In this video, we're going to introduce anaerobic respiration. Recall from our previous lesson videos when we introduced fermentation, that fermentation can only produce a very small amount of ATP by allowing glycolysis to continue. Again, glycolysis only produces a little bit of ATP, and so not a lot of ATP is made during fermentation. However, some unicellular organisms can actually survive and make a significant amount of ATP even without oxygen. This is exactly where anaerobic respiration comes into play. The term 'anaerobic' means without oxygen or in the absence of oxygen. Anaerobic respiration is going to use some other molecule other than oxygen gas as the final electron acceptor of the electron transport chain. Anaerobic respiration is practically going to be the same as aerobic respiration except for the fact that the final electron acceptor is not oxygen. Some alternative electron acceptors include nitrate or NO3-, sulfate or SO42-, and even carbon dioxide can act as the final electron acceptor in anaerobic respiration.
The biggest difference between anaerobic respiration and fermentation is that anaerobic respiration is going to make a lot more ATP than fermentation. Even though they both occur without oxygen, anaerobic respiration will make more ATP than fermentation, which only makes a little bit of ATP. But anaerobic respiration is actually going to end up making a lot less ATP than aerobic cellular respiration. Aerobic cellular respiration, which uses oxygen, is going to make the most amount of ATP followed by anaerobic respiration, and then the least amount of ATP is going to be made by fermentation. If we take a look at our image down below here, notice that it's the same image of the electron transport chain from our previous lesson videos, but really, the only difference here is that there is some alternative final electron acceptor. The final electron acceptor is not oxygen. Instead, during anaerobic respiration, there's going to be some alternative final electron acceptor such as either the nitrate or the sulfate.
This concludes our introduction to anaerobic respiration, and we'll be able to get some practice as we move forward in our course. I'll see you all in our next video.
