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Course: Class 10 Biology (India) > Unit 1
Lesson 5: RespirationAerobic & anaerobic respiration
Lets explore cellular respiration (Aerobic & anaerobic). Created by Mahesh Shenoy.
Want to join the conversation?
- Can I get your class code for google classroom
if you are there, Sir(11 votes) - does bread contain alcohol?(3 votes)
- Yes it can contain but in almost negligible amount since alcohol is also a by product of fermentation.(7 votes)
- why do cells need oxygen to break down glucose?(3 votes)
- Cells do not need oxygen to break down glucose. Even anaerobic organisms such as yeast can break down these carbohydrates without oxygen present. The reason oxygen is needed in respiration is to generate energy (aerobic respiration). For example, during the electron transport chain, as the electrons travel through the cascade of proteins, oxygen acts as an electron acceptor. Without oxygen, aerobic respiration cannot be done. Glycolysis, which is a process that uses glucose to produce ATP from ADP and inorganic phosphate (as well as NADH and pyruvate) does not require oxygen. In essence, the reason we need oxygen is to fuel AEROBIC respiration, which generates a lot more energy than anaerobic respiration.(3 votes)
- I was thinking, is alcohol really that bad for body?(Ofcourse, I'm not talking about regular drinking)
But yeah, I've not taken a single sip of Alcohol. I'm just asking.(3 votes)- Actually the main reason by which alcohol affects the body physically is the it gets into the blood and as the blood gets filtered in the liver, every time alcohol passes through liver, some of the liver cells get killed. But this happens when you drink lots of alcohol for a long time. The amount of alcohol is negligible as most of it is evaporated when it is being baked.(3 votes)
- can lactic acid be released in animals...(0 votes)
- Yes. We can take the example of humans, or developed animals.
We get cramps, due to lactic acid, don't we?(5 votes)
- what are the reactants when the product are formed lactic acid and some little amount of energy(2 votes)
- Reactant will be just glucose which will break down in the presence of enzymes present in cytoplasm.(1 vote)
- So in9:10, U mean our muscles go through fermentation? That's creepy.(2 votes)
- No.Our muscles go through partial fermentation. The Lactic Acid is formed is due Lack of oxygen, not the absence of oxygen.
Lack of oxygen means that oxygen is there, in a small amount.
Absence of oxygen means there is no oxygen.
Hope this helps. :)(1 vote)
- can yeast respirate aerobically?(2 votes)
- If cramps are not caused by the lactic acid by anaerobic respiration, then how does it happen?(1 vote)
- You see, when you make a lego engine (by which I mean car engine) after a certain point the engine breaks down since it can't resist the kinetic energy that's flowing through it. So maybe after a few heavy exercises our tendons get overlapped and give us pain. Oooh! Owww!!(2 votes)
- Why do you(or he) says that 'almost' everything you do come from that energy? I don't understand what do you(or he) mean by almost.(1 vote)
- Your heart produces the most electromagnetic waves than any other organ. So it does that in its upper right chamber. In short, the heart has its own energy generator ! That's freaking awesome!(2 votes)
Video transcript
- [Instructor] Have you wondered why you need to breath
oxygen to stay alive? How does oxygen help our bodies? And what's the connection of this oxygen with the pain that you get sometimes when you are lifting weights
or when you're running, the cramps that we get? How are these things connected? The answer lies in cellular respiration. So what is this? Let me start with what it is not. Respiration reminds me of breathing. But let me tell you, respiration
is not breathing, okay? Even though in our daily terms, we might associate
respiration with breathing but in biology, they're
two different things. So what exactly is respiration then? Well, respiration is a process in which the cells of your body, your cells, release energy, release energy from glucose. From glucose. And in our daily terms, we usually say burning calories, right? That's what we mean. Burning calories is respiration. So this is where your cells are releasing that
energy from the glucose. Now, to be more clear, what does this mean? Here is how I like to think about it. So imagine this is your body. The white dots represent the
glucose inside your cells. Why do you need glucose? Because glucose has energy inside of it but the energy's trapped,
you can't use it now, so to release that energy, your cells carry out
some chemical reactions. They break down that glucose and that's what respiration is. So respiration is where your
cells break down that glucose and release this energy. Think of these yellow dots as energy. And then your body can now use that energy for all the various activities. It's that same energy that
