Glycolysis and Fermentation (updated)

okay so today's topic will be on fermentation you know we're gonna start by making sense out of this diagram right here so as we go through this presentation we're gonna talk about a variety of cellular reactions and chemical reactions and one thing I'd want to just remind you the whole purpose of these chemical reactions is gonna be to make a molecule called adenosine triphosphate ATP this is the energy molecule needed by our cells so how cells make ATP and their energy well it depends on a few certain factors and that's what we're gonna talk about right now aerobic versus anaerobic respiration so when we go through fermentation you know before we actually discuss fermentation we need to talk about what glycolysis is glycolysis is a chemical reaction where a molecule of glucose will be broken down into a couple molecules called pyruvate that is a very short symbolic diagram of what happens during glycolysis well what about those pyruvates that are left over well there's two pathways that will happen next one pathway is anaerobic pathway and one pathway is an anaerobic pathway so let's follow the aerobic pathway first if oxygen is present then those pyruvates generally will head to the mitochondria and within the mitochondria is where the Krebs cycle occurs and then following the krebs cycle the electron transport chain and these steps glycolysis the Krebs cycle the electron transport chain generally make a lot of ATP one molecule of glucose can make anywhere from 36 to 38 molecules of ATP this is viewed as the aerobic pathway the pathway that the cell typically follows with the presence of oxygen however there's an anaerobic pathway sometimes cells are devoid or without oxygen and in that case the pyruvates that are left over when glycolysis is finished be used and broken down into either lactic acid or ethyl alcohol depending on the type of fermentation that occurs and once these two products lactic acid or ethyl alcohol have been created that will allow the lye calluses to restart over and over and over and the cell gets caught up in this loop of performing glycolysis and fermentation that's what we're going to talk about specifically today so let's start by breaking down glycolysis this is the chemical process that starts in the cytoplasm and what happens is a molecule of glucose gets broken down by molecules of ATP nad and a variety of enzymes now for simplicity I've drawn glucose as the six blue C's arranged in hexagons formation now in reality there's also 12 hydrogen's and six oxygens but for simplicity I've only drawn the six carbons of glucose and so what's gonna happen is two molecules of ATP are gonna begin to break down that glucose with the help of various enzymes so here's a molecule of ATP and my scissors represent one of the enzymes and when the ATP molecule gets broken the glucose is broken down into this intermediate molecule right here now this intermediate molecule doesn't last very long because a second molecule of ATP and a different enzyme once the ATP is broken down energy is released and that intermediate gets broken down into a couple molecules which I'm just gonna call P gal fossil glyceraldehydes notice how each of them are three carbon molecules well originally this was a molecule of glucose which had six carbons so next enzymes which are in the cytoplasm will add another phosphate onto each of the P gals so here's an enzyme the scissors adding a phosphate to the P gal on the left and and the phosphate being added to the P gal on the right and by doing this this converts the P gal into another intermediate molecule so next a couple molecules abbreviated NADH will be created now NADH starts out as a molecule called an ad or nad and nad stands for nicotinamide adenine dinucleotide so just for ease and simplicity I'm gonna just call it mad and what happens is of course there's enzymes involved I just didn't show the enzyme but nad will strip off a hydrogen and generally we'll carry that hydrogen over to the mitochondria now this happens on the right side as well the other nad will strip off a hydrogen and generally will usually carry it over to the mitochondria next so now that we're near the end of glycolysis let's focus on those four yellow peas that I've drawn those represent phosphate groups now I've also just added four molecules of ADP and what happens is an ADP molecule along with an enzyme will break off one of those phosphates to make a molecule of ATP now this will happen three more times a molecule of EDP along with an enzyme will break off one of those phosphates to make ATP and ADP with the help of an enzyme will strip off a phosphate to make ATP and an ADP along with the help of enzymes will strip off a phosphate to make ATP and so notice what we're left with two molecules labeled pyruvate now those that when we began we had a molecule of glucose now it's left over these molecules of pyruvate these are gonna be really important when we move on into fermentation next