing the Growth of Mutant Corn Seeds
Teacher dialogue
“Now that you know about how DNA is a recipe for life, we are going to do an activity that will show what can happen when there is a mistake in the DNA code. Remember, all living things have DNA, which is why we will be able to use corn seeds to do our experiment. We will find out what the effect of a mistake, also called a mutation, is on a corn plant.”
Activity
Fill a flower box three-fourths full with potting soil. Use a piece of string to divide the flower box in half across the width of the box. Label the right side of the box “Albino.” Label the left side “Normal.” Plant 10 albino (available from a farmer or from a scientific supply house) and 10 healthy corn seeds in their corresponding place in the planting box. Place the flower box on a table near a window where it will receive direct sunlight. Keep the soil moist. Observe and record your observations every day for three weeks.
What was the total number of seeds which sprouted?
How many albino and how many normal seeds sprouted?
What happened to the plants one week and two weeks after they sprouted?
Describe the difference between the albino plants and the normal plants.
Be sure to explain to the children that both albino and normal seeds were able to sprout, because both seeds contained food within them. However, once the food within the albino seed was used up, these plants would die, since they would not be able to perform photosynthesis.
What is Human Genetics?