All cell membranes have proteins embedded in them. Each protein has its own job.
Students often draw the proteins in the cell membrane them like this:
With more detail we can see that proteins are three-dimensional machines, with movable parts.
Adding more detail, we can now see molecules going in and out of a cell. The membrane proteins open or close as needed to let certain molecules in, and other ones out.
Here, a student in our class build a three dimensional model of a membrane protein. He made one monomer; and then attached several of them to make a polymer.
Instead of attaching eight monomers in a straight line, he’ll form them into a circle:
This becomes a model of a protein that floats in a cell’s membrane,
It can have two shapes, closed or opened, depending on how it’s folded.
It allows certain molecules in or out of a cell, as needed.
For instructions we may refer to a video from AskABiologist:
Proteins are made of building blocks called amino acids, and have their own special shape. Not only do they look different, but they have different jobs to do inside the cell. Some proteins help move things around in the body, others act like support structures or glue to hold parts of the cell together, and some can help reactions in the cell go faster. The protein we’re making is a channel that sits in the outer cell surface, or membrane, and works like a door that lets certain molecules pass through. Some channels are open all the time while others can be closed depending on signals from the cell or the environment.
Narration by Rebecca Elaine Ryan
Original origami design by Florence Temko
Here’s the video from AskABiologist
8.MS-PS1-1. Develop a model to describe that (a) atoms combine in a multitude of ways to produce pure substances which make up all of the living and nonliving things that we encounter, (b) atoms form molecules and compounds that range in size from two to thousands of atoms, and (c) mixtures are composed of different proportions of pure substances.
HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
Disciplinary Core Idea Progression Matrix: PS1.A Structure of matter: That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact, states of matter, phase changes, and conservation of matter.