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Cell Biology

Learn the toughest concepts covered in Cell Biology with step-by-step video tutorials and practice problems by world-class tutors

11. Aerobic Respiration



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Okay everyone in this lesson, we are going to be going over the basic structure and the basic mechanisms of the mitochondria. Okay, so the mitochondria is probably the most famous organ l that has ever existed. Right. We all know it's the powerhouse of the cell. It's a very famous organ. L and I know you guys have gone over this before. We're just going to do some overview background information to refresh your memory. Okay, so remember that the mitochondria has some very distinctive structures and it is going to be a membrane bound organelles that not only has one membrane but has two membranes. So there are two membranes which means there's an outer and an inner membrane. There is a space between those membranes and then there's a space in the middle of the mitochondria itself. So the first membrane is going to be the outer membrane and the outer membrane is going to allow certain molecules to enter into the mitochondria. And that is because it's going to contain these poor in proteins and poor in proteins sound like what they do. They make pores in the outer membrane or they make channels and these channels allow molecules to flow into the mitochondria. And generally these molecules are going to be important molecules for the process of creating a teepee for oxidative phosphor relation. So these are going to be things like ions that are needed for the production of a T. P. Now if anything really, really large needs to get into the mitochondria like a big protein that was made for the mitochondria. That protein is going to have to have a special kind of code to get past the outer membrane, otherwise, smaller molecules can diffuse through the outer membrane. Or other molecules are going to have to travel through the poor in proteins which create channels. Okay, so we also have the inter membrane space. This is going to be the space between the outer membrane and the inner membrane. If you guys were wondering, there are actually two names for this space, of course it can be the inter membrane space. It can also be the perry mido Condra real space as well. Just in case you guys see that as well, they mean the same thing. Para mitochondrial space and inter membrane space is the space between the two membranes of the mitochondria. So this is of course that space in between. And this is going to be pretty chemically equivalent to the side is all meaning that it's pretty much just an acquittal solution in between these two membranes. There aren't a lot of proteins in this particular area. There is one major protein in this area called cytochrome c, which we will learn much more about whenever we learn about oxidative phosphor relation, but it's one of the only proteins that really exists in that area and it's utilized to transport electrons in the electron transport chain. Alright, so now let's move on to the inner membrane. This is probably one of the most important structures inside of a mitochondria because if you remember whenever we learned about the electron transport chain, this is where that particular thing lives. So very important characteristic to realize about the inner membrane is that unlike the outer membrane it is impermeable to ions and small molecules. This is very important. This mean that ions and small molecules cannot pass the inner membrane unless they have specialized transport proteins. And if you remember anything about the electron transport chain that is really important for the creation of the hydrogen ion gradient. Now this is going to be the membrane that's going to hold all the trans membrane proteins that are utilized in oxidative phosphor relation. So these are going to be the electron transport chain proteins. These are going to be those proteins that move hydrogen ions. And this is also going to include a T. P. Synthesis which creates A T. P. So this is a very important region because it is the site of oxidative phosphor relation or the creation of a T. P. Via the mechanisms that utilize oxygen. And this inner membrane is obviously very important for a T. P. Production. So we want to have a lot of surface area on that particular inner membrane. So this inner membrane is going to fold and it's going to fold in a way and these folds are going to be called Christie or chris day depending on how you want to say it. And so these folds in the inner membrane are going to be called Christie. And this is going to increase that surface area. So we have more area to have more electron transport chain proteins to generate more ATP Now finally the last region of the mitochondria we need to talk about is going to be the mitochondrial matrix. This is inside of the inner membrane, This is the innermost region of the mitochondria. And actually this is where the majority of the proteins are going to be found inside of the mitochondria. We don't generally talk much about the matrix but it is very very important. Just some background on the mitochondrial matrix. This is going to be where the mitochondrial D. N. A. Is going to be found. Yes, they do have their own D. N. A. This is where mitochondrial ribosomes are going to be found. They do have their own ribosomes as well. Many, many enzymes are going to be held here. And also this is where the citric acid cycle actually takes place. So this