In biology, DNA is the blueprint, but it is proteins that are the workhorses of the cell. For the most part, proteins are the components that actually “do” something. They catalyze reactions, give the cell structure, communicate information, haul cargo, and help the cell move.
The idea that proteins can assemble themselves is a difficult one for students to grasp. First, they have to understand that proteins are encoded by a particular sequence of amino acids (genetics, central dogma, cell biology). Next, they need to know that these amino acids interact in particular, semi-predictable ways (biochemistry). Then, the students have to learn that structure determines protein function and changes in structure can alter function (more biochemistry). This combination of details makes proteins a very difficult subject to discuss, particularly with novice students.
Skylar Tibbits gave an excellent TED Talk that can help introduce the idea of “self-assembly” to students. In this talk, Tibbits shows videos of objects made of plastics, such as ones you would obtain from a 3D printer. The difference with Tibbits’ objects is that after they are made, they change conformation on their own. These materials are “pre-programmed” to transform in response to heat, time, or different solutions. The conformational changes almost look like a trick, but as Arthur C. Clarke said, “any sufficiently advanced technology is indistinguishable from magic.” That’s exactly what cells are – a 3.7 billion-year-old technology.
I would recommend first introducing students to translation and protein structure (primary, secondary, tertiary, and quaternary). As you prepare to show the video or assign it for homework, preface it by making the connection to protein self-assembly. These are some possible guiding and reflection questions for students:
- What is “self-assembly?” If all products where manufactured to self-assemble, how would that change how factories work? Can you think of examples from your everyday life of objects that you would like to see self-assemble?
- What is a benefit of self-assembly for cells? What sort of systems would a cell have to possess if proteins did not self-assemble?
- What about a protein determines how it functions? Is this true for proteins that act as enzymes?
- What features of a protein do you think enable it to self-assemble?
- Would a protein that normally exists embedded in the plasma membrane self-assemble in the same way as a cytosolic protein?
After introducing protein folding and function in this way, you can follow up by showing students this popular video from Harvard: The Inner Life of the Cell. In the video, ribosomes produce proteins that self-assemble and later have particular roles in the cell. Both of these videos can help students understand these complex topics using excellent images of these processes in action.