Cellular Respiration | Summary

good morning um this video is going to be a summary of cellular respiration so make sure you have your pens ready and let's go ahead and hit it when i'm all done i'll i'll zoom out one more time for you okay so um this video is intended to be a review for a student that maybe has already heard a lecture on the various parts of cellular respiration and it would be particularly useful if you were preparing for something like the teas test which is a test students have to take to get into a nursing program i'll go over the basics and i will tell you though to be perfectly honest i found this topic to be pretty tricky to make you a good summary so here we go i will do my best okay all right so i want to start um over here and we'll just draw a blood vessel and this is a reminder that the nutrients the carbon sources that are needed in order to do cellular respiration are coming from the blood the main one we'll focus on is glucose so glucose would be delivered to this cell through the blood and i'm using red for this um and then we're i'm actually uh going to make like a little line right here actually let's do that in um maybe like a blue that would be better to do this and that indicates that now the glucose has come into the cell so this would be the cell membrane and this is a blood vessel sorry and so the glucose can come into the cell and then it will be in the cytoplasm and then every cell in the world i'm not kidding you whether it is can do this process called glycolysis and break this down into pyruvate whether it is a bacterial cell a fungal cell a protist a plant or an animal every single cell can do this and that's why we're making this in red because it's such a big deal so glucose is broken down into something called pyruvate or sometimes it's called pyruvic acid and don't worry those mean the same thing for our purposes because we're pretty basic here okay so glucose has six carbons in it and we can do those with these little circles and connect them so six carbons pyruvate only has three so it probably wouldn't surprise you that if you break glucose down into pyruvate you're actually going to end up with two of these and in that this process then let's put a box around it and i want to make sure that you're comfortable that the name of this process is glycolysis because it is the first part of cellular respiration let's use a black pen to write glycolysis here this process is called glycolysis and notice that it occurs in the cytoplasm and notice that it does not require um oxygen so it occurs in the cytoplasm and no oxygen required so this is anaerobic so those are a couple of things that you might be asked about this where does it occur it occurs in the cytoplasm which cells can do it all cells can do it and is oxygen required nope so this is what you can do when you're sprinting uh there's a couple other even quicker ways but i'm not going into that in this video but anyway this is going to be a really good source for sprinting because you don't need any oxygen in order to make the pyruvate then of course the reason it's useful let's go ahead and use orange oh no pink no uh yeah orange so we do get our cells do make um a couple of atp from this process and atp is the cellular energy currency that our cells use they use atp to make the pumps work like to put things in and out of cells they use the atp to fire action potentials to maintain the membrane potential so it's ready to fire an action potential all of this stuff requires atp so just think of this as fuel for your cells but our body has to convert carbon-based fuels into atp okay so if there is still no um oxygen available then this pyruvate will get converted into something else called lactic acid and this also is known as lactate and again for our purposes that's general enough now this is a waste product that our bodies need to get rid of and so we're going to put that over here on our picture we'll write lactic acid this is a waste product and because of its acidic nature and so it has to go into the bloodstream if you'd like you could maybe highlight this blood vessel in pink and um so if you are doing a lot of anaerobic exercise you will feel the burn because that this will lower the ph of your blood and cause a stinging sensation on nerve endings and this is why um as you work out well and i should say as you get in better shape you can tolerate higher levels of this lactic acid and our bodies do have ways of interconverting it too which are also beyond the scope of our video here but so this would be um this process of pyruvate to lactic acid if there's not any oxygen around is called fermentation now fermentation is a fun thing to talk about in bacteria too because lactobacillus do this they make lactic acid and that's why yogurt is sour and bacteria or sorry yeast like saccharomyces cerevisiae can ferment to form ethanol so all alcoholic beverages are a fermentation process so a lot of the foods we eat are fermented a lot of the healthiest foods that we eat are fermented but our animal cells can do it as well when there's not oxygen around and then that lactic acid needs to be gotten into the bloodstream as a waste product so this would be if there was no oxygen so if though there is oxygen available then the pyruvate can be shuttled into the mitochondria so let's go ahead and label this as the mitochondria and when it's individual singular we say mitochondrion you notice that it has an inner membrane yeah it's double it has a double membrane and then this space in between is the inter membrane space right right in here and then this inner part here so this is the inner membrane is called the matrix in here the matrix okay so what's going to happen next and we'll continue to use red because this is the main pathway is that the pyruvate will then get converted into something called acetyl coa and this is the starting point for a process known as the krebs cycle so get your black pen again so glycolysis was the first part that students are usually asked about when they're needing to know about this process then the next one this is called the citric acid cycle once in a while in your books you might see it called the krebs cycle that's the guy that figured out a lot of the pro steps in this process and then it seems like it's more popular nowadays also to call it the tca cycle that's one of the chemicals that's involved so you have these intermediates that acetyl coa gets its two carbons get added to and this process just kind of