is a very important region of the mitochondria. So now that we went over the major point of the mitochondrial structure, let's have a look at just an overview of what a mitochondria is going to look like. So this is going to be the mitochondria. They're kind of like a bean or rice green shape and you can see all the different structures that we talked about. We have the outer membrane here which is going to be the brown area. Then we have the inner membrane space which you can see right here. Then we have the inner membrane which is going to be in yellow and then we are going to have the matrix here in blue. Now remember I told you the matrix is going to hold a lot of things. You can see here that the matrix is holding that mitochondrial D. N. A. And it's going to hold those ribosomes. And you can see there are 80 p synthesis particles synthesis proteins that are waiting to be utilized in the inner membrane. And then you can see for the inner membrane, the chris die those are those folds, you can see those folds in the inner membrane, that yellow line there. And then you can see these Granules. I didn't talk about these Granules but basically they're just little storage areas for things like important ions for the electron transport chain or other important molecules. They're just little storage areas. So that's going to be the overview of the mitochondria structure. So now let's go down and talk about some more unique character of the mitochondria. Okay, so they do have some pretty unique characteristics in the fact that they can remain in fixed locations or they can move throughout the cell depending on what the cell needs at that particular time. And the way that they move throughout the cell is going to be on micro tubules remember micro tubules are going to be a major avenue for transportation for things like vesicles organelles and mitochondria. Now, mitochondria you may not know this. They can actually fuse together or be spliced apart whenever they fuse together they create tubular networks. Now why would they want to fuse together? What would be the point fusing together allows them to exchange resources and this is going to make them more efficient because all of them have the same substances that they need to utilize to build a teepee. So they're basically just exchanging information, exchanging resources and forming these tubular networks. Now. Like I already talked about mitochondria are also very unique because they do have their own D. N. A. Genome. Just you guys know cooler plastic also have their own DNA genome. And this is because they are believed to be endosymbiont that they were once pro carriers that were engulfed by a larger cell and then they became an organ L. So because they were once precarious, they are going to still retain their D. N. A. And that's why it circular if you remember pro carry attic D. N. A. Is circular. And this D. N. A. Is going to encode for some polyp peptide some T. R. N. A. S. Some ribs. OMA RNA. To be utilized with the ribosomes and to build whatever proteins the mitochondria might need. Now they're going to create all of these proteins that they might need and hold all of this D. N. A. In the mitochondrial matrix. Like we talked about. All right. So now the like I said the middle country can make their own proteins. They have their own ribosomes. They have their own DNA. But it's important to realize that they're not self sufficient. They are going to have to have proteins made for them in other regions of the cell. They don't contain all of the genes and all of the information that they need to build all of their proteins. So they still do rely on the nucleus for a lot of genetic information but they can make some of their own proteins. But if they do need the cell to make them certain proteins they're going to have to import those cellular proteins through the outer membrane and through the inner membrane. So there's some special transportation that happens in that process. Now. Remember I talked about the ability of mitochondrial fusion then forming these tubular networks. Well this is going to be a visual representation of these tubular networks. And actually the mitochondria are the green little filaments you see there And that's really crazy to me whenever I look at this picture because that's just not what I think of. Whenever I think of mitochondria but they are actually all fused together. You can see these lines of mitochondria in these particular cells are all fused together. That's because they're exchanging resources and exchanging information and they're forming these long tubular structures to do a p a t. P synthesis. Okay, everyone that was the basic information and background on the mitochondria. Let's go on to our next topic.


Match the mitochondrial structure with the correct definition 

I. Outer membrane          _____________ 

II. Intermembrane space _____________ 

III. Inner membrane         _____________ 

IV. Cristae                         _____________ 

V. Matrix                            _____________ 

a. Space between the two membranes 

b. Internal space of the mitochondria 

c. Contains porin proteins which allow larger molecules to flow into 

d. Impermeable to ions and small molecules 

e. Infolds that increase the surface area of the membrane

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Which mitochondrial structure is the location of oxidative phosphorylation?


True or False:Mitochondria always exist as distinct organelles that never come together to form larger structures.