Fermentation & Anaerobic Respiration - Video Tutorials & Practice Problems

What Happens to Aerobic Organisms if There's No Oxygen?

in this video, we're going to begin our lesson on fermentation and anaerobic respiration. And so up until this point, in our course, we've really been focusing on aerobic cellular respiration in the presence of oxygen. But here in this video, we're going to address Well, what happens if Arabic organisms don't have any oxygen around well without oxygen, Arabic cellular respiration? As we've discussed it in our previous lesson, videos cannot occur. So aerobic cellular respiration can Onley occur if oxygen is present. But without oxygen, as the final electron except, er, the electron transport chain is gonna get backed up like a traffic jam. And ultimately, the amount of n a d. H is going to increase, whereas the amount of n a. D plus is going to decrease significantly down to dangerously low levels. And so if we take a look at our image down below the top half of this image notice that we have, like Collis, is here as the very first step of cellular respiration. And once again, if oxygen is present, then cellular respiration would occur as we've discussed it in our previous lesson videos where Pirated oxidation would occur. Then the crab cycle, then the electron transport chain in Kenya's Moses. But once again, these stages here are on Lee going to occur if oxygen is present. If there's no oxygen present, then these stages are not going to occur. And instead, if there's no oxygen, then fermentation is going to take place. And so the process of fermentation is a process that's going to use the electrons from these any DHS that have increased to reduce Piru of it and generate alternative molecules that end up regenerating N a. D Plus is that, uh, the N A D plus is have gotten dangerously, dangerously low. They've decreased really, really low. So one of the big takeaways of fermentation is that it's going to help regenerate those n a d Plus is that have gotten dangerously low now, depending on the specific type of organism, the pyro of it that gets reduced can be reduced to either lactic acid or it could be reduced to alcohol. And so later in our course will discuss lactic acid fermentation and alcohol fermentation as well. Now fermentation ultimately is going to make very, very little amounts of a teepee, and so really Onley, some uni cellular organisms can survive on just fermentation alone. But multi cellular organisms they cannot survive on just fermentation because it makes so little a teepee that it's not enough to drive the energy processes that are needed by multi cellular organisms. But fermentation is advantageous because it will allow for the regeneration of N A D plus, as we've already indicated, and that regeneration of any D plus is really critical to allow, like Kalle assists, to continue even in the absence of oxygen. And so even when there is no oxygen, like Collis is, is able to continue and produce the small amount of 80 p that it does because fermentation regenerates the n a d plus that it needs. So in order to get a better understanding of this, let's take a look at this image that we have down below. And so recall that once again, the electron carriers and a. D. H and F D H two s, they can be represented as these electron taxicabs and so notice. Here we have these electron taxicabs and all of these other electron carriers here that we're showing as these other vehicles, and so notice that what we're showing you here in this image is that there is no oxygen acting as the final electronic sector. And so when you take a look at this sign here, notice that it says specifically that the electron transport chain is backed up because there's no final electron except eR or no oxygen gas, uh, toe act as the final electron accepted. And so when there is no oxygen, what happens is the amount of N a d H is are going to increase significantly. And so the electron transport chain is gonna get backed up like a traffic jam. And so notice here, what we have is a traffic jam because there's no final Elektronik sector and there's no oxidative phosphor relation, which means there's not a lot of 80 p being generated when there's no oxygen. However, even when there's no oxygen, fermentation can take place. And so notice Over here we have this fermentation plant that has a sign that says, Hey, we'll empty your taxi to help glide colle Asus and make a little bit of a teepee just from like Collis. And so this electron carrier here, this electron taxicab is basically saying, Let's take this exit so that we can help out, like Collis Iss and help Glen Collis make a little bit of a teepee. And so the fermentation plant is able to take the N a. D H is that are being built up, and it's basically able to take those electrons. And it's able to reduce Piru bit to generate either lactic acid in some organisms or ethanol or alcohol in some other organisms. And so this is Ah, fermentation is going to regenerate the N a D plus or the empty taxi cab, and the empty taxi cab or N a D plus is needed. In order to allow Glide, Collis is to continue forward. And so the empty taxicab is going to, um, allow for glide. Collis is to take place and, like dialysis, is going to be able to produce a little bit of a teepee even when there's no oxygen gas and the n a. D. H s are backed up in this traffic jam. And so notice that this here is a loop that can continuously happened so that glide Colle Assis is able to continuously run even in the absence of oxygen. But once again, like Kallis is only produces a small amount of 80 p just to a tee pee molecules. And so Glen Collis is the amount of 80 p that it produces is not enough to allow multi cellular organisms like ourselves to survive in the absence of oxygen. And so, uh, this here really just shows how fermentation is critical to allowing, like Collis is to continue in the absence of oxygen. And so we'll get to talk even mawr about fermentation moving forward in our course when we talk about lactic acid fermentation and alcohol fermentation. But for now, this here concludes our introduction to what happens to Arabic organisms if there's no oxygen and how fermentation is going to take place when there is no oxygen. And so we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video

