all right guys so this is video uh eight in the biochemistry series we're kind of making our way actually into the krebs cycle and there's a few uh you know there's just a few steps in the krebs cycle that you that you really got to know or kind of keep reminder of and there's a couple of the the pathways that kind of lead into it but we we focus on those in this video and it's all about repetition and continual just to to make sure you get you can tell that story whether it's starting from phenylalanine or starting from glucose going down it's an easy way to remember things and something you can just kind of repetitively play over your head where you're just not starting at random spots you're actually telling a story from the beginning so that's what we try to accomplish in this video and we hope you like it all right guys this question reads a 52 year old homeless male with an unknown past medical history is admitted after being found down in the community having seizure patient is suspected to be going through withdrawals gamma glimmer glutamine transferase is elevated okay gdt based off the information given which of the following reaction steps is most likely to be impaired in this individual so we got this guy having a seizure um but he's homeless now if he's having and he appears to be going through withdrawals okay so the take-home point of this question is you gotta know you got to know kreb's cycle you gotta know the basics of it you know we talked about in in the last video you know glucose going down to pyruvate and you gotta know how peru breaks apart it can either go down here to acetyl coa okay pyruvate dehydrogenase or went to lactate but this question okay and just before i move on is remember what we needed here in this step right for pyruvate dehydrogenase to work we needed tender loving care for nancy right thiamin lipoic acid pantothenic acid which is coa um fad riboflavin nad niacin okay we needed these cofactors for this to work there's two other places so three total where i want you to stay i know that 10 or 11 care for nancy those cofactors i need them okay one of those places is also going to be right here at answer choice b because this is where we have the alpha keto uh glutarate dehydrogenase okay and i need tender loving care for nancy there as well okay so um anyways before we go into that question with krebs cycle guys here's how you're going to memorize this and you know that that you it's that little acronym i think it's in the step one book citrate is krebs starting substrate for making oxaloacetate you know citrate has to citrate all the names but citrate is krebs starting substrate for making oxaloacetate all you really got to know guys is this are these few steps right here you know we got this isocitrate to alpha ketoglutarate okay that's the rate limiting step that's why you got to know that one okay rate limiting so if that doesn't work it doesn't doesn't happen okay and that's positive it's it's negatively regulated by nadh and atp meaning if i already got plenty of that stuff it's going to slow down a little bit positively if i got adp and am p it's going to it's going to kind of ramp it up so and then i have this step the alpha alpha-ketoglutarate step and that's the reason i think that's important is because it's influenced by tender loving care for nancy and then for your purposes i want you to know that the next two steps are going to spit out something okay the next uh two steps which is this succino to succinate is gonna is it's gonna spit out a gtp here and it's gonna spit out an fadh2 there so there's only there's only four steps guys that you really have to know that something happens in krebs but again citrate is krebs starting substrate for making oxaloacetate i go to this step here the isocitrate boom he comes out boom he comes out i lose a carbon so we know they're kind of a uh decarbox you know decarboxylative step um but i and with that we've always been doing this so far we get a little nadh right we need we need to kind of get something out of this but this the isocitrate dehydrogenase rate limiting the alpha ketoglutarate dehydrogenase needs tender loving care born nancy this steps important to other people because it makes my gtp and that's my energy source okay and that's the energy source that we'll kind of learn later it's for the decarboxylation nothing yet well i guess you should know that d decarboxylation ox oxaloacetate to uh fossil phenyl pyruvate okay so and that's kind of going backwards uh it's kind of go up to i guess it's it's going to be up here you know kind of go up to the gluconeogenesis going backwards okay that's the importance of this otherwise for the most part don't care okay and then fadh2 we can use him electron transport so again that's all it is citrate is krebs starting the substrate for making oxido acetate i only care about really four steps in this deal really it's just this one okay i only really care about those because those are the ones that i can kind of play with for test questions and those are the ones you're gonna typically ask you now back to this guy homeless guy going through withdrawals so what are we thinking we are thinking alcohol what are alcoholics due to absorption and all that kind of good stuff what are they deficient in for the most part okay well besides b12 and all the things b1 thymine right it's always that question um you know you gotta kind of supplement but you know sugar and thyme and all that kind of stuff glucose and diamond i'm sorry so we gotta be thinking like wernicke course cough all that kind of stuff um the wernicke's the confusion but the the triad can you know confusion ophthalmoplegia and ataxia but anyways when you see alcoholic think b1 now if i don't have b1 in krebs where's my issue if i don't have b1 if i don't have thiamine where's my issue it's going to be right here right it's going to be answer choice b because that's the tender loving care for nancy if they would have gave test questions with pyruvate dehydrogenase then i'm like well wait a second maybe it could be that one too there's three places and we have to we'll teach about the last one here in just a second but there's three places where this tender loving care for nancy comes into play i want