goes around and around but acetyl coa is the adding of the carbon sources and then this cycle just keeps turning turning as long as oxygen is present which won't come into play for a little while but this the oxygen basically is what makes sure this thing keeps turning turning and then fuel sources come in as acetyl coa so um the whole purpose of this this process is to gather the electrons that are on those carbons and i use the e um like this that's that's for electrons maybe i'll write that out for you in case you haven't seen that lingo so gather the electrons from the carbon source and the carbon source that starts out is acetyl-coa so acetyl-coa has two carbons remember we started out with glucose that has six so maybe it doesn't surprise you you kind of crank this thing around three times for every glucose that comes through or two times sorry because you lose a carbon here sorry i meant two times um and you get a little bit of atp from cranking this thing around and so let's go ahead and put that right here so we get another couple and remember atp is your cellular fuel source it's what makes everything happen it is the reason that all of your cells can keep doing the different activities that they do so by breaking down glucose we got a couple of atp from glycolysis and then a couple from the krebs cycle and then we also get a waste product here so i used lactic acid why don't i put um that in green these the waste product so like let's highlight lactic acid here in green and then also right here and now we're going to make another waste product carbon dioxide because as you break apart those um carbons in order to gather up their electrons now the carbons are blown off and that's this is a waste product that then needs to go out through the bloodstream and then you blow it off when you breathe so so we have waste product number one is lactic acid and then another one is carbon dioxide or co2 and that also needs to be transported away and this came from the citric acid cycle so that's where we generate the carbon dioxide and then the lactic acid is from fermentation okay so the next thing is that we need to draw our electron carriers so remember that the purpose of the citric acid cycle is to take the carbons break them apart in such a way that you can gather the electrons onto and we often use like trucks to do this i'm going to draw you a little truck you can do this you can draw this look it okay put some wheels on your truck and then put an electron that it's carrying and this truck would be that's like a window um is what we call nadh and it's going to take its electron over to the electron transport system and then we have some some students will get asked this i don't usually make a big deal of it with my students but you might get asked about the other electron carrier that's involved here and that is f a dh2 and all i think it's important for you to understand is that these are compounds that when the electrons are popped off the carbons these molecules nad plus can pick up this this and then fadh picks up the hydrogen 2 or in the electron and carries it over to the electron transport chain so we call these electron carriers and then they drop off their electron here and then they go back but when they go back now this would be um nad plus after it's dropped it off and this would be f a d h so these are what they're called before they pick up an electron and then they pick up the electrons and they just keep doing this so they take the electrons to the electron transport chain so this process this next one is called the electron transport chain and it's made up of these proteins that are embedded in the inner membrane of the mitochondria so notice the krebs cycle happens in the mitochondrion so does the electron transport chain but glycolysis remember happened out here so let's go ahead and put like a red box here and this would be the second step assuming oxygen is available and then the third step would be electron transport chain so now this is where it's like the show me the money stage this is going to be really awesome what happens here so after these electron carriers drop off their electrons each time the electron i think i'm going to switch to blue here each time the electron pops to the next protein in the line because these are increasingly electromagnetic meaning they pull the electrons a hydrogen ion gets pumped out into this inner membrane space so why don't we use purple for the electron and watch it it gets popped to the next one and that provides the next transporter with energy to pump a proton out and this is going to generate a proton gradient proton is just another name for hydrogen in this context and when i say gradient what i mean is there's going to be more hydrogens out here than in the matrix so guess what they're going to want to come back in and look this is where they're going to get it come back in and we'll tell you about that so the electrons get popped along and each time they get popped along they're like oh i have a little bit of energy i'm gonna pump out a hydrogen oh i have a little bit of energy i'm going to pump out a hydrogen so the purpose of the electron transport chain at this point is to generate the proton gradient why don't we put that here so we generate a proton and i'll just put a hydrogen gradient maybe i'm running out of room a little bit here and then what happens is these electrons get to the end and guess what this is where oxygen finally gets its turn um what color have i not used very well i used a little bit of orange there well how about we just keep with the purple because guess who's going to gather up these electrons is the oxygen so what happens here is that oxygen is even more electronegative than these proteins so it like sucks the electrons to it and then meanwhile the hydrogens are finally allowed to come back through and guess who grabs them oxygen grabs them because if it's getting these electrons that have a negative charge it can balance them with the hydrogen and we get the production of water and so now that also balances out it means that oxygen can then be neutral and not have too many electrons or too many hydrogens but that's not the end of the story so okay i should say though yes hydrogen or water is a product of cellular respiration but we don't make enough of it so that we wouldn't need to drink water we still need to drink water but my favorite part of this story is that so see how we have all these hydrogens out here that want to come back