Anaerobic Respiration

Summary

In this video, Mr. Andersen explains anaerobic cellular respiration, a process that occurs without oxygen or mitochondria. He contrasts it with aerobic respiration, detailing glycolysis, the Krebs Cycle, and the Electron Transport Chain. Anaerobic respiration involves glycolysis followed by fermentation, either lactic acid or alcoholic, allowing for ATP production despite oxygen deprivation. Examples include muscle exertion and yogurt production, illustrating the process's importance in energy generation under anaerobic conditions.

Takeaways

• 🌀 Anaerobic cellular respiration occurs without oxygen or mitochondria.
• 🔬 It consists of glycolysis followed by fermentation, unlike aerobic respiration which includes the Krebs Cycle and Electron Transport Chain.
• 🏃‍♂️ During anaerobic respiration, glycolysis produces 2 ATP but without the high ATP yield from the later aerobic stages.
• 🚫 The absence of oxygen or damage to mitochondria can halt aerobic respiration, emphasizing the importance of anaerobic processes.
• 🏋️ Lactic acid fermentation in muscles during intense exercise like sprinting can cause pain due to lactic acid buildup.
• 🍶 Alcoholic fermentation in yeast converts glucose into ethanol and carbon dioxide, used in brewing beer and making wine.
• 🔄 The conversion of NADH back to NAD+ in fermentation allows continuous glycolysis, sustaining ATP production.
• 🏅 Lactic acid fermentation is crucial for short bursts of high-intensity activity, providing a 'turbo boost' of energy.
• 🧬 Evolution has provided organisms with fermentation as a survival mechanism in oxygen-deprived environments.
• 📉 Over time, the accumulation of lactate or ethanol can be toxic to cells, ending the fermentation process.

Q & A

What is anaerobic cellular respiration?

Anaerobic cellular respiration is a process that occurs in the absence of oxygen or mitochondria, involving glycolysis followed by fermentation.

What are the three main stages of aerobic cellular respiration mentioned in the script?

The three main stages of aerobic cellular respiration mentioned are glycolysis, the Krebs Cycle, and the Electron Transport Chain.

How much ATP is produced during glycolysis in cellular respiration?

During glycolysis, 2 ATP molecules are produced, but since 2 ATP are also consumed in the process, the net gain is 2 ATP.

What happens to the pyruvate produced in glycolysis under aerobic conditions?

Under aerobic conditions, pyruvate enters the mitochondria, is converted to acetyl CoA, and proceeds through the Krebs Cycle and Electron Transport Chain to produce more ATP.

How does the lack of oxygen affect cellular respiration?

The lack of oxygen prevents the Electron Transport Chain from functioning, as oxygen is the final electron acceptor. This can lead to a buildup of NADH and a halt in glycolysis.

What are the two types of fermentation discussed in the script?

The two types of fermentation discussed are lactic acid fermentation and alcoholic fermentation.

What is the purpose of fermentation in the context of cellular respiration?

Fermentation allows cells to continue glycolysis and produce ATP when oxygen is scarce or absent by regenerating NAD+ from NADH.

How does lactic acid fermentation help in the absence of oxygen?

Lactic acid fermentation converts pyruvate into lactate, allowing the reuse of NAD+ and the continuation of glycolysis to produce ATP.

What is the role of lactic acid fermentation in muscle cells during intense exercise?

During intense exercise, muscle cells may undergo lactic acid fermentation to produce ATP quickly when oxygen supply is insufficient, leading to a buildup of lactic acid which causes muscle fatigue.

How does alcoholic fermentation differ from lactic acid fermentation?

In alcoholic fermentation, pyruvate is converted into ethyl alcohol and carbon dioxide instead of lactate, which is used by yeast in the absence of oxygen to produce alcohol for beverages like beer and wine.

What is the significance of the lactate threshold mentioned in the script?

The lactate threshold is the point during exercise where lactic acid starts to accumulate in the muscles, indicating the shift from aerobic to anaerobic metabolism and often the onset of muscle fatigue.

