- Krebs (citric acid) cycle and oxidative phosphorylation questions
- Oxidative phosphorylation questions
- The citric acid cycle
- Krebs / citric acid cycle
- Regulation of pyruvate dehydrogenase
- Regulation of Krebs-TCA cycle
- Electron transport chain
- Oxidative Phosphorylation: The major energy provider of the cell
- Oxidative phosphorylation and chemiosmosis
- Regulation of oxidative phosphorylation
- Mitochondria, apoptosis, and oxidative stress
- Calculating ATP produced in cellular respiration
Oxidative phosphorylation is a vital cellular respiration process that generates ATP. It involves the oxidation of NADH and FADH2 and phosphorylation. The process creates a hydrogen gradient, enabling chemiosmosis and ATP synthesis. This energy conversion is essential for all life forms, from bacteria to sharks. Created by Sal Khan.
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- Please enlighten me on NADH and FADH. I searched the 8 lectures for an explanation to no avail.(9 votes)
- Both are electron carriers, which just means they store electrons at a relatively high energy state. These electrons can be used to power other reactions, when they go to a lower energy state and release energy for use in the reaction.(4 votes)
- If phosphorylation can happen directly without oxidation (substrate phosphorylation) then why is there oxidative phosphorylation at all? Why not just use substrate phosphorylation all the time?(6 votes)
- Substrate phosphorylation is not used all the time because it cannot produce ATP from NADH and FADH2, whereas oxidative phosphorylation can. Because of this, more ATP can be produced from a single glucose molecule, making cellular respiration more efficient.(9 votes)
- I've been wondering about this for a while, because in the textbooks and these videos continuously NADH is "named" as the e- carrier, but the diagrams that will be used on our exam (it's officialized so we recognize them) keep saying NADH2 being passed around. So, I'm getting quite confused what the difference is, and why one say NADH while the other says NADH2. Does anyone know?(4 votes)
- There is NADH, and then there is FADH2. NADH is the "electron carrier" because it picks up electrons from things in glycolysis and the Krebs Cycle, and gives those electrons to the electron transport chain, so that they can be used to make Energy / ATP. If you see NADH2 written, you can just consider it to mean NADH (but if you know they want you to write NADH2 on the test I would still say go for that - just make sure to not confuse it for FADH2)
NADH2 is sometimes used because technically the reduction of NAD+ is [2H and NAD+] --> [NADH and H+] , but really, it is only the NADH of those products that is actually interacting with the electron transport chain.(5 votes)
- I can't understand what are electron carriers . Can you please tell me ?(3 votes)
- Any of various molecules that are capable of accepting one or two electrons from one molecule and donating them to another in the process of electron transport. As the electrons are transferred from one electron carrier to another, their energy level decreases, and energy is released. Cytochromes and quinones (such as coenzyme Q) are some examples of electron carriers.(7 votes)
- Can you make a video on substrate level phosphorylation ?(3 votes)
- whats the difference between oxidative phosphorylation and substrate phosphorylation? also regarding the electron transport chain, is cytochrome Q the only complex (out of the 4, not including ATP synthase) that doesn't pump hydrogen atoms to the inner membrane space? please get back to me i have an exam on tuesday!(3 votes)
- atp directly synthesised during substrate oxidation is called substrate level phosphorylation..whereas oxidative phosphorylation is linked with mitochondrial electron transport chain..(2 votes)
- What is a coupled reaction and why is oxidative phosphorylation considered a coupled reaction?(3 votes)
- A coupled reaction is one where the free energy of a thermodynamically favorable reaction (such as the hydrolysis of ATP) is used to drive a thermodynamically unfavorable reaction by coupling or 'mechanistically joining' the two reactions.
The most important coupled reaction occurs in oxidative phosphorylation that occur during respiration (i.e. that which occurs beween oxidation of fuels and synthesis of ATP by ATP synthetase).
In the chemiosmotic theory of oxidative phosphorylation, electron transport via the respiratory chain to molecular oxygen creates a proton gradient across the inner mitochondrial membrane (which is normally impermeable to protons). Protons are pumped outwards. This proton gradient, or protonmotive force, may be used to 'drive' the formation of ADP to ATP (thermodynamically unfavorable) reaction to the right, via the ATP synthetase complex.
