carrier proteins are actually involved check this out we have carrier proteins involved in active transport and we have carrier proteins that are involved in diffusion and facilitated diffusion so what is a carrier well these are the guys that I drew that I draw them like this because I envision if this is my cell membrane this is one carrier so this is moment one that I have a carrier that is open to the extracellular fluid and here is the intracellular fluid and then at moment two for some reason the carrier has a conformational change a shape change oh geez and now the carrier is open to the intracellular fluid you can imagine that if I had a substance like this substance right here it's actually the binding of the substance to the carrier protein that initiates the shape change the shape changes the conformation changes and then the conformation change literally dumps changes where the opening is the opening started to the extracellular fluid molecule bound shape changes now the opening is to the intracellular fluid and the molecule falls off we've now transported the molecule from the extracellular fluid into the intracellular fluid once the molecule falls off usually this shape will go back to its original conformation because that molecule isn't attached to it anymore in its original conformation it waits for another molecule and this is something that I don't know I find it like this class is so cool the fact that these molecules literally molecules sticking together cause molecules to change shape and it's the shape change that enables function it's the change in the structure that affects how that molecule is actually going to function in the body a pattern that we will see over and over again because that's literally how everything works now if you know that molecules that these carriers can enable facilitated diffusion or active transport what is the difference like how are you going to know if this is facilitated diffusion or active transport there's one easy peasy way of knowing are we pumping molecules against the concentration gradient or are we pumping them with the concentration gradient okay so I'm going to make this into either passive I mean facilitated diffusion or active transport are you ready um this is what I'm doing this is like this okay did we pump that thing with the concentration gradient or against the concentration gradient so higher concentration in the intracellular fluid we moved a particle from the extracellular fluid into the intracellular fluid that's against the concentration gradient we're pumping something into its higher concentration zone which means that has to be an example of active transport active transport is what we're talking about next