Active and Passive Transport

by Jason Amores Sumpter
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transport across membranes can be broken down as passive transport and active transport. Passive transport is the movement of molecules or atoms across the membrane via electrochemical grading. So basically no ATP is going to be expended. Thio have these molecules our Adams move. They will move due to the natural Grady INTs that exist now. A special type of this passive transport is called facilitated diffusion, which is essentially a passive transport where these molecules move across the membrane using protein channels or carrier proteins. Protein channels air trans membrane proteins that form a poor through the membrane that allows specific molecules or ions to pass through. So here you can see we have these two different types of molecules, but Onley these they're gonna move through the poor because these channels are specific thio specific molecules or ions. Now there's a special type of channel you should be familiar with, called aqua por in, and this is a water channel. Now, water is a small enough molecule that it can diffuse through the membrane without any assistance. However, it doesn't diffuse through at the rate necessary to sustain living processes, so organisms use aqua parents to make three passage of water through membranes much, much more efficient. You know, it's it's actually amazing how much more efficient it is. If you look at the numbers now, carrier proteins are a little different than channel proteins. Channel proteins air just like, ah, hole that things can go through To get through the membrane. Carrier proteins have to actually carry a molecule through the membrane so they'll actually bind a molecule on one side, and then they'll change shape. And in that process, they'll actually carry the molecule through the membrane and ejected on the other side. Um, so it's not like a poor, it's it's different. It's almost like a you know, e. I would think of it as like a train moving through a tunnel or something, right, like the the molecule has to board a car, and then it moves through the membrane, and then it's released. Now active transport, unlike passive transport, consumes a teepee directly in order to move molecules or ions across the membrane. Now there's two types of active transport that we classify as primary, active transport and secondary active transport. Primary active transport directly hide relies is ATP to power protein pumps The most famous example of thes pumps is the sodium potassium pump that is used for, like everything. It's everywhere in the body. It's probably the most important pump for you to know. Sometimes it's called Seneca TPS, which is sort of an abbreviated name for it. Now, what this sodium potassium pump is going to do is move three sodium ions and two potassium ions in opposite directions across the membrane. Here, you can see an ACA tapas and action. What we have is these are our sodium ions and they're gonna get loaded up in here. The three of them are going to get ejected on the other side, and that is going thio require some ATP hydrology. Sis, thes potassium ions will get loaded up in here. This phosphate group will be ejected, causing a confirmation. I'll change that. Releases thes to sodium ions on the other side. You don't need to know the specifics of it. I just go through it because, you know, I think it z interesting and can't hurt to know these things. Now. Co transporters are gonna be a type of secondary active transport Secondary active transport is going to harness the potential energy created by pumps so it doesn't itself consume ATP in order to move things. But it uses the concentration Grady INTs set up by pumps that do consume a teepee in order to move substances across the membrane. Now, if you're thinking well, how is this any different from, like passive transport? If they're just both use ingredients? The differences in secondary active transport those Grady INTs have to be actively maintained by pumps. If you shut the pumps off, you would lose secondary active transport as well because they rely on the Grady INTs built by those pumps. So, in a sense, they're indirectly using the at Pia's. Well, now, co transporters are going to, uh, carry out secondary active transport by using one substance to move another substance. So they're gonna move one substance along. It's Grady int, and they're gonna use the energy from that to carry another substance against. It's creating, and this can work in two directions, actually jump out of the way here. So you're gonna have sim porters, which you're gonna move both substances in the same direction. So you can see here we have a sim porter. It's gonna take two things move one along its radiant and the other against its radiant but moving one thing along its radiant will provide the energy to carry the other, uh, molecule er, Adam. Through Now, anti porters are very similar in concept. The only difference is they are going to move the substances in opposite directions across the membrane. But it's the same idea. One substance moving along its Grady in is going to power the movement of another substance against its radiant. All right with that, let's flip the page.