Source: http://biology.stackexchange.com/questions/2051/what-is-a-coupled-reaction-and-why-do-cells-couple-reactions(2 votes)
- Can someone please explain Chemiosmosis? I don’t really understand how it works with the atp synthase? Thank you!(3 votes)
- Wouldn't the water equation be that O2+4e-+4H+-->2H2O ?(2 votes)
- Yes, but in this video he wanted to focus on the production of just one water molecule, that´s why he used 1/2 O2 intead of just using whole numbers. So you´re right, your equation is the balanced equation we would normally use.(2 votes)
I made a slight error in the electron transport chain video. And I just wanted to correct it in this one. And it's also an opportunity for me to include a little bit of terminology that I forgot to include in that video. So when I described the electron transport chain, you remember, it's just you have some high-energy electrons in NADH and they get transferred from one molecule to another. And as they get transferred they go into lower energy states and they release energy. And then the final electron acceptor was oxygen. Oxygen got reduced right here. But if you look at both sides of this equation, the mistake was, I need two hydrogens. If I have two hydrogens on the right-hand side of the water, I need two hydrogens on the left-hand side. So there should be a 2 right there. So that was what I would consider to be a minor mistake in the last video. But this also gives me a chance to introduce you to some more terminology. So this whole process, we know that this is called oxidation. When NADH loses a hydrogen. Remember oxidation is losing, formally electrons. But when it loses the hydrogen, it loses the opportunity to hog that hydrogen's electrons. So this whole process of the electron transport chain is one molecule after another getting oxidized until you have a final electron acceptor in water. So this is-- obviously you could call this oxidation. You know, just very generally. And then the second part of the electron transport chain-- or maybe we shouldn't even call this part of the electron transport chain-- the process where the ATP is actually formed. The adding of a phosphate group to another molecule is called phosphorylation. So the whole process of creating ATP through the electron transport chain. Remember the electron transport chain releases energy that creates this hydrogen gradient. It pumps the hydrogens to the outer compartment. And then that gradient, those hydrogens that want to get back into the matrix, essentially going back through this ATP synthase. This process of generating ATP this way is called oxidative phosphorylation. It's a good word to know. You might see it on some standardized tests or on your exams. And it's called this because you have an oxidative part. Each of these molecules gets oxidized in the electron transport chain as they lose their hydrogens or as they lose their electrons. That creates a hydrogen gradient. And then that, through chemiosmosis, allows for phosphorylation. So that's another good word to know. The transfer of these hydrogens, these kind of going through this membrane selectively. This membrane, this ATP synthase, wouldn't allow just any molecule to go through it. It's allowing these hydrogen protons to go through it. This process right here of this hydrogen going through is called chemiosmosis. Another good word to know. So the entire process is called oxidative phosphorylation. They don't happen at the same time. Oxidative generates the energy because the energy to push the hydrogens out. And then the phosphorylation happens as the hydrogens experience chemiosmosis and go back in and turn this little axle and then push the ADP and the phosphate groups together. And then you can contrast that with substrate. Substrate phosphorylations. Since I'm in the mood to introduce you to terminology. Substrate phosphorylation. This is actually what happens when the ATP is produced directly in glycolysis in the Krebs cycle. And this is where you have an enzyme directly helping to peruse the ATP without any type of chemiosmosis or proton gradient. So if you imagine an enzyme, some blurb, some big protein blurb. And let's say it has the ADP there with its two phosphate groups. And then maybe it has another phosphate group that attaches at some other part of the enzyme, this enzyme facilitates without any kind of chemiosmosis or oxidation. It facilitates, probably in conjunction with other energy releasing reactions that may be occurring on other parts of the enzyme. So maybe you can imagine a little spark right there and then that twists this entire enzyme. This isn't exactly how it might work, but it's a good idea. And then these two things maybe get pushed together. When it's just an enzyme without any of this chemiosmosis that's driven by oxidation, like we learned in the electron transport chain, we call this substrate phosphorylation. And the substrates are just the things that attach to the enzyme and have something performed on them. So anyway, hopefully you found this little video mildly useful.