notice also four molecules of ATP were created but we say a net gain glycolysis makes a net gain of two ATP's why well even though glycolysis made four in the end two ATP's were started were used two ATP's were used to start the process of glycolysis so when you subtract the two that were required to start from the four that were created we say a net gain of two ATP molecules was created well now let's move on into fermentation well there's actually two kinds of fermentation and we're gonna start with lactic acid fermentation this is the fermentation performed by animals such as bears and humans and as well also this fermentation lactic acid fermentation is performed by microscopic bacteria and when we think about bacteria we actually use the lactic acid fermentation process of bacteria to make many food products it's for instance it's what gives sourdough bread its distinct flavor we also use the back certain species of bacteria in the process of fermenting cucumbers in order to make pickles and in the production of yogurt it's what gives yogurt its it's kind of sour taste to it because the bacteria produce lactic acid which has a sour taste and so let's go into that cellular process next okay so lactic acid fermentation occurs in the cytoplasm of cells and it occurs when cells do not receive enough oxygen in order to perform the Krebs cycle and the electron transport chain which is what cells would prefer to do the krebs cycle and the electron transport chain make a large amount of ATP but in order to do this the cell needs and the mitochondria specifically needs oxygen but there are times when cells don't have enough oxygen and so they have to perform lactic acid fermentation now you might be thinking about why would a cell not have oxygen well for instance you know there's a problem during exercise or let's say you're playing a sporting activity sporting contest your muscles need a lot of ATP because they're working really hard well solution is why don't you just make more ATP after all you can break down your glucose in your body to make more ATP that seems like a pretty obvious solution right well there's a new problem oxygen is needed to produce the vast amounts of ATP through the crowd cycle and the electron transport chain but because you're involved in exercise or you're playing a sporting activity your muscles are working really hard so they're actually deprived of oxygen your muscles aren't getting enough oxygen so you could stop but that would defeat the purpose of exercise and if you're in the middle of a sporting contest you're not going to just stop in the middle of the court or the field and let the soccer players go around doing the basketball players go around here you're not gonna just stop you're gonna keep continuing I hope so there's a new solution here is that fermentation allows the cells to make ATP without the use of oxygen and let's explain that so fermentation occurs after glycolysis and when we left off we had the NADH go to the mitochondria but I'm gonna get rid of the mitochondria in my animation not because the mitochondria is disappeared because but because it's not involved in this process without oxygen everything stays in the cytoplasm and what's gonna happen is those two pyruvate so let's focus on the pyruvate to the left it's gonna gain a hydrogen from NADH and enzyme represented by my scissors we'll bring together the pyruvate and the NADH and the pyruvate will strip off a hydrogen creating nad well now that the pyruvate has the hydrogen it's not called pyruvate anymore it's now called lactic acid and notice how a molecule of nad was recreated well this happens in the other pyruvate as well here's another pair of scissors representing an enzyme and NADH and the enzyme and the pyruvate are joined together and the pyruvate strips off a hydrogen creating lactic acid two molecules of lactic acid that begins to build up and that's what causes that familiar soreness as we continue to exercise and you know work our muscles really hard so now that the lactic acids been created its release as a waste and as I said a moment ago begins to build up and it accumulates in our muscle and that's what causes that familiar burning sensation whenever we go up a lot of stairs or were involved in heavy exercise that burning in our muscles well that's from the accumulation of lactic acid well let's finish off lactic acid fermentation why is the NAD so important well it helps to restart glycolysis here's a new molecule of glucose and glucose can be broken down with the help of ATP with enzymes and with nad and when that happens molecules of ATP get created but if I were to ask you how much ATP is actually created through fermentation I hope you know the answer is zero fermentation does not make any ATP it makes some lactic acid waste but more importantly it makes nad and NADH realm of glycolysis well how much ATP is made through glycolysis well you can say a total of four ATP's or you can say a net gain of two because two ATP's