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 organelle that has ever existed, right? We all know it's the powerhouse of the cell. It's a very famous organelle, 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 organelle 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 porin proteins. And porin 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 ATP for oxidative phosphorylation. So these are going to be things like ions that are needed for the production of ATP. 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 pore and proteins which create channels. Okay. So, we also have the intermembrane 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 intermembrane space. It can also be the perimitochondrial space as well. Just in case you guys see that as well, they mean the same thing. Perimitochondrial space and intermembrane 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 cytosol, meaning that it's pretty much just an aqueous 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 phosphorylation. 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 a mitochondria. Because if you remember, whenever we learned about the electron transport chain, this is where that particular thing lives. So a 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 means that ions and small molecules cannot pass the inner membrane unless they have specialized 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 transmembrane proteins that are utilized in oxidative phosphorylation. 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 ATP synthase, which creates ATP. So this is a very important region because it is the site of oxidative phosphorylation or the creation of ATP via the mechanisms that utilize oxygen. And this inner membrane is obviously very important for ATP 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 cristae or cristae, depending on how you want to say it. And so these folds in the inner membrane are going to be called cristae. And this is going to increase that surface area, so we have more area to have more electron transport. The last part 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 the mitochondria. We don't generally talk much about the matrix, but it is very important. Just some background on the mitochondrial matrix. This is going to be where the mitochondrial DNA is going to be found. Yes, they do have their own DNA. 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 points of the mitochondrial structure, let's have a look at just an overview of what a mitochondria is going to look at look like. So this is going to be the mitochondria. They're kind of like a bean or rice grain 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 DNA, and it's going to hold those ribosomes. And you can see there are ATP synthase particles, ATP synthase proteins that are waiting to be utilized in the inner membrane. And then, you can see for the inner membrane the cristae, 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 characteristics of the mitochondria. Okay. So, they do have some pretty unique characteristics in 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 microtubules. Remember, microtubules 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 ATP. 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 DNA genome. Just so you guys know, chloroplasts also have their own DNA genome. And this is because they are believed to be endosymbionts, that they were once prokaryotes that were engulfed by a larger cell, and then they became an organelle. So because they were once prokaryotes, they are going to still retain their DNA. And that's why it's circular. If you remember, prokaryotic DNA is circular. And this DNA is going to encode for some polypeptides, some tRNAs, some ribosomal RNAs 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 DNA in the mitochondrial matrix, like we talked about. Alright, so now, like I said, the mitochondria 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 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 ATP synthesis. Okay, everyone. That was the basic information and background on the mitochondria. Let's go on to our next topic.
Mitochondria: Study with Video Lessons, Practice Problems & Examples
Created using AIThe mitochondria, known as the powerhouse of the cell, feature a double membrane structure comprising an outer membrane with porin proteins for molecule entry, and an inner membrane that is impermeable to ions and small molecules. The intermembrane space, or peri-mitochondrial space, is chemically similar to the cytosol. The inner membrane houses the electron transport chain and ATP synthase, crucial for oxidative phosphorylation. The mitochondrial matrix contains its own DNA and ribosomes, facilitating protein synthesis and the citric acid cycle. Mitochondria can fuse to exchange resources, enhancing ATP production efficiency.
Mitochondria
Video transcript
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
Problem Transcript
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.
Here’s what students ask on this topic:
What is the structure of the mitochondria and its functions?
The mitochondria have a double membrane structure. The outer membrane contains porin proteins that form channels for molecule entry. The intermembrane space, or peri-mitochondrial space, lies between the outer and inner membranes and is chemically similar to the cytosol. The inner membrane is impermeable to ions and small molecules and houses the electron transport chain and ATP synthase, essential for oxidative phosphorylation. The mitochondrial matrix contains mitochondrial DNA, ribosomes, and enzymes for the citric acid cycle. Mitochondria can also fuse to form tubular networks, enhancing ATP production efficiency by exchanging resources.
Created using AIHow does the electron transport chain function in the mitochondria?
The electron transport chain (ETC) is located in the inner membrane of the mitochondria. It consists of a series of protein complexes that transfer electrons from electron donors to electron acceptors via redox reactions. This process creates a proton gradient across the inner membrane by pumping hydrogen ions (H+) into the intermembrane space. The resulting electrochemical gradient drives ATP synthesis as protons flow back into the mitochondrial matrix through ATP synthase. This process, known as oxidative phosphorylation, is crucial for ATP production.
Created using AIWhat is the role of the mitochondrial matrix?
The mitochondrial matrix is the innermost compartment of the mitochondria, enclosed by the inner membrane. It contains mitochondrial DNA, ribosomes, and a variety of enzymes. The matrix is the site of the citric acid cycle (Krebs cycle), where acetyl-CoA is oxidized to produce NADH and FADH2, which are then used in the electron transport chain. The matrix also plays a role in the synthesis of some mitochondrial proteins, thanks to its own DNA and ribosomes.
Created using AIWhy do mitochondria have their own DNA?
Mitochondria have their own DNA because they are believed to have originated from free-living prokaryotes that were engulfed by a larger cell in a symbiotic relationship, a theory known as endosymbiosis. This DNA is circular, similar to bacterial DNA, and encodes for some of the proteins and RNAs needed for mitochondrial function. Although mitochondria can produce some of their own proteins, they still rely on nuclear DNA for many essential proteins.
Created using AIHow do mitochondria move within the cell?
Mitochondria move within the cell using the cytoskeleton, specifically microtubules. Motor proteins, such as kinesin and dynein, transport mitochondria along these microtubules to different locations within the cell. This movement is essential for distributing mitochondria to areas of high energy demand and for cellular processes like mitosis and apoptosis.
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