You Are What You Eat: Food, Biomolecules, and the Carbon Cycle

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SWBAT describe that cells build large molecules required for cell functions and that large molecules in food are broken down into smaller molecules by cells to provide energy or building blocks.

Big Idea

Cells and organisms must exchange matter with the environment. Carbon moves from the environment to organisms in order to build carbohydrates, proteins, nucleic acids, and/or fats.

Learner Goals

Note: I recommend that you first check out this resource in order to get the most out of this lesson!

In high school I took several drafting classes and, for a while, I had hoped to become an architect. With respect to planning instruction and teaching, I feel that I can still live out the detailed approach to building something intricate and complex even though the product is a lesson rather than a certain "built environment".

The lesson-planning document that I uploaded to this section is a comprehensive overview of how I approach lesson planning. This template includes the "Big Three" aspects of the NGSS standards: Disciplinary Core Ideas, Crosscutting Concepts, and Science Practices. Of course, there are many other worthy learning goals, skills, instructional strategies, and assessments that can be integrated into a class session. I don't feel compelled to check every box but, rather, use it as a guide to consider various options and tailor the lesson in light of these.

With regard to this particular lesson students will be able to: 

1. explain how cells and organisms must exchange matter with the environment. For example, water and nutrients are used in the synthesis (building) of new molecules. Carbon moves from the environment to organisms where it is used to build carbohydratesproteinsnucleic acidsand/or fats

2. describe that cells build large molecules required for cell functions from smaller molecules (i.e., proteins from amino acids, carbohydrates from simple sugars, fats from fatty acids, DNA from nucleotides). In other words small molecules (monomers) make large ones (polymers).

3. describe that large molecules in food are broken down into smaller molecules by cells to provide energy or building blocks (i.e., proteins into amino acids, carbohydrates into simple sugars, fats into fatty acids, DNA into nucleotides).

I hope you get some value from my work! Please find the more intricate details of this lesson plan there.

Anticipatory Set ("Hook")

15 minutes

1. As this lesson starts to unfold (as is my typical approach), I clarify the meaning of key vocabulary that will be encountered in the lesson. I post vocabulary to a Word Wall (AKA a SMART board in my case) and quickly (verbally) identify and define their meaning (especially in light of the lesson). Academic vocabulary can be particularly challenging for students, especially ESL students so this begins to set all students up for success by increasing access to the meaning of biology terms.

Watch this video to learn more about the "Word Wall" technique!

At this time I articulate the three learning goals for the lesson and direct students to mark the lesson pre-/post-assessment form form to indicate their initial level of understanding.

2. Next, designated students (i.e. "Team Leaders") choose several food items from a wide variety (canned vegetables and fruits and boxed goods). Students will then examine two nutrition labels and compare and contrast their ingredients. They are to complete the You Are What You Eat document

The following videos demonstrate my techniques for "dividing and conquering" the necessary class logistics via a "Team Roles" approach as well as for using class time for the greatest impact as seen in "Online Stop Watch".

3. At the end of this lesson section, I randomly call on students to quickly identify the foods that they examined and share several common features of the chosen food items. The point here is for students to realize that all foods contain a limited group of nutrients (fats, cholesterol, carbs, etc.). The next step is to determine what each of these nutrients (i.e. biomolecules) are made of and to discover how important carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulfur are to building monomers and, by extension, polymers.  

Instructional Input/Student Activities

35 minutes

The relationship between monomer and polymer is essential to understanding metabolism. I explain the difference between "catabolism" (the breakdown of food molecules during digestion) with "anabolism" (the building of new molecules used for cell functions). These questions will guide students as they examine the structural formulas of each biomolecule type:

  1. "What patterns do you see in their structure?" 
  2. "Which element(s) seem(s) to be most essential to building these molecules?"
  3. "How do we obtain these necessary elements and what are the respective functions of each monomer?"

The overarching goal is for students to recognize that, through eating, we obtain raw materials (elements) in our food that (through digestion) create the necessary pool of building blocks that enable our cells to make new molecules (proteins, for example). So literally, we are what we eat. As a human body system, we are connected to our ecosystem and related food web through the input of food and output of waste products. At any level of organization (cells, tissues, organs, etc.) this exchange of matter is essential for proper health (dynamic homeostasis).

As students examine the four pages of the packet, I direct them to color-code each element (e.g. carbon=green and oxygen=red). Having done this, it should be readily apparent which elements are present and their relative proportion in each biomolecule. Plus coloring is loads of fun and makes pattern recognition all the easier!


Closure: What did we learn? Where do we go from here?

5 minutes

Each day students and I zero in on the target goals for the lesson and do a pre- and post-assessment at the beginning and end of class. At this stage of the lesson, I direct students to return to these goals and self-assess their understanding of the three goals for this lesson (compared to their initial self-score). In this way, students are practicing good metacognitive awareness. Ideally, if a student marks a B or a C at the beginning of class, they show a progression toward a B or an A. In doing so, students identify areas to revisit prior to the summative assessment!

Furthermore, I want to regularly provide a few moments at the close of each lesson to get a sense of what students have taken away from our shared time together.

Watch this video ("Learning Goals and Self Assessment") to see how I articulate rigorous and student-friendly goals in order to lead students to investigate, communicate, and create!

In these two clips you will see how I equitably choose students to respond to prompts ("Random Draw") and one strategy that I use to capture student understanding ("Fill in the Blank").

Lesson Extension & Follow-Up Activities

Now that students have examined the nutrition labels of two food items (a macro analysis of polymers) and examined the composition of biomolecule structures (a micro analysis of monomers), I point them to the much larger macro level (ecosystem and food webs) as they look at the flow of carbon in an ecosystem. Knowing that carbon, more than any other element, is crucial to the building of biomolecules and key cell structures, they are to consider the ramifications of a disruption to the food chain and/or food web to which organisms belong. The Carbon on the Move Exit Task should be done for homework. In doing so, they should reasonably predict that biomolecules can't be made (anabolism) if the necessary input of nutrients (and their elements such as carbon) are not regularly supplied.

Organisms are what they eat, therefore if they eat too little or fail to eat the right foods, they will literally suffer for it. 

I hope that this will be an important A-HA for my students since I know that proper nutrition is a struggle for many. I see too many students eating a bag of potato chips for breakfast!!