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Cell Biology

Learn the toughest concepts covered in Cell Biology with step-by-step video tutorials and practice problems by world-class tutors

10. Anerobic Respiration



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Hello everyone in this lesson. We are going to be learning about anaerobic respiration and fermentation. So let's talk about what fermentation actually is fermentation is going to be one of the major steps in anaerobic respiration or respiration without oxygen. So fermentation is going to be the process that breaks down sugar to produce A. T. P. In the absence of oxygen. That is the key point. Their oxygen is not present for fermentation. That's why it's anaerobic respiration. Now whenever we're talking about fermentation we're going to have two main steps. We're going to have glycol icis and then fermentation and we're going to talk about the two different types of fermentation. So it's important to remember that glycol icis does not require oxygen. The later stages of aerobic cellular respiration like the citric acid cycle and the electron transport chain do require oxygen. But like Alexis does not. So glycol ISIS is going to happen in anaerobic organisms but fermentation is needed for other steps. So glycol icis needs a supply, a constant supply. This is a typo supply of in A. D. Plus which is an electron carrier that is able to accept that electron that is created or released via glycol assist. So this is an electron carrier. Now glide colossus cannot create its own in A. D. Plus. It only makes in A. D. H. Which is the form that is already carrying the electron. Now in aerobic cellular respiration. You're going to see that in A. D. Plus is going to be remade in the process of the citric acid cycle and the electron transport chain and then it's given back to like Alexis. Now, what is going to be important here is that fermentation is going to be utilized to recreate the A. D. Plus. That is needed. So that guy collis can continue. So without oxygen in A. D. H. Cannot be oxidized to in A. D. Plus. So it cannot be reused. So glycol icis cannot continue. So like Alexis cannot continue. This is where the process of fermentation is going to step in fermentation regenerates in A. D. Plus. So it can be reused in glycol icis. So these organisms, even without the presence of oxygen are able to continually make A T. P. Okay, so electrons are transferred from the N. A. D. H. Created in black colossus to the piru molecules that are also created in glycol icis to generate the N A. D plus. And this is going to be the main process of fermentation. So this is going to be an example of that happening in this diagram right here. So this example here is going to be a diagram that is representing an aerobic respiration. And as you guys can see anaerobic respiration doesn't have that many steps as compared to aerobic respiration. There's actually going to be those two main steps like Alexis and fermentation. Okay, so we know that it's going to start up here because we have glucose and glucose is taken in as a nutrient and it is going to be broken down and in fact this particular stage in the process of anaerobic respiration is going to be good michael icis right here because we are breaking down glucose and as you guys can see to A T. P. Have been created in A. D. H. Has been created and to piru bite molecules have also been created. Now the next step in this process is going to be fermentation but a particular type of fermentation, this is going to be alcohol fermentation and I knew that because you guys can see that to ethanol molecules were created now there's also another type of fermentation which are important to know and that's going to be lactic acid fermentation. So this is alcohol fermentation and are to piru molecules are going to lose two molecules of C. 02 and they're going to turn into a set alga hide. Sorry, that's hard to say for me a settle al to hide. And then this is going to go through the process of fermentation. So in A. D. H. Is going to be turned into in A. D. Plus and this is going to create the to ethanol molecules and then that any D plus can go back to glucose and be used again. This is alcohol fermentation. It's important to know that there is also lactic acid fermentation. So what's going to happen is you're going to have these two piru molecules that are made via glycol Asus. The process of glycol Asus is exactly the same. You're going to have glucose, you're going to create to A T. P. You're going to create an A. D. H. And to PIRU molecules. And then if you go down the path of lactic acid fermentation, something else is going to happen. So we're going to have these two PirU molecules and we're going to create two lactate molecules or lactic acid. Okay, so these two PirU molecules turn into lactic acid and from this process you are going to turn in A. D. H. Into in A D plus and then that in A D plus can go on to be utilized in glycol assist again. So this one right here that I drew for you guys is lactic acid fermentation. It's just two different ways to do the same thing. Alcohol fermentation is commonly going to be utilized by things like yeast yeast cells. This is how we're going to get many of the alcohols that we drink. And lactic acid fermentation is going to be used by your muscles whenever they run out of oxygen because you're working out so hard lactic acid fermentation is what our muscles are going to use. Okay, so now let's go down and talk about the rest of this information. Okay, so what's going to happen is this is going to be the rest of the information, which I already talked to you guys about up there, You're going to use the piru bait as an electron except er And then this is going to actually begin to limit the other metabolic pathways that you have. You guys can see up here that this Piru bait that was created was used as an electron except er It took the electrons from in A. D. H. And generated in A. D. Plus. And once it takes those electrons it's going to turn into a different molecule either ethanol or lactic acid and once it turns into those other molecules it's going to limit the use of other metabolic pathways ethanol and a lactic acid are difficult for organisms to use. So in the presence of oxygen, it generally goes through other metabolic pathways. Whenever glycol ISIS creates piru bait, it then will travel into the citric acid cycle and then those products will travel to the electron transport chain and the average amount of energy that is made in aerobic cellular respiration is vastly higher than that which is created in anaerobic respiration. So without oxygen, many by products are made and those by products are things like ethanol and lactic acid and they do not go on to create a. T. P. So you lose a lot of that potential energy because lactic acid and ethanol are not utilized by the rest of the system. So The next sentence here says Piru v. eight conversion results in numerous by products. And the problem with these by products is we don't utilize these by products to make more energy. There simply waste products. So again you can have lactate fermentation which produces lactate or lactic acid and this is commonly found in things like cheese and milk. But your muscles use this process as well whenever they run out of oxygen and they turn to anaerobic respiration, they're going to use lactic acid fermentation or lacto fermentation and then alcohol fermentation is the one in the example above and this is going to produce ethanol and co two yeast do this. They make ethanol, they also make C. 02 gas which is going to make things like bread rise for baking and the ethanol is going to be used for brewing and the creation of beer. So we have harnessed these methods these biological pathways for our own good but we utilize these biological pathways as well. We commonly do aerobic respiration simply because it makes vastly more A. T. P. I believe it makes around 32 to 34 80 p. Well the process of like Alexis and fermentation in anaerobic respiration make about 4 80 P. I think. So it's really inefficient. It's really not good and it has all of these byproducts and lactic acid when it pulls up in your muscle cells can actually make you sore. So it's not a good product for us to make, we want to have that oxygen. So we can get the most energy out of it. But organisms that do not possess oxygen or live in environments without oxygen are going to use anaerobic respiration, and that includes glycol, icis and fermentation. Okay, everyone, let's go on to our next lesson.

Which of the following is not associated with fermentation?


The purpose of fermentation is to produce what?


True or False:The creation of pyruvate in the absence of oxygen is more energetically favorable than the creation of pyruvate in the presence of oxygen.