Friday, January 23, 2015

Protein Synthesis Cookies Activity

This was probably our very favorite of this unit's activities. It was fun and it just seemed to really cement the idea of how proteins are formed into the children's memories.

An overview: In this activity, each pan with cookie dough in it is like a ribosome, where the synthesis of proteins takes place. The long chain of code on your paper is a strand of mRNA that codes for a specific protein. Each cookie topping is analogous to a different amino acid. Your hand (I guess?) is like the tRNA that goes and finds the right amino acid floating around in the cytoplasm and carries it back to be placed into the amino acid chain. And, when you are done placing all the toppings in the right order, the chain is analogous to a protein that can be released into your body to build tissue or carry out various other tasks.

And more background:

Now. Here are the instructions. First, pre-activity preparation. You need to make a code-breaker sheet for each child. This will show which codons (or sequences of three bases) "code" for which amino acids (represented here by the various toppings—chocolate chips, peanut butter chips, marshmallows, etc.). Besides codons for amino acids, you need a start and a stop codon. Just so the children would know them, I used the actual codons for these that our bodies use--AUG for "start," and UAG (among others) for "stop." Then I just made up the other codons. Here was our "code":
  • AUG—start
  • AGA—chocolate chip
  • GCC—peanut butter chip
  • AGC—white chocolate chip
  • UGU—sprinkle of cinnamon
  • CUG—sprinkle of coconut
  • AAA—chocolate kiss
  • CCA—peanut
  • GGU—sprinkle of rainbow sprinkles
  • AUU—marshmallow
  • UAG—stop

Next, write out the sequence of bases for each "protein." (Remember, proteins are chains of amino acids.) I made a different protein for each child (with a shorter one for Daisy to make it a bit easier for her). I included a sequence of "nonsense" at the beginning of each protein, representative of all the RNA that doesn't code for proteins in our chromosomes. I put in some nonsense at the end, after the "stop" codon, too.

I also made an answer key for myself, listing what the finished protein should look like for each child, so I could quickly check their work. (So for example, "3 chocolate chips, white chocolate chip, sprinkle of cinnamon, peanut, marshmallow, two peanut butter chips.")

And then, of course, you need to make your cookie pizza dough, and gather a bunch of different toppings. Here's the recipe for cookie pizza. We love it.
So, to do the activity, each child starts with a small pie pan and a handful of cookie dough. Press the dough into the pan about 1/2-inch thick. (Of course, you can press your dough in circles straight onto a cookie sheet, or even make a whole cookie pizza and let each child make his protein on a different section of the pizza. It's just easier for everyone to work at once when you use separate pans.)
Then, each child should look at his section of RNA code. Have him scan the sequence until he finds the start codon (AUG in our case). Circle the start codon. Then, with a pencil, make slashes or commas between each group of three bases after the start codon. (Don't divide the bases into groups of three before finding "start," or you might make your divisions in the wrong places and get totally different amino acids than you're supposed to! This does happen sometimes with DNA or RNA—it's called frameshift and can happen if a base is wrongly inserted to or deleted from the gene.) When you get to the stop codon, stop.

The next step is just transcribing each codon into its respective amino acid. So, with our example, if you saw "AGA," you would get a chocolate chip and place it onto your cookie. Line up the amino acids in the correct order, you can curl them around in a spiral or a wavy line if they won't fit in a straight line across your cookie (and this, too, is analogous to real proteins, as each protein has a specific shape which helps it do its job). When you get to a stop codon, you are done. 
Then bake your "protein" at 350 for 8 minutes or so (for small individual cookies) or 15-20 minutes (whole cookie pizza). Remove from oven when edges are just starting to brown. Cool and eat!
We had some extra dough, so we made a full cookie pizza also. We just let each person decorate a piece however they wanted to, but you could also do your mRNA transcription on a section of the pizza if you wanted to.

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