keeps your heart pumping and makes your brain work, almost everything that you
do comes from that energy. And now we can answer
why do we need oxygen? If we go back, these our
glucose molecules, guess what? Cells need oxygen to break that glucose. So this is where oxygen
comes into picture. So when we breathe oxygen, the oxygen goes to all the cells. Then the cells use oxygen
to break that glucose and release energy, okay? So why do we need to breathe oxygen? Because cells, for respiration, they require oxygen to break the glucose. So let's write this down
as a chemical reaction now. So what do you think are the
reactants for this reaction? Well, we saw that we need
glucose, so let's write that. Glucose is C6H12O6. This is the molecule of glucose and we saw that cells also require oxygen. They also need oxygen. So this is what they're taking and then what did we see? What happens? We saw that the oxygen
reacts with glucose, it gets broken down and
energy is released, right? So what do we get when we break glucose in the presence of oxygen? Well, we get carbon dioxide. Carbon dioxide is the gas
that we throw out of our body, we exhale that because we don't need it and we also get water. Water is useful for the
body and all the cells, so water is retained and most importantly, we get energy. This is the energy that
you saw in the animation. And you may have to balance this equation which I'm pretty sure you
can do all by yourself but anyways, this is our
equation of respiration. Now, how do you remember this? Well, here's a trick. If you look at this equation carefully, it's a little familiar. This is the reverse of photosynthesis. Remember, photosynthesis? That was where plants and all the green things
will take up carbon dioxide and water and the energy from the sunlight and use it to manufacture glucose and give out oxygen, right? So respiration is the
exact opposite of that. So in photosynthesis,
plants trap the energy from the sun into glucose and respiration is the exact opposite. They release that energy from glucose. And we've talked a lot about how to remember the
photosynthesis equation in a previous video on photosynthesis, so if you need a refresher, great idea to go back and watch that. Anyways, plants also need oxygen to release their energy. I should think plants
only need carbon dioxide but they also need oxygen remember. And similarly, your cells also need oxygen to release that energy and since this is happening right now, it's that same energy that's
allowing your body to function and allows you to do all the work and it's the same energy that's allowing me to walk right now by contracting and relaxing
the muscles of my body. Now, since walking is slow, this energy is sufficient but what happens when I start running? Well, you can imagine as I start running, I spend this energy faster. That means these reactions now have to be carried out faster to give me more energy, right? So that requires a lot of glucose and a lot more of oxygen. Now, glucose is fine because
we have a lot of glucose in our body, so there's no problem with it because I ate a lot of food. But what about oxygen? Oxygen comes from outside
of our body, right? So our cells start
demanding now, they say, "We need oxygen faster, faster, faster. "I need more oxygen faster." And therefore the brain will say, "Okay, okay, fine, I'll give
it to you, I'll give it to you" and brain forces you to breathe shallow, make you breathe faster, right? And that's why we do
this shallow breathing. (instructor panting) Why do we do that? Because I want to get that oxygen fast and I want to release that carbon dioxide from my body very fast. And so because of the shallow breathing, because of this, the
shallow breathing starts but guess what? Even that is not enough for
the core cells over here. You see, the core muscles of my legs are doing the maximum
amount of work in running and so the cells over
there need to release a lot of energy and even with
that shallow breathing, the cells are saying,
"No, this is not enough. "I need oxygen even faster, even faster." And the brain says, "I can't give you "that oxygen that faster. "We can't breath that
fast, that's not possible." So what to do because
they need that energy. So the cells now start
doing at a desperate attempt of getting energy, they start conducting a
different kind of respiration. They start breaking down
that glucose without oxygen. So let's look at the reaction where glucose is broken
down without oxygen. And so when there is
lack of supply of oxygen, some of the glucose molecules
get broken without oxygen and you know what we'll get? This time we'll not get this because this needs oxygen. We will get one product, lactic acid. That's what we'll get. Lactic acid and it releases some energy. Energy. And now you might see I'm writing energy very small over here. You may not be able to see that also and the reason is the energy
released is very small compared to over here. Okay? And so that's why this kind
