hello everyone I'm back again I asked you in our last uh mini lecture to review the cell review its organelles review its structure review a little bit of its uh chemistry this review is going to be paying off for you as we move into further lectures today in our mini lecture we're going to focus on a component of the cell or a process within the cell that process well you you've heard of it in many different forms but we're going to give you the term here cellular metabolism or and or the metabolic pathways the metabolic pathways this set of of chemical reactions and organelles that are dealing with these chemical reactions are providing the cell with a material that it can use as fuel energy much like a car uses gasoline that gasoline in the car has to be processed we can't use crude oil we can't use the other components that make up that Gap so we have to take that crude oil we have to process it in a particular way literally rearranging molecules and bonds so that we have a substance that our car engines our gasoline car engines can utilize can break down those ones use the energy and the breaking of those bonds to get worked up particular types of work done the body is no different so we're going to review these metabolic pathways uh right here to start we need to make sure that you understand glycolysis glycolysis is the first part of this metabolic pathway now the title is actually or the name I should say is actually giving you an idea of what it does in our previous lectures we talked about the molecules of glucose galactose the the monosaccharides that the body uses monosaccharides as our base fuels to rearrange those molecules and create ATP glycolysis is the first step in that glyco meaning glucose meaning those sugars lysis meaning to break to rearrange so glycolysis the breakdown of glucose by enzymes particular enzymes protein enzymes releasing energy okay ATP Empire and pyruvic acid that pyruvic acid is kind of a byproduct of of glycolysis the body does not like wasting things so that pyruvic acid will come into play here now the overall process of glycolysis it is a very elaborate process as you can see here from this diagram up at the upper left hand corner here you can see the glucose molecule we're going to have to burn some energy spend some money here ATP to actually start breaking down glucose we break it down to a particular structure which then will follow a process coming in contact with different in enzymes to rearrange the molecule to make it more I guess you could say susceptible to being utilized as a fuel again as you can see here at the beginning we're actually using ATP we're burning it to help create more energy to help create more energy and as you can see here these two ATP molecules as we move further down the process here and follow it over you know we're giving off particular products nadh and hydrogen ions up here we're giving up here we're actually starting to make ATP so for every ATP molecule we're using here to kind of break down this glucose we're gonna we're gonna make two we're going to make two so in essence we're we're making a little bit by by breaking down this initial part of the glucose now this process this glycolic glycolytic process is very fast it's very very fast so we can create those ATP molecules fairly quickly now I'm not asking you to know all the enzymes in this process I'm not asking you to know every last step in this process that's where your biochemistry class what I do want you to understand is looking at or creating kind of a a nice image for you to kind of get you to understand what we're doing here what we're trying to create for every glucose molecule we're using particular molecules nadh as a hydrogen ion acceptor or or as an ion acceptor uh two ADP molecules and phosphate groups to create ATP so for every glucose molecule by way of glycolysis we're producing two ATP molecules in the end we're giving off a couple of of molecules that will actually be important for us later and another process here of the metabolic pathway also we're giving off pyruvate down below as you can see we're going to be using those again to help us create even more ATP so the first part of the metabolic pathway for you to remember glycolysis glycolysis now those pyruvate molecules are going to move they're going to move from inside the cell in the in the cytosol of the cell to a specific organ within the cell the mitochondria in The Matrix of the mitochondria we have another process that's going to utilize some of the products that came from the glycolytic pathway this process called the Krebs cycle or the citric acid cycle which is another name that you'll hear for this is a chain of reactions okay that again is in The Matrix of the mitochondria and its job to take some of those byproducts like pyruvate and help create a little bit more ATP we're going to squeeze what we can out of these molecules here all right now the Krebs cycle as you can see from this image again another elaborate type of process here acetyl COA which is coming from a breakdown of pyruvate gets entered into this cycle and again a series of enzymes will help rearrange molecules rearrange bonds and in the process we make some ATP and you can see down here for every acetyl COA or component of pyruvate that we utilize we make another ATP molecule at the same time again we're giving off particular byproducts that we will probably be able to use later all right also here we're giving off CO2 and water we're giving off CO2 in water all right now again I'm not asking you to know all the enzymes involved here oral molecules I need you