you to know this guys i'm telling you this is it's too easy a test question okay it's too easy because they're going to throw some guy that's been on the street going through withdrawals alcohol is involved and you got to know that it's b1 and then you got to know that b1 is a co-factor for these steps okay this is the biochemistry that they're gonna ask you this one says a newborn is seen five days after delivery and appears very lethargic there's a distinct sweet odor burnt sugar okay so just right there you you must want to stop and say okay i know this is the kind of like maple syrup disease kind of thing okay to the infant's urine which of the falling amino acids would be recommended to be restricted okay in this infant's diet so we know that maple syrup you know the i love i love vermont deal but let's just take a take a little deeper dive because i think it's real important a second ago we said acetyl coa right two carbon and it's going to kind of combine with the four carbon and then we're going to start our whole krebs but this acetyl-coa pretty important because to come in there and kind of make him okay we're gonna use this thing called uh leucine okay and then as we did the whole krebs thing we eventually went around and we had this thing down down here called succino co-a and then you know he kind of kept going so these are the two important players when you when you think like the maple syrup deal i want you to be thinking the top top of krebs and also at the bottom of crabs because there's stuff that kind of comes in that deals with this i love vermont okay the iso leucine the leucine and the valine okay now so this guy the leucine in the presence of alpha keto acid uh dehydrogenase okay which is oxidative decarboxylation can make acetyl coa but what do i need i need tender lovin uh tender loving care for nancy to make that happen okay um and down here i have the iso the the isoleucine and valene again alpha keto acid uh dehydrogenase but here it makes the propional coa which makes methylmelonyl coa which i like kind of planning with because it's it's very good for like be you know we start learning about b12 which makes the succinyl coa okay so but these are the enzymes that are that if you have this maple syrup deal you're going to have a deficiency in the it's a defective breakdown of the amino acids it's an effect of breaking down the branched chain amino acids which are the isoleucine leucine and valine so the problem is with what what enzyme it's the problem is with this alpha-keto acid uh dehydrogenase but the question of this really says which of the following amino acids would be recommended to be restricted in this now so it's a lot simpler than it looks because you just got to know which one of these three isoleucine leucine or uh valine and of course the answer is going to be leucine okay but it's more important that you know a little one step further of how to do this so again you're just creating a picture guys now this picture should start from phenylalanine all the way across it's going to go down you know remember how i said it kind of bumps into frumarate and at some point we're going to tie all this together because you're just going to tell one giant story and you'll get all the questions uh correct now the problem with this maple syrup where you have if you have increased uh branched chain amino acids it's neurotoxic okay neurotoxicity um first few days of life okay but again isoleucine leucine valine maple syrup now in an effort to provide glucose to the peripheral tissues during long periods of starvation which of the following reactions is used as an energy source to convert pyruvate to phospholitol pyruvate now we're thinking what you know that's that's way it's like what are you talking about that's like way up here right we said pyruvate you know pyruvate can make acetyl coa in presence of pyruvate dehydrogenase but for some reason you're telling me that pyruvate i need to make you know an energy source that means i need to kick it back upstairs up top well pyruvate going backwards oxaloacetate and then that kind of goes back kind of skips that state right because one of these steps a second ago was was kind of a well i should say it's like a a one-way trip one you know one one direction it's not there um and this is where our phospho osophenol pyruvate okay i need to go backwards okay i need to kind of go upstream per se but where does the energy from this come now a little bit ago i said look guys all i care about on this whole crab deal is four spots right i like i like you to know this one because it's isocitrate dehydrogenase it's the rate limiting step influenced by how much nadh or how little or more you have it or how much nad you have amp all that kind of good stuff this guy i said you i want you to know the alpha-ketoglutarate dehydrogenase because it's important of tender loving care for nancy and that's influenced by this i think alcoholic the succinct and then i said look the next two steps spit stuff out i said fadh spits stuff out because i can use that in electron transport but i said this guy is going to spit something out too right he's going to spit out gtp and i said what is that thing for because it's the gtp that's going to go up and provide the energy to make this little contraption uh work going backwards so again when you're learning krebs all i want you to know is those for those four steps really hear rate limiting here 1011 care for nancy here between succino co-a which is at the bottom add to succinate because it spits out gtp and then this guy because it spits out fadh2 which we can use later and then if we had the phenylalanine you know makes tyrosine we took a right turn he's going to eventually come in here i believe it's going to go into fumarate okay and we can tell the whole story right i mean you could start the story of phenylalanine and also glucose two different starting points and really meet in krebs and keep telling the story and if you do it that way you can actually memorize these things a lot better so the answer to this one is which of the following reactions is used as an energy source to create to convert pyruvate to phospholenol answer choice c okay all right guys hope it was helpful [Music] do [Music] you