At how many places in Krebs cycle , FADH2 is / are formed ?
Answers
we already know that if we start off with a glucose molecule we start off with a glucose molecule which is a six carbon molecule six carbon molecule that this essentially gets split in half by glycolysis and we end up with two pyruvic acids or two pyruvate molecules so glycolysis literally splits this in half it Lysa's the glucose and we end up with two pyruvates or pyruvic acids pyruvate and these are three carbon molecules three carbon molecules there's obviously a lot of other stuff going on in the carbons you saw in the past and you can look up their chemical structures on on the internet or Wikipedia and see them in detail but this is kind of important thing is that it was it was lysed it was cut in half and this is what happened in glycolysis glycolysis glycolysis and this happened in the absence of oxygen or not necessarily it can happen in within the presence or in the absence of oxygen it doesn't need oxygen and we got a net payoff of two ATP's two ATP's net and I always say the net there because you remember it used to ATP's in kind of that investment stage and then it generated four so it's on a net basis it generated four used to it gave us two ATP's and it also produced two nadh --is two na DHS that's what we got out of glycolysis and just so you can visualize this a little bit better let me draw a cell right here maybe I'll draw it down here let's say I have a cell that's its outer membrane maybe its nucleus we're dealing with the eukaryotic cell doesn't have to be the case it has this DNA and it's chromatin form all spread around like that and then you have some mitochondria and you know there's a reason why people call it the power centers of the cell we'll we'll look at that in a second so this is a mitochondria has an outer membrane an inner membrane just like that I'll do more detail on the structure of a mitochondria maybe later in this video or maybe I'll do a whole video on them that's another mitochondria right there and then all of this fluidic space out here that's between the organelles or in the organelles you kind of view them as parts of the cell that all right you know they do specific things they do specific things kind of like organs do specific things within our own bodies so this so between all of the organelles you have just this fluidic space this is just fluid of the cell and that's called a cytoplasm cytoplasm and that's where glycolysis occurs so the glycolysis occurs in the cytoplasm glycolysis now we all know I've in the overview video we we know what the next step is it's the Krebs cycle or the citric acid cycle and that actually takes place in the inner membrane there were the inner I shouldn't say the inner space the inner space of these mitochondria let me draw it a little bit bigger let me draw up mitochondria here so if this is a mitochondria it has an outer membrane it has an inner membrane if I have just one inner membrane we call it a crista if we have many we call them cristae these little convoluted inner membrane you give it a label I'll say there cristae plural and then it has two compartments right it's because it's divided by these two membranes this compartment right here is called the outer compartment this whole thing right there that's the outer compartment and then this inner compartment in here this inner compartment in here is called the matrix the inner compartment right there is called the matrix now you have these pyruvates they're not quite just ready for the Krebs cycle but I guess well it's a good it's a good intro into what how do you make them ready for the Krebs cycle they actually get oxidized and I'll just focus on one of these pyruvates we just have to remember that the pyruvate that this happens twice for every molecule of glucose so we have this kind of preparation step step four for the Krebs cycle we call that pyruvate oxidation pyruvate oxidation and essentially what it does is it Cleaves one of these carbons off of the pyruvate and so you end up with a two carbon compound you don't have just two car but this backbone of carbons is just two carbons called acetyl co a acetyl co a and if these names are confusing because you know what's acetyl coenzyme a these are very bizarre you can do a web search on it but I'm just going to use the words right now because it'll keep things simple and look at the big picture so it generates a siedel Kawai which is this two carbon compound it also it also reduces some NAD+ to NADH and this process right here is often a given credit or or the krebs cycle of the citric acid cycle gets credit for this step but it's really a preparation step for the krebs cycle now once you have this two carbon once