Outlines

00:00

🔬 Cellular Respiration Without Oxygen

Mr. Andersen introduces the concept of anaerobic cellular respiration, contrasting it with aerobic respiration. He explains that without oxygen or mitochondria, cellular respiration relies on glycolysis followed by fermentation. The video emphasizes the importance of understanding aerobic respiration first, which involves processes like glycolysis, the Kreb Cycle, and the Electron Transport Chain. Anaerobic respiration is highlighted as a fallback mechanism when oxygen is scarce, involving glycolysis and then either lactic acid or alcoholic fermentation. The summary also touches on the energy yield from these processes, with a focus on the limitations of anaerobic respiration and its role in scenarios like muscle exertion or food production.

05:04

🏃‍♂️ Lactic Acid Fermentation and Athletic Performance

This section delves into the specifics of lactic acid fermentation, explaining how it allows for continued glycolysis in the absence of oxygen, which is crucial during intense physical activity like sprinting. The discomfort felt during such activities is attributed to the buildup of lactic acid in muscles. The summary also mentions the role of lactic acid fermentation in food production, such as the creation of yogurt through the action of lactobacillus bacteria. The paragraph concludes with a discussion on alcoholic fermentation, particularly in yeast, which converts glucose into pyruvate and then into ethyl alcohol and carbon dioxide, a process essential for the production of alcoholic beverages. The historical context of fermentation is briefly mentioned, highlighting its long-standing significance in human culture.

Keywords

💡Anaerobic Cellular Respiration

Anaerobic cellular respiration refers to the process of energy production within cells without the presence of oxygen. In the video, this concept is crucial as it explains how cells can continue to produce energy (ATP) even when oxygen is scarce. This process is highlighted as an alternative to aerobic respiration, which requires oxygen. Anaerobic respiration includes glycolysis followed by fermentation, allowing cells to survive in low-oxygen conditions.

💡Aerobic Respiration

Aerobic respiration is the process by which cells generate energy (ATP) in the presence of oxygen. It is a more efficient way of producing energy compared to anaerobic respiration. The video uses aerobic respiration as a contrasting concept to explain the necessity of oxygen and the role of mitochondria in cellular energy production.

💡Glycolysis

Glycolysis is the initial step in both aerobic and anaerobic respiration, where glucose is broken down into pyruvate, yielding a net gain of 2 ATP molecules. The video emphasizes glycolysis as the common starting point for both types of respiration and as the process that can continue in the absence of oxygen, leading to either lactic acid or alcoholic fermentation.

💡Mitochondria

Mitochondria are the organelles within cells that are responsible for energy production, particularly during aerobic respiration. The video mentions mitochondria as the site where the Krebs Cycle and Electron Transport Chain occur, which are essential for efficient ATP production. The absence of mitochondria would necessitate anaerobic respiration.

💡Fermentation

Fermentation is the process that occurs after glycolysis in anaerobic respiration, where pyruvate is converted into either lactic acid or ethanol to regenerate NAD+, allowing glycolysis to continue. The video explains fermentation as a survival mechanism for cells when oxygen is not available, with examples including lactic acid fermentation in muscle cells and alcoholic fermentation in yeast.

💡Lactic Acid Fermentation

Lactic acid fermentation is a type of anaerobic respiration that occurs in muscle cells and certain bacteria, where pyruvate is converted into lactic acid. The video uses this concept to explain the build-up of lactic acid in muscles during intense exercise, which can cause muscle pain and the need to slow down or stop the activity.

💡Alcoholic Fermentation

Alcoholic fermentation is the process by which yeast converts pyruvate into ethanol and carbon dioxide in the absence of oxygen. The video mentions this process in the context of beer and wine production, where yeast fermentation plays a crucial role in creating alcoholic beverages.

💡ATP

ATP, or adenosine triphosphate, is the primary energy currency of cells. The video discusses ATP production throughout cellular respiration, emphasizing the varying efficiency of ATP generation in aerobic versus anaerobic conditions. ATP is central to understanding energy production in cells.

💡NADH and FADH2

NADH and FADH2 are electron carriers that play a critical role in the electron transport chain during aerobic respiration. The video explains that in the absence of oxygen, these carriers cannot transfer their electrons to oxygen, leading to a buildup of NADH and the necessity for fermentation to regenerate NAD+.

💡Kreb Cycle

The Krebs Cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria and are part of aerobic respiration. The video mentions the Krebs Cycle as the process following glycolysis, where pyruvate is further broken down to produce ATP, carbon dioxide, and more electron carriers.

💡Electron Transport Chain

The Electron Transport Chain is a series of protein complexes in the inner mitochondrial membrane that use the flow of electrons to pump protons across the membrane, creating a proton gradient used to produce ATP. The video explains that without oxygen, the electron transport chain cannot function, halting the production of ATP through aerobic respiration.