in well this molecule right here is called atp synthase and i think all use um oh you know what i should have used green for the water because even though it's not a waste product it is a product that way um and this is called atp synthase and i think all boy i'm having a hard time deciding on my colors today aren't i why don't i make it um how about just red because this is a part of the key part here so this is atp synthase and see so what do you think it's going to synthesize it's going to synthesize atp it uses the rushing energy of those hydrogens coming through and it turns like a machine to generate atp so let's go ahead and use orange so it converts adp it uses that moving energy to make atp and we usually say it makes about 32 it can vary so don't get too hung up on that but what you would need to know typically in a class is first of all this electron transport chain is the most useful at making atp look at how many it makes as opposed to glycolysis so you can do this for a while when you don't have enough oxygen available but this is where you're really going to show me the money kind of thing so we've got glycolysis krebs cycle or citric acid cycle and then electron transport chain so it generates the hydrogen gradient it uses the moving hydrogens when they get to rush back in to put or i should say to build atp and that's the purpose there and then if we at the bottom just write the equation for cellular respiration you've got glucose plus oxygen yields carbon dioxide as you break apart those carbon fuel sources um a little bit of water not enough so that we don't need to drink water but a little bit and then a whole bunch of atp that's the goal so why don't we highlight the atp and that's why we call the mitochondria our powerhouse because it is where we get um all of our atp energy from for the most part i mean you can do in the cytoplasm this small amount here and why don't we highlight this equation in pink or just put maybe like a box around it so that when you're reviewing you can be like okay here's the equation this is what's going on as you can see i didn't worry too much about like numbers of things in this i really want you to see the big picture and um i amazingly think that this went pretty smoothly i do want to now um what i'll do is i'll back off so if you feel like this is all you needed for your review you've got your three processes then i think you're good however i want to spend a couple more minutes talking about other carbon fuel sources so um fatty acids are an amazing fuel source and i think i'll use um maybe just purple to talk about that so i want to talk about fatty acids as a fuel source now glucose has six carbons guess how many um fatty acids have they have like 16 to 18 usually that's the most common number but they can be different sizes let me just make sure i have my af lock on okay it says i have the af lock on so these fatty acids can come again from the blood and then they can be also converted into acetyl co a but imagine how many acetyl coas you can make from something that had 18 carbons and that is why if you can become a fat burner you can run all day because you can take these fatty acids and we all have even thin people have a fair amount of fat on their body to use and then they can just keep cranking out the atp all the live long day if you are just a sugar burner then you might hit the wall a little bit sooner um on a typical activity um of course if you're trying to do something super intense though you're always relying just on glucose okay then another great source is uh ketones everybody's heard well i shouldn't say everybody but most people have heard about ketone bodies or ketones at this point and these are actually a breakdown product of fatty acids they usually have three or four carbons so they're a quick fuel source if you start making them and guess what they can get converted into acetyl coa so if you hear about someone that is in ketosis what it means is their body their liver has gotten good at making these and now they have this additional and alternative fuel source if there's not enough glucose available it's particularly well known to be useful in the brain because the brain mostly relies on glucose but if there's something wrong with the enzymes needed in this pathway then ketones can be a substitute so it's something they're looking at a little bit in diseases like alzheimer's parkinson's and of course well-established like seizure disorders okay then i want to tell you one more carbon fuel and that would be deaminated amino acids so let's go ahead and put them right here now an amino acid just like it sounds is has an amine group it has a nitrogen and amino acids are used to build proteins and mostly we use those structurally like to build the different parts of your body but your body can also use these as a fuel source to make atp can do it no problem a few amino acids can just be converted into pyruvate but most of the amino acids will be somehow brought into the krebs cycle either being converted into acetyl coa or even like one of the intermediates in that cycle so amino acids are all different lengths some of them only have like three carbons some of them i think might have as many as 11 but you can see that what we really are looking for with the fuel is carbons so oh i should have put carbons here you can have fatty acids which are going to give you you know basically unlimited carbon source ketones a quick alternative fuel glucose a very very quick uh primary fuel and then deaminated amino acids i put this word deaminated because you have to remove the nitrogen so all you have left is like the carbon backbone and then that's what is going to end up providing the carbons that can crank that krebs cycle around and then remember your goal is to gather up the electrons onto these electron carriers the electron carriers then go take that over to the electron transport chain and the movement of the electrons makes a hydrogen gradient and then guess what you're going to harness that hydrogen gradient by using it's like this it's like this whoosh and then the atp synthase is able to make uh atp for your body okay i'll zoom out one more time and i think that went pretty well take care everybody it's a sunny day here today i'm staining my fence and i'm ready to get back to it take care

Channel: Science with Susanna

Views: 47,411

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Id: GLr4YGHtong

Length: 26min 2sec (1562 seconds)

Published: Tue Jul 14 2020