In this video, we're going to introduce our map of the lesson on cellular respiration, which is this image that you see down below. And so this image is a map or an outline of our lesson moving forward. And so you can refer to this image as we move forward in our course and continue to talk more about cellular respiration. Notice towards the top of our map here, we have cellular respiration. And moving forward in our course, we're mainly going to be talking about cellular respiration in the presence of oxygen or where oxygen is available. In other words, we're going to talk mostly about aerobic respiration, which is cellular respiration in the presence of oxygen with oxygen present. Now later in our course we will talk a little bit about cellular respiration in the absence of oxygen without oxygen. And we'll mainly talk about anaerobic respiration as well as fermentation. Now, when oxygen is present, oxygen is going to serve as what is known as the final electron acceptor and we'll get to talk more about that as we move forward in our course.

Recall that one of the main purposes of cellular respiration is to generate energy in the form phosphorylation, or it could be generated via oxidative phosphorylation. We'll discuss the differences between substrate level phosphorylation and oxidative phosphorylation as we move forward in our course. Notice that the first and the third stages of cellular respiration are going to generate ATP via substrate level phosphorylation. The second stage, which is pyruvate oxidation, it turns out that it does not generate ATP directly. And then notice that the fourth stage of aerobic cellular respiration is going to generate ATP via oxidative phosphorylation. We'll talk more about these ideas as we move forward in our course.

What you'll notice is that, these stages that are labeled 1, 2, 3, and 4 are the main stages of aerobic cellular respiration. And so most of our attention is going to be focused on this region here of our map as we move forward in our course. But then we will also get to talk a little bit about some alternatives to the first stage of aerobic cellular respiration, some alternatives to glycolysis. That is going to be what is known as the PPP or the pentose phosphate pathway. We'll talk more about that. And then we'll also talk about the Etner-Doudoroff pathway or EDP here for short. Both of these alternative pathways to glycolysis are going to generate what is known as NADPH, but then they also are going to generate intermediates that will feed back into glycolysis, which is why we have arrows going from these alternative pathways back, leading back to glycolysis. We'll get to talk a lot more about these ideas as we move forward in our course.

Once we finish talking about aerobic cellular respiration on this left side over here, then we'll move on to talking about cellular respiration without oxygen. Once again, mainly talking about anaerobic respiration and fermentation. These are going to use alternative final electron acceptors that are not oxygen such as this nitrogen component here or this sulfur component over here. And then we'll also talk about different types of fermentation including lactic acid fermentation and alcohol fermentation. We're mainly going to be covering our lesson by following the leftmost branches first, and then we'll zoom out and talk about the right branches.

This here concludes our brief introduction to our map of the lesson on cellular respiration. Once again, feel free to use this map as a guide so that you can basically make predictions about what we're going to cover next and also to make sure that you are not lost within our lesson. I'll see you all in our next video.