of respiration definitely is not all that great but it's a desperate situation. Oxygen supply is very low and so some glucose
molecules are broken this way to give that extra energy. This is what gives you that boost. Okay? And if you keep on working out, then this reaction keeps on happening and as a result, lactic
acid starts getting built up in your muscles. So when I'm running, a lot
of lactic acid gets built up in my legs and it's that lactic acid that
makes those muscles acidic and causes that burn and causes that pain and sometimes it also causes cramps. So it's the lactic acid
that does that, okay? Now of course, recent studies show what lactic acid may not be the culprit but our syllabus has not caught up with the recent studies, so in your exams, if they
ask you what causes cramps in athletes, our answer is
gonna be lactic acid, okay? And so now you can see your cells can break down glucose
in two different ways. One by using oxygen and one without oxygen. So we need to give them names. The one where oxygen is used, we call that as aerobic respiration. So this is called aerobic and the word aerobic kind of
means in the presence of air and air here refers to oxygen. And since this respiration
does not involve oxygen in it, it is called anaerobic, so it's called anaerobic, without oxygen or it's also called, it's also got another name, it's called fermentation. They're both same things. Fermentation. So this needs no oxygen,
that's a great thing but it builds up lactic acid and very little energy's produces. Now lastly, there is another possibility for anaerobic respiration which we, our muscles
cells, our cells can't do it but some microorganisms and fungi, the most famous one is yeast, so this happens in yeast, they can also perform
anaerobic respiration, meaning without oxygen, but they don't get lactic acid. So you know what they do
when they break glucose? They give out carbon dioxide, so they give out carbon dioxide plus a very important
product called ethanol. Ethanol and again, plus energy. If it's respiration, it
has to release energy. Again, very tiny amounts of energy. You may not be able to see this but that's energy, okay? Very small compared to this. Now, what is this ethanol? Now, you learn a lot
about this in chemistry that ethanol is a kind of an alcohol, there are different kinds and this is the one that people consume and so you can see that yeast has a lot of importance in alcohol industry and how do we remember this reaction now? Well, I like to imagine a picture of a bottle of beer. Now, we do not promote
drinking or alcohol or anything but the picture helps to remember
the fermentation of yeast. So they put yeast in this beer, right? And that's what produces the ethanol and the carbon dioxide produces this froth but a more mind-blowing example of this is when I learned that
yeast is used in bread and that's what makes it fluffy. So when they prepare
the dough of that bread, they add some sugar and yeast to it and then they let it sit for a while. The yeast starts breaking down
that glucose from the sugar and causes carbon dioxide
to be released from inside and that carbon dioxide, since it's a gas, it
makes that dough rise. Then they start baking it, maybe by putting it in a oven and once you start heating it, the carbon dioxide gas
starts expanding even more and eventually at a
particular temperature, both of them start escaping from that, leaving behind air spaces and that's the air space
that you see in that bread which makes it spongy and fluffy. Beautiful, right? And so both of these are fermentation or anaerobic reactions. This one is lactic acid fermentation and this one is called
alcohol fermentation. So that's pretty much it. So let's summarize. What did we learn in this video? We saw that respiration in biology is not the same thing as breathing. It is process where cells release energy from glucose and one way of doing that is in the presence of oxygen which we call it aerobic respiration which gives the maximum amount of energy and how do we remember this? I remember this as the opposite or reverse of photosynthesis equation. And then we saw when there
is shortage of oxygen, sometimes our cells can break
down glucose without oxygen. This time we get lactic acid
and little bit of energy. Because this is without oxygen, we'll call this anaerobic or fermentation and the way I remember this equation is I remember that I'm working out, that pain is caused, that
cramps are caused by lactic acid even though it may not be really true, for the sake syllabus, we'll use this. And finally, some other
microorganisms like yeast can undergo a different
kinds of fermentation where they give us carbon
dioxide and ethanol and again, a little bit of energy. And the way I remember
this is I know yeast is used in alcohol industries and it's also used in bread making and that bread dough rises
because of the carbon dioxide gas that gets trapped.