Highlights

Introduction to anaerobic cellular respiration as respiration without oxygen.

Necessity to understand aerobic respiration to grasp anaerobic respiration.

Anaerobic respiration involves glycolysis and fermentation.

Glycolysis breaks down glucose into pyruvate, yielding 2 ATP.

In aerobic conditions, pyruvate enters the mitochondria and Kreb Cycle.

Energy from Kreb Cycle is stored in NADH and FADH2.

Electron Transport Chain and oxygen's role in ATP production.

Potential disruptions to cellular respiration due to lack of glucose, mitochondria, or oxygen.

Anaerobic respiration as a solution when oxygen or mitochondria are absent.

Feeling the effects of anaerobic respiration by holding one's breath.

Glycolysis's role in producing energy and NADH.

Stagnation in glycolysis due to lack of NAD+ when all NADH is reduced.

Evolutionary solutions: lactic acid fermentation and alcoholic fermentation.

Lactic acid fermentation in animals and bacteria post-glycolysis.

Conversion of pyruvate to lactate in lactic acid fermentation.

Alcoholic fermentation in yeast converting pyruvate to ethyl alcohol.

Build-up of carbon dioxide as a byproduct of alcoholic fermentation.

Historical use of fermentation by Egyptians to make beer.

Anaerobic respiration's temporary nature before it becomes unsustainable.

Transcripts

Hi. It's Mr. Andersen and in this video I'm going to talk about anaerobic

cellular respiration. Or cellular respiration without oxygen. To understand anaerobic you

must first understand aerobic respiration. And so if these terms don't make sense to

you, glycolysis, Kreb Cycle and Electron Transport Chain, and if you don't even know what a mitochondria

is, you may want to go watch one of my videos on that. And I'll put a video link right up

here. But what is anaerobic cellular respiration? That's when we don't have oxygen. Or we don't

have a mitochondria present. And so let's get rid of those. And so what is anaerobic

respiration? It's really just glycolysis and then a new process called fermentation. And

so let's dig in a little bit deeper. So this is all the steps of cellular respiration.

Remember we begin with glucose. In glycolysis we break that down into pyruvate. How much

energy do we get from that? We get 2 ATP. Now we put in some ATP, but we net a total

of 2 ATP. What happens to the pyruvate? It's going to go into the mitochondria. It enters

into the Kreb Cycle after it's converted to acetyl COA. We give off all of that carbon

as carbon dioxide. And we make another 2 ATP. And so we haven't released that much energy

yet. Where did the energy go? It's stored in NADH and FADH2. They're going to transfer

their electrons through the electron transport chain. Eventually those electrons go to oxygen

with the formation of water. And we're going to make most of our ATP here. And so we're

going to make somewhere between 32 and 34 ATP. And so we net around 38, but there's

controversy. It's probably not as much as that. But how could we break this process?

Well we could break this process, number one if we didn't have any glucose. But we usually

have enough food inside our body. We could break this in two ways. We could get rid of

the mitochondria. So if there was a toxin that destroyed the mitochondria for example.

Or if we just didn't have enough mitochondria present. Or if we didn't have oxygen. Remember

oxygen is right here at the end. It's receiving those electrons. It's the final electron acceptor.

And if we don't have that, the whole thing kind of backs up. And so we're out of luck.

And we would be out of luck if it weren't for anaerobic respiration. If you want to

feel what anaerobic respiration feels like, just hold your breath for awhile. You're going

to run out of oxygen. You can't make ATP. And you're going to get in some serious trouble

very, very quickly. And so what is the problem? Why are you feeling that pain? Well it really

boils down to glycolysis. And so in glycolysis we're taking glucose. And we're breaking it

down into pyruvate. Remember we net 2 ATP. Where did that energy go? It's being converted

to NADH. A lot of it is converted to NADH. And so NADH is going to be reduced remember.

It's going to pick-up electrons. But pretty soon all of that NADH is full. There's no

electrons that can be donated to it because it's now all at NADH, or reduced NAD+. And

so that's where we get stuck. And where are we going to come up against this wall if we

don't have oxygen or if we don't have mitochondria. And so what is our solution to that? Well

through evolution we've come up with two solutions to this. We have lactic acid fermentation.