Fermentation allows a cell to:

a) Recycle NADH to NAD⁺ for glycolysis.

b) Use NADH as a terminal electron acceptor.

c) Reduce NAD⁺ to NADH for glycolysis.

d) Synthesize ATP via ATP synthase.

• A. Recycle NADH to NAD⁺ for glycolysis.
• B. Use NADH as a terminal electron acceptor.
• C. Reduce NAD⁺ to NADH for glycolysis.
• D. Synthesize ATP via ATP synthase.

Lactic Acid Fermentation

in this video, we're going to briefly introduce lactic acid fermentation. And so lactic acid fermentation is really just when Piro of it is reduced by any th toe form lactic acid or lack tape along with N a D Plus that's ultimately gonna help drive like Collis ISS. And so down below, over here in our image notice we're showing you lactic acid fermentation and so notice that when there's absolutely no oxygen, the normal processes that we've talked about for aerobic cellular respiration such as Pirated oxidation, the Krebs Cycle and the electron transport chain in Kenya, as Moses cannot occur, however, glide colle assists eyes going to be able to occur. And the reason for that is because lactic acid fermentation represented by this red arrow right here, is going to ultimately generate lactic acid or lack tape. And the Piru bit here is going to get reduced instead of being oxidized like it was normally was step two of aerobic cellular respiration. So the pirou is going to get reduced because it's going to be gaining electrons, and ultimately it's gonna be converted toe lactic acid and through this lactic acid fermentation here, the big part is that it regenerates the n a D plus here, the empty electron taxicab and this empty electron taxicab, the N a D plus is needed. In order for glide, Collis is to continue forward. And so, ultimately, lactic acid fermentation is allowing for glide. Collis is to proceed. Ford, even in the absence of oxygen and like colossus, is able to produce a small amount of 80 p just to a tee pee molecules and a little bit is certainly better than No. 80 p molecules. And so lactic acid fermentation will allow for such a small amount of eight p to be made vehicle like Hollis. Okay, and so lactic acid fermentation eyes actually going to occur in human muscle cells. But also it can occur in bacteria as well. And when it does occur in bacteria, this is what gives yogurt. It's sour taste, and so notice down below. Over here, on the right hand side of the image. We're showing you a human muscle here to remind you that lactic acid fermentation will actually occur in our muscle cells when we're doing X tremulous exercise, and our muscles are low on oxygen. Uh, lactic acid fermentation will occur, and our muscles are able to still produce a little bit of energy via a T P. But that small amount of a TPV produced vehicle callouses is not going to be enough to sustain our muscle cells, and so it can Onley occur for a small amount of time. And then we'll have to stop performing the exercise so that we can get more oxygen and allow our normal aerobic cellular respiration take place. But also lactic acid fermentation can also occur in bacteria that are found in yogurt and that gives yogurt. Once again. It's sour taste. And so this year concludes our brief introduction to lactic acid fermentation and our next video, we'll get to talk about alcohol fermentation, so I'll see you all there.

Alcohol Fermentation

in this video, we're going to briefly introduce alcohol, fermentation, and so alcohol. Fermentation is really similar to lactic acid fermentation, and really, the difference is that the Piru bait and alcohol fermentation is going to be reduced by an a D H toe form ethanol instead of forming lactic acid. And ethanol is really a type of alcohol now. Also, alcohol fermentation is not only going to produce ethanol, but it's also going to regenerate the n A D plus. Allowing for like Collis is to continue even in the absence of oxygen. And so taking a look at our image down below notice that we're showing you alcohol fermentation and notice that alcohol fermentation is basically going to be very, very similar to lactic acid fermentation. The only difference is that ethanol is going to be produced instead of lactic acid. And also, once again, the N a D plus is air going to get regenerated through, uh, alcohol fermentation. And when N a D plus gets regenerated that can be utilized to help continuously. Dr Glide Collis is even in the absence of oxygen and, like palaces can continue to produce. It's very small amount of 80 p. And so alcohol fermentation is really going to produce beer from barley, the beer that humans can drink and also wine from grapes as well. And so over here on the right hand side noticed that we're just showing you an image of a brewery and ice cold beer just to remind you that alcohol fermentation is what can drive and produce the alcohol's that we drink. And so this year concludes our introduction to alcohol fermentation, and we'll be able to get to practice as we move forward in our course, so I'll see you all in our next video.

