ATP Synthesis Driven from Proton Gradients - Video Tutorials & Practice Problems

ATP Synthesis

in this video, we're gonna be talking about 80 p synthesis driven from proton gradients. So first I just want to say that this might be a little bit of a long video. Um I just wanted to make sure that everything was all together so that it made sense. Um So it will be a little longer. But essentially it all is connected. So we're all talking a T. P synthesis and how that happens driven from proton gradients. So the first thing is that an electrochemical proton gradient, which remember electrochemical what that means, Right? So that's gonna be an electrical gradient and a chemical gradient. And that is going to drive a T. P synthesis. So how this electrochemical proton gradient is created is created by the electron transport chain which creates this high concentration of hydrogen protons across the membrane. And it also creates a charge gradient which you might see a voltage gradient. Which of course if there's a lot of protons that's gonna be a lot of positive charge across the membrane. Um So that is how that ends up being an electrical member electrochemical gradient. So like I said, this is driven by the electron transport chain, which means that it's going to be a cross which mitochondrial membrane, right? The inner mitochondrial membrane. And then this gradient undergoes kimmy osmotic coupling, meaning that the hydrogen pumping due to the electron transport chain um drives this other chemical process known as a T. P synthesis. So you don't need to see really understand any of what's going on here. But what you can see is that the electron transport chain results in this huge amount of hydrogen protons across the membrane. So this is the inner membrane here. So that's an electrochemical proton gradient and then that's coupled. So there's some type of coupling here which couples this gradient with the production of a TB. So that's what I'm talking about when I'm talking about this electrochemical proton gradient and then kimmy is not a coupling. There's a lot of fancy terms just meaning that this proton gradient is created and that is used to drive the synthesis. So the protein that's responsible for creating a teepee or creating A T. P. Is called A T. P synthesis. And it's going to be a trans membrane protein that drives A T. P. Synthesis. So, um the one that we're going to focus on now is the one important in cell respiration, which is what we've been talking about in this chapter. And that's called the F one F 0 80 P synthesis. And so it uses this energy from the electrochemical proton gradient, which is what I've been beating over the Bush a lot of different times. So the F0 part is going to be the stationary head. So this catalyze is the A. T. P synthesis and its sound on the side of solid side of the membrane. Then you have the f. one which is going to actually not be stationary, it can rotate its gamma sub unit and that moves protons across the membrane. So the F zero is responsible for the A. T. P synthesis and the F. One transports protein. So this is how they're coupled. The two processes are coupled through these two different parts of A. T. P synthesis. Now the important part about this protein, it actually can run in reverse, meaning that it can use energy from a TP to pump protons if it needs to. For some reason I wouldn't necessarily say this happens a lot. But if the cell needs this super big proton gradient for something it can run in reverse. So 80 P synthesis though is mostly used to create a teepee. So let's look at what this looks like. So we have our inner mitochondrial membrane um we have our F. Zero and R. F. One part. So this is gonna remember me the stationary head which um and then we have our rotational sub unit. Sorry about that. So the hydrogen is actually going to flow through and this is going to rotate through this gamma sub unit and create a T. P. From a D. P. That's kind of how this A. T. P synthesis works. And like I said before proton pumping and 80 P synthesis are coupled events. So let's talk about each step of the proton pumping and the A. T. P synthesis. So first proton pumping happens. So the H plus for the proton moves through the F zero sub unit. And that results in a confirmation of change this confirmation, I'll change displaces protons further up the channel and eventually these protons are changing place just moving through the channel which results in rotation of the F. One channel. So this proton moving which is sort of spiraling up the channel actually will mechanically turn this F. One part and this rotation continually just like supports itself. Right? So as the hydrogen czar, you know, they bind in this channel and they displaced the other ones that are kind of spinning around this channel as that movement starts going it just continue and then it gets faster and better so then that you know that a tv sentences really going. It really ends up moving and when it does it moves faster and moves those protons down their gradient. Now with this movement 80 P synthesis couple a synthesis is couple. So this happens in three main stages. Because the energy from moving those protons across the membrane allows for the increase in affinity of ADP. So you have these three stages first you have the open stage where the F zero is going to bind the A. T. P. Very poorly and A D. P. Very weakly. Then you have a loose stage. So as the protons are you know starting to get going, starting to move this proton are starting to move this protein around it sort of switches stages and it comes loose so the fC are ahead is not going to bind a TP but it will bind ADP and phosphate. So now it's like okay, have these things I can say you can almost make it and then you have the tight stage. And so this is when it's going real fast, it's really spinning and these ADP and um prostate become so close together, they're bound tightly. Um they actually just form a teepee. And so the energy from too. So it takes about two hydrogen trans locations. So two proton movements to result in the confirmation of changes needed for a tv synthesis. And so 100 molecules of a T. P. Can be made per second. So that's about three A GPS for revolution. You don't need to know those numbers but just know that, you know this coupling happens where these are spinning around and um that's spinning results in conformational changes which then allow for a. T. P. To come in. So this is a really bad drawing I did. But just to give you an example what this is. So we have this http sent face and this is if you're kind of just looking down on it. So if this was if we just like cut it in half and then like looked at it kind of like tree rings, you can imagine like when you see tree rings, that's what we're looking at. So it has these three stages, the open stage where you know, nothing's really no hydrogen are being transferred and so it's just sort of stationary, but then it starts moving a little bit and you get to the loose stage and the ADP and phosphate can come in and then it really starts spinning and you get this tight phase where these come so close together, they just spontaneously form a teepee which then goes out and it can continue along this process as more hydrogen are being pumped across the membrane. So like I said, sorry, disappearing strobe lighting. So like I said, this is kind of a long video, but it's just to show, you know, this hydrogen pumping is very well conserved and also coupled with the synthesis of ITV so that let's now move on.

Which of the following is not a stage of ATP synthesis?

• A. A stage
• B. O stage
• C. T stage
• D. L stage

Which one of the following structures is responsible for catalyzing the ADP to ATP reaction?

• A. F₁ rotation
• B. F₀ head
• C. γ subunit

True or False:When ATPase is run 'backwards' its purpose is to convert ATP to ADP to create a H+ gradient.

• A. True
• B. False