In this video, we're going to introduce electron carriers, specifically NADH and FADH2. It's important to note that many biological processes that we will discuss, including cellular respiration, conduct redox reactions using electron carriers. These electron carriers are helpful to perform redox reactions. Electron carriers such as NADH and FADH2 each carry or transport a maximum of 2 electrons. NADH and FADH2 can shuttle electrons to different locations within a cell, much like an electron taxi cab. You can think of NADH and FADH2 as electron taxi cabs, and we'll be able to see that down below in our image.
It is also important to note that NAD+ and FAD are the oxidized forms of NADH and FADH2 respectively. Recall that in oxidation (represented by LEO), the species losing electrons is oxidizing. This means that NAD+ and FAD will have fewer electrons; they have lost electrons compared to NADH and FADH2. Let's take a look at our image down below to clarify some of this.
The electron carriers we are discussing, NADH and FADH2, act like electron taxicabs. In the image, you can see an electron taxicab. On the left-hand side, you notice the empty form of the electron taxicab. However, when this electron taxicab picks up its 2 passengers, these 2 electrons, it becomes a full taxicab. Over here, we have the 2 electrons inside this electron taxicab, illustrating what NADH and FADH2 act as these electron taxi cabs.
We observe that NADH forms when the oxidized form, NAD+ (the empty taxicab version), picks up its 2 passengers, these 2 electrons, along with a hydrogen ion, and it forms NADH. You can see that NADH is carrying these 2 electrons, the passengers of the taxicab, but it also picks up a hydrogen atom. When we look at FAD, this is the empty taxi cab version of the electron carrier. But when it picks up its 2 passengers, these 2 electrons, it also picks up 2 hydrogen ions and becomes FADH2, the full taxicab version of this electron carrier.
One way to help you remember that NADH and FADH2 are the full taxicab versions is just to think that they are a bit heavier because they're gaining electrons and hydrogen ions. Those labeled with 'H' are just a little bit heavier, and thus, they are the full taxicab versions. As we move forward in our course discussing cellular respiration, it's significant to note that during cellular respiration, these electrons carried by NADH and FADH2 are going to go to what's known as the electron transport chain, which is the final stage of cellular respiration. We'll discuss this more as we progress in our course. For now, notice the full electron taxicab here, where one of the electrons is asking, "Where are we going?", and the other electron responds, "To the electron transport chain, duh." This memorable interaction highlights what we will learn about how NADH and FADH2 take their electrons to the electron transport chain during cellular respiration.
This concludes our brief introduction to electron carriers, NADH and FADH2, and we'll be able to get some practice applying the concepts we've learned here as we move forward in our course. I'll see you all in our next video.