are required to start glycolysis you know while we're on the topic I might as well bring up a few ways to help recover from an exercise you know after exercise you might be a little sore so you know good ways to relieve maybe some of the soreness would be through massage whether it's through a professional masseuse or using a foam roller to kind of give yourself a massage also eating bananas which are high in potassium potassium is really important in your muscles ability to stretch and contract so eating bananas is a key nutrient in muscle recovery proper hydration not just during your activity but pre and during and post-workout properly hydrating yourself is one of the keys to you know reducing it and preventing soreness in the first place and also performing a post stretch I think most people know to do a pre stretch before you perform any vigorous activity but a lot of people don't always think about a post stretch and it's one of the better ways to help relieve muscle soreness so as we shift focus to the other kind of fermentation alcoholic fermentation this is the fermentation generally performed by yeasts which are a type of fungus and they're responsible for the production of alcoholic beverages and for the production of most bread I mentioned sourdough earlier well sourdough is produced by lactic acid fermentation but most other breads are produced through yeast and the actions of alcoholic fermentation so during alcoholic fermentation this process occurs in the cytoplasm and because the mitochondria is not involved I'm gonna remove it from my animation generally speaking this occurs in yeasts and even some plants and so what happens is here's a pair of scissors representing an enzyme and the enzymes gonna break down the pyruvate on the left now remember the pyruvates were just created through glycolysis so here's the enzyme breaking down the pyruvate notice how some carbon dioxide waste was created along with a two carbon intermediate molecule so let's focus on that two carbon intermediate what happens next is NADH well with the help of an enzyme NADH with the help of an enzyme the NADH will actually lose its hydrogen the hydrogen will be stripped off by the two carbon intermediate molecule free up the nad and notice what's left behind is ethanol another name for ethanol is ethyl alcohol it's the alcohol created during fermentation well the same thing is gonna happen to the pyruvate on the right so here's a great time to review these two steps that are in the notes step one says it and as I'm will break down pyruvate well here's an enzyme the enzyme will break down pyruvate and co2 is released this also leaves behind this two carbon intermediate molecule well then we move on to step reviewing step - here's another enzyme and the enzyme along with NADH the NADH will have its hydrogen stripped off by that - carbon intermediate creating an ad and another molecule of ethanol so focus on the ethanol the ethanol is released as a waste and the carbon dioxide was released as a waste so why is alcoholic fermentation important what was created is the nad the nad will help to restart glycolysis so here's another molecule of glucose enzymes plus the nad plus molecules of ATP will break down that glucose to make more ATP oh and by the way if I were to ask you how much ATP is created through alcoholic fermentation again the answer is zero no kind no ATP is made through alcoholic or lactic acid fermentation the purpose of fermentation though is to make those na DS and those na DS will help to restart glycolysis and how much ATP will be created through the light alysus well you can say for a total or a net gain of two you know earlier I mentioned that bread is created by yeast as they perform alcoholic fermentation so what causes bread dough to rise in the baking process well I hope you know the answer is the carbon dioxide as the carbon dioxide is released by the cells of yeast the carbon dioxide gas causes the dough to fluff up and the bread rises well you might be asking if bread is created through alcoholic fermentation well then why isn't bread alcoholic well that's because of the baking process in the process of baking bread the heat from the oven causes the ethanol the alpha alcohol to be burned away and it simply evaporates so as we finish up this video you know here's a real short practice quiz for you to try and you know if you're in my class maybe write your answers on a sheet of paper and I'm happy to check your answers before a score or after school and also leave your comments in the box below I'd love to hear what you thought of this video thanks for watching

Channel: Beverly Biology

Views: 42,497

Keywords: Biology, Cells, Chemical reaction, Glycolysis, Alcoholic fermentation, Lactic acid fermentation, Glucose, Cellular respiration, Anaerobic, Aerboic, Mitochondria, ATP, Adenosine triphosphate, Pyruvate, Krebs cycle, Electron transport chain, NAD, NADH

Id: 1LnImHzjamw

Length: 18min 32sec (1112 seconds)

Published: Sat Jun 16 2018