Name the electron carrier that transports electrons from complex I to complex III.

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Accepted Answer

Hi everybody. And let's look at our next question, which molecule is responsible for transferring electrons from complex two to complex three in the electron transport chain. A cytochrome CB ubiquinone C oxygen or DNA DH. So this one is a bit tricky as the electron transport chain can definitely get a bit convoluted and confusing at times. But if we can't remember off the top of our head, there's two, we can rule out right away. So we can recall that there are a total of four enzyme complexes. So four enzyme complexes total in the electron transport chain. So if we're looking at transferring electrons from complex 2 to 3, we know we're talking about sort of in the middle of the electron transport chain. So that lets us rule out both c oxygen because remember that oxygen is the final electron acceptor. So that's going to take electrons from complex four at the very end. And then choice DNA DH, because this is the electron carrier that delivers electrons to the beginning of the electron transport chain. So we can really draw out two of our choices. Now, we need to remember is it cytochrome C or ubiquinone. We also want to remember that ubiquinone is also known as co enzyme Q or CO Q because sometimes diagrams are labeled this way. So the easiest way to remember this is I like to keep in my head a very rough simplified diagram of the electron transport chain to keep things straight. So just have it in your head or do a quick sketch on your test, just whatever you need to kind of keep yourself oriented like a little road map there. And I have my own simplified diagram showing the four enzyme complexes that are embedded in the inner membrane of the mitochondria. And we see complex one is where N A DH delivers its electrons, all ao sync two electrons coming in there. And those electrons go through to coenzyme Q. But also recall that fa DH two is also an electron carrier that enters a little bit later in the electron transport chain since its electrons are at slightly lower energy and those electrons enter by way of complex two. So remember those two are side by side and then they both funnel electrons into coenzyme Q. So maybe a way to remember that is that it's a coenzyme think of it's taking electrons from two things. They are coexisting together. Just a silly way to remember that. And then the electrons funnel from coenzyme Q or ubiquinone on to complex three. So our molecule that is what does the transfer from 2 to 3 is choice B ubiquinone. So that does get a little bit confusing since you know, the electrons from N A DH bypass complex two. But again, if we kind of keep this sort of diagram straight in our heads, that can help us to remember where everything goes. And you can see that choice. A cytochrome C is further along that funnels electrons from complex three to complex four. So we'll write from 324. So that's why choice A is incorrect. So once again, the molecule that transfers electrons from complex two to complex three in electron transport chain is choice B ubiquinone. See you in the next video.

Name the electron carrier that transports electrons from complex I to complex III.

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Key Concepts

Electron Transport Chain

NADH and FADH2

Ubiquinone (Coenzyme Q)