If you are teaching about biomolecules, then you are probably going to at least touch on, in part, how they are made. What are monomers? How do they come together to form larger molecules (polymers). I like to start with a very generic overview of the vocabulary and how dehydration synthesis and hydrolysis work to create them and break them apart. This sets up our deep dive into all the types later on in the unit.
If you would like to check out how I first introduce biomolecules, check out the blog post on Carbon and Functional Groups.
I like to review the material from the day before starting. If read blog post linked above, students completed a functional groups worksheet. I would review the answers, ask students if they noticed any patterns in the molecules shown, and then labeled them with the correct answers: carb, lipid, protein, nucleic acid.
Then I tell the students that all of these molecules are simple, and they are used to build larger molecules that cells use. For example, the amino acids, by themselves are unable to do the function of the protein. The cells have to put together a chain of those amino acids, to make the final larger molecule. Once students understand that concept, it's time for vocabulary.
Introducing Vocabulary
Students take all of their notes in a notebook. On the next page, we write down a few things. Here are the notes that we take. In red, I have written some of the questions I ask them or things we talk about while taking the notes.
Before even going into the reactions, see what they already know. Many of my kids have some basic chemistry and they understand how basic bonding works. Once you've discussed basics of bonding, write out the dehydration synthesis reaction. See my notes below.
Have students try to remember what functional group is being shown in yellow. Then ask them how they think you went from two molecules, to the one. How did we end up with just 1 oxygen. Hint: have them look back at the vocabulary word dehydration. Most will see that a water was removed and that the leftover oxygen molecules is sharing electrons between the two monomers. COUNTING bonds is also really important and makes the understanding even more concrete. Oxygen has 6 outer electrons and needs two more, so when the water is removed, the oxygen still needs 2 more bonds to make 8.
Then show them the opposite reaction: hydrolysis. Again, have them think about the word and what it means and look at the overall reaction to see how those two things relate. Here are my notes below.
Dehydration Synthesis/Hydrolysis Game
Before we look at complex molecules, students play a game that uses just the general terms: monomer, polymer, dehydration synthesis, and hydrolysis. This game is short, we play it at the end of the notes (15-20 mint), to reinforce the basic concepts before moving on to the specific groups of biomolecules. I found this game with a simple search of monomers/polymer game on Google. I have re-written the rules a bit and jazzed up the formatting. You can find the game here.
Would love any feedback or questions! What lessons would you like to see next?
Happy Teaching!