Which of the following describes a primary function of both lactic acid fermentation and alcohol fermentation?

a) Reduction of NAD⁺ to NADH.

b) Oxidation of NADH to NAD⁺.

c) Reduction of FAD to FADH₂.

d)  Hydrolysis of ATP to ADP.

• A. Reduction of NAD⁺ to NADH.
• B. Oxidation of NADH to NAD⁺.
• C. Reduction of FAD to FADH₂.
• D. Hydrolysis of ATP to ADP.

Anaerobic Respiration

in this video, we're going to introduce anaerobic respiration and so recall from our previous lesson videos when we introduced fermentation that fermentation can Onley produce a very small amount of 80 p by allowing like Collis is to continue. And again, Glen Collis is only produces a little bit of a teepee and so not a lot of 80 p has made during fermentation. However, some uni cellular organisms can actually survive and make a significant amount of eight eep even without oxygen. And so this is exactly where anaerobic respiration comes into play. And so the term anaerobic is a term that means without oxygen or in the absence of oxygen. And so anaerobic respiration is going to use some other molecule other than oxygen gas as the final electronic sector of the electron transport chain. And so anaerobic respiration is practically going to be the same as aerobic respiration, except for the fact that the final electron, except er, is not going to be oxygen. An anaerobic respiration, the final electron accepted is gonna be some other molecule instead of oxygen. And so some of the alternative electron except er's, include nitrate or No. Three minus sulfate or s 04 to minus, and even carbon dioxide can act as the final electron except, er an anaerobic respiration. And so, really, the biggest difference between anaerobic respiration and fermentation is that anaerobic respiration is going to make ah lot mawr a teepee than fermentation. Even though they both occur without oxygen, Anaerobic respiration will make mawr 80 p than fermentation, which Onley makes a little bit of a teepee. But anaerobic respiration is actually going to end up making a lot less a teepee than aerobic cellular respiration. And so aerobic cellular respiration, which uses oxygen, is gonna make the most amount of 80 p, followed by anaerobic respiration, and then the least amount of 80 p is gonna be made by fermentation. And so if we take a look at our image down below right here, notice that it's the same image of the electron transport change from our previous lesson videos. But really, the Onley difference here is that there is some alternative final electron except er and notice that the final electron, except er is not oxygen. Instead, during anaerobic respiration, there's gonna be some alternative final electronic sectors such as either the night trade or the sulfate. And so instead of the electrons making their way to the final destination of Orlando or oxygen, the final destination is gonna be some other destinations, such as maybe New Orleans to represent the end in the nitrate or San Antonio to represent the S and the sulfate. And so these alternative final electronic sectors are going to be present in anaerobic respiration. And so this year concludes our introduction to anaerobic respiration, and we'll be able to get some practice as we move forward in our course. So I'll see you all in our next video.

In which of the steps of aerobic and anaerobic cellular respiration does substrate-level phosphorylation occur?

a) In glycolysis only.

b) In the Krebs cycle only.

c) In the electron transport chain only.

d) In both glycolysis and the Krebs cycle.

e) In both the Krebs cycle and the electron transport chain.

• A. In glycolysis only.
• B. In the Krebs cycle only.
• C. In the electron transport chain only.
• D. In both glycolysis and the Krebs cycle.
• E. In both the Krebs cycle and the electron transport chain.

Which of the following statements about NAD⁺ is true?

a) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the Krebs cycle.

b) NAD⁺ has more chemical energy than NADH.

c) NAD⁺ donates high energy electrons to the electron transport chain.

d) In the absence of NAD⁺, glycolysis can still function.

• A. NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the Krebs cycle.
• B. NAD⁺ has more chemical energy than NADH.
• C. NAD⁺ donates high energy electrons to the electron transport chain.
• D. In the absence of NAD+, glycolysis can still function.