And we have alcoholic fermentation. So first you have to do glycolysis. But after that

in animals and bacteria they do what's called lactic acid fermentation. And so in a sloth

they don't move that fast, but maybe in you when you're sprinting or in bacteria when

they're making yogurt, they can do another process after glycolysis. And what that does

is it allows us to keep doing glycolysis over and over again. And in alcoholic fermentation,

they do that by actually converting it to ethyl alcohol. So let's go through those specifically.

Again, here's where we're stuck. We've gone through glucose or glycolysis. We've made

pyruvate. But now we have all of this NADH. And there's no way that we can keep going

through glycolysis because all of it's filled. And so in lactic acid fermentation what happens

is this pyruvate is converted further into lactate. And sometimes you've maybe heard

of that called lactic acid. What happens with the formation of lactic acid? Well we're not

making any ATP. But those electrons can now be converted from NADH and it can be transferred

to lactate. What does that do? It frees up this NAD+ to go back and pick up more electrons

again. And so what we can do is through this process we can go through glycolysis over

and over and over and over again. And so we can make ATP every time we do that. Now we're

not going to get all that ATP that we would if we went all the way through Kreb Cycle,

Electron Transport Chain. But we can still make quite a bit of energy. Now this is a

picture over here of my son. He is a cross-country skier. And so in this picture right here he's

on a treadmill. He's skiing. And this is a test to calculate VO2 max. To figure out how

efficient you are at using oxygen. But it also is going to measure your lactate threshold.

It's going to measure the amount of, how much exercise you have to do before lactic acid

builds up in your muscles in an appreciable amount. And so if you were exercising really

really quickly, you get certain amount of energy through cellular respiration. But if

you go faster and faster and faster eventually your body will also add on top of that this

lactate acid fermentation. And if you've ever run for example a 400 m dash or sprint, that

pain you feel in your muscles is a build up of this lactate in your muscles. And so eventually

that's not even enough. And you're eventually going to just have to stop running or stop

competing because it's too painful. And that's that build up inside your muscles. And so

what happens is after you're done you have go through and breath a lot. And then use

oxygen and cellular respiration to breakdown that lactate. But it does give us kind of

like a turbo boost to go on top of that regular cellular respiration. Bacteria do the same

thing. If you were to put them in milk for example, lactobacillus bacteria will go through

lactic acid fermentation. And that acid breaks down the proteins in the milk and makes yogurt.

And so that's one way that we can survive when we don't have oxygen. Lactic acid fermentation.

Remember, it still includes glycolysis, but it's followed by this lactic acid fermentation

so we can go through that process. Now we also see the same thing in alcoholic fermentation.

And so where would we see that? That's going to be in things like yeast. And so what are

they doing? They're breaking down glucose into pyruvate. But again they're stuck. And

so for example if we put a little bit of yeast and some grain and sugar in this bottle, they're

going to start to do cellular respiration. Just like we do. But eventually they're going

to run out of oxygen. No oxygen can get in this container. Only gas can get out. And

so eventually they're stuck. And they would be stuck if they couldn't do fermentation.

What are they going to do? They're going to convert that pyruvate into ethyl alcohol.

That's the alcohol that we'd find in beer and wine. Now if you look at pyruvate and

ethyl alcohol, we're missing a carbon here. And the reason why is that that carbon is

going to go towards carbon dioxide. That's why we have a build up of this carbon dioxide

in beer or champagne for example. What is that doing though? Again it's the same thing.

It's picking up electrons from NADH. And that's producing more of this NAD+. And so we can

go through that process of glycolysis over and over and over again. And so if we're looking

at yeast inside here, now they'll do alcoholic fermentation. And they'll do that until they

have consumed, built up too much of this ethyl alcohol. And then it will eventually poison

them. And so we've known this for a long period of time. And so fermentation has being going

on for years and years and years. The Egyptians used to make beer using fermentation. And

we do it today as well. So what do you need? All you do is put a little bit of grain in

there, some sugar water and some yeast. If you don't given them oxygen eventually they're

going to convert to alcoholic fermentation. And they'll do that until the level of alcohol

inside there is going to kill the yeast. They settle to the bottom and then we have alcohol.

And so that's anaerobic respiration. What does in do? It allows us to keep going if

we have no oxygen or no mitochondria present. It only lasts for a certain period of time.

And then we're out of luck. And I hope that was helpful.