to have a picture in your head of what's actually happening though glycolysis here on the left were Co has finished we're taking those pyruvates we're using a couple of particular enzymes to rearrange it and break it down a little further to create acetyl COA which gets fed into the citric acid cycle since we started with two pyruvates coming from a single glucose molecule we're going to create two ATP molecules two ATP molecules again we are giving off some other components here and these other molecules we're going to use later in the final component of this metabolic pathway anybody got that well before we move to that final pathway I want to kind of look at the mitochondria here a little more detail mitochondria the mitochondria in this cartoonish image here is a rod shaped or oval shaped structure large fairly large and a cell can have not just one but many mitochondria depending on how uh how important energy is needed inside that cell you'll see in particular types of muscle skeletal muscle in particular you're going to have mitochondria everywhere everywhere because we utilize the ATP or we need that ATP you can see from the mitochondria it has two membranes it's a double membrane system it has an outer bilipid membrane and an inner bilipid membrane in between or I should say in the middle of of the uh the second layer this area is called The Matrix this is where we see the Krebs cycle doing its work the next part of the of the metabolic pathway though we're going to see actually utilizes one of the membranes let's let's show you that component of it now the final process of the metabolic pathway is the electron transport chain or you'll also hear oxidative phosphorylation these two names are trying to describe the process that the molecules are going through as they come through this electron transport means yes we're exchanging electrons between particular molecules and when we're doing that Exchange we can rearrange bonds so that to to our advantage to our advantage oxidative phosphorylation well we're burning oxygen in this process and we're adding phosphorus groups to particular molecules ADP when you add a phosphorus group to ADP it becomes a t t ATP so that's where the name comes from well this process utilizes a series of four protein complexes and these protein complexes you've probably heard about a little bit in in different Realms of your life these complexes again are involved in very specific types of of reduction reduction reactions creating a kind of a gradient a process a flow that will help create ATP this process doesn't look quite as elaborate of what as what we've seen with the glycolytic pathway and and the Krebs cycle but it is every bit as important probably far more important than than the other two all those byproducts that we have from the glycolytic pathway and the Krebs cycle we're going to start to utilize nadh and hydrogen ions fadh and and other molecules like it feed into this this process all of these protein complexes that you're looking at here in the electron transport chain are actually embedded in the inner membrane of the mitochondria as we take these particles here or these parts and re reshuffle them within this electron transport area we create ATP now this process of the metabolic pathway the electron transport oxidative phosphorylation chain it's very slow very very slow however it creates a lot of ATP a lot of ATP from these byproducts from our previous two components of the glycolytic pathway again this electron transport chain is part of that inner membrane of the mitochondria and literally these electrons and particular molecules are shuffled back and forth across this membrane using these proteins to create that ATP that we need now how much ATP well from a single glucose molecule coming and going through glycolysis and then stepping through the Krebs cycle utilizing those byproducts that came from those first two processes we can create 34 ATP 34 ATP not bad huh not bad in review glycolytic pathway Krebs cycle coming or the the conversion of pyruvate to acetylcholate going into the Krebs cycle and then the byproducts of that Krebs cycle uh and glycolytic pathway feeding over into oxidative phosphorylation allows us to create 34 ATP molecules glycolytic pathway incredibly fast Krebs cycle pretty quick as well however does not produce as much ATP as what you'll see from the the oxidative phosphorylation component it's creating far more than what you're seeing up here that should be important to you as we start to talk about different cells and different tissues you're going to see those cells will utilize this whole process here this whole metabolic pathway that may Focus or may push to utilize one part of it more than another a reference skeletal muscle earlier skeletal muscle likes to use oxidative phosphorylation or particular types of skeletal muscle like you use oxidative phosphorylation more than the glycolytic pathway while other types of skeletal muscle will prefer to use the glycolytic pathway more than the oxidative phosphorylation pathway so we'll get to that complication later in essence or overall we will have this process here in the middle that helps us create ATP glucose is not the only molecule though that we can utilize to create ATP however it is the far more efficient one proteins and triglycerides we can also try to break down there's some some benefit to some of that and some drawbacks to that and we'll address that when we get to particular tissues and talk about how they may be utilizing these other components to create ATP everybody got that we'll talk to you later