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| 3 RuBPs each ready to have a carbon fixed to them |
Even in my fourth year of teaching the new AP Biology curriculum, I'm still tweaking the class to help my students have a deeper understanding of the concepts. We are just finishing up our energetics unit. I've blogged here about the diagrams we work through as a class for cellular respiration and here for photosynthesis.
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| Rubisco doing its job of carbon fixation |
Last year I found this youtube video of Kevin Lam explaining the Calvin cycle. I find the kids often struggle with the Calvin cycle since 3 of the cycles are actually happening together to get one G3P (which we call a baby sugar). I loved the visual way this video showed carbon fixation and the process of rearranging molecules to recycle RuBP.
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| Molecules are split and ready for ATP and high energy electrons |
I was all set to buy styrofoam balls to do this and then started wondering if I could do this demonstration without lots of styrofoam. I keep a large supply of tennis balls that we use to represent protons in oxidative phosphorylation for both photosynthesis and respiration. I also happened to have a partial box of dominoes and several adhesive Velcro dots. I decided our tennis balls could do double duty and be carbon molecules for the Calvin Cycle and the dominoes could represent the bonds between them.
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| One G3P (baby sugar) is ready to leave |
What I didn't show was the phosphates added to the molecules from ATP (although we did talk about it) or the high energy electrons used in the bonds (again just talking about it), but maybe next year we'll add those in.
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| The process of recycling RuBP begins |
One student was rubisco and fixed the carbon from carbon dioxide to RuBP, another student was the enzyme to split the molecules into 3 carbon molecules, and anther acted as the enzymes to help recycle the remaining molecules back into RuBP.
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| and keeps going |
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| and going, until... |
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| all three RuBPs are recycled and ready to go again. |
