Endosymbiotic Theory

in this video, we're gonna do a quick recap on the Endo Symbiotic theory, so recalled at the end of symbiotic theory explains the development of complex eukaryotic organisms such as ourselves. And it suggests that mitochondria and chloroplasts organelles were once independently living bacteria. And it also suggests that about 1.5 billion years ago, there was an aerobic bacteria or a bacteria that uses oxygen in its metabolism that was engulfed by an anaerobic host cell or hotel that does not use oxygen in its metabolism. And that created a symbiotic relationship. Were both organisms benefited, and so the Arabic bacterium was provided protection by the host cell, and the host cell was provided an Arabic metabolism by the bacterium. And over time, this Arabic bacterium would have lost many of its genes and abilities, including the ability to survive on its own. And it would have developed into today's mitochondria. And so in a similar fashion, a photosynthetic cyanobacteria would have also been engulfed by a host cell, and over time it would have evolved into today's chloroplasts. And so let's take a look at our example below and notice on the far left. We have our host cell, which again is anaerobic and does not use oxygen and notice that our host cell already has a nucleus. And so that means it's already a eukaryotic cell. And the end of symbiotic theory does not suggest the creation of a eukaryotic cell. It suggests the development of a eukaryotic cell, and so this anaerobic host cell would have engulfed an Arabic bacterium, and this Arabic bacterium would have developed into today's mitochondria and again in a similar fashion, the cyanobacteria would have been engulfed and developed into the chloroplast and host cells that had both organ Al's would have developed into plant cells and into today's plants. Now host cells that Onley, uh, engulfed the Arabic bacterium would have on Lee had mitochondria, and so these host cells would have developed into today's animal cells and in tow. Animals such as this Rafiki looking monkey appear with some yellow teeth. And so, uh, there's lots of supporting evidence to support this theory, and most of it has to do with the fact that mitochondria and chloroplasts resemble pro carry outs. And so mitochondria and chloroplasts both have small circular DNA, just like pro carry outs. They have 70 s ribosomes, just like procure yachts. And they replicate via binary fission, just like pro carry outs. And mitochondria and chloroplasts also have, uh, a double membrane and the double membrane. The membranes differ from one another, so the outside membrane more so resembles a eukaryotic cell in the inside membrane. More so resembles a pro carry attic cell, and that's suggestive of being engulfed. And so, in our next video, we're gonna do a quick recap on the mitochondria, so I'll see you guys in that video.

so the mitochondria and the processes that occur inside of it are a major focus of biochemistry, and later in our course we're going to talk a lot of details about the mitochondria and all of those processes. But in this video, we're just gonna do a quick review. So that being said, recall that the primary function of the mitochondria is to produce a teepee or the high energy molecule for herself. And the bulk of this 80 p is produced via oxidative energy metabolism or reactions that require the presence of oxygen. Now most textbooks tend to show the shape of the mitochondria as a bean shape, such as this one here. But what most people don't realize is that the mitochondrial shape varies greatly from Salva Cell. Also, a separate fact to remember from our previous videos is that mitochondria have their own small circular DNA that is separate and independent from the nuclear DNA. Also, mitochondria have a double membrane, so they have an outer as well as an inner membrane, and the inner membrane is highly folded into structures called Chris Stay that increase the surface area and lead to more energy production. Also, mitochondria are the location of major processes of cellular respiration, which include the citric acid cycle and the electron transport chain. So down below, in our example, is a chemical reaction that's probably burned into your guys brains by now by how many times you've seen it in your previous bio courses. And that's the overall chemical reaction of cellular respiration. So on the reacted side, we have glucose as well as oxygen, gas and cellular respiration. Converts these reactant into the products of carbon dioxide, water and energy in the form of a teepee, and so to review the typical structure of the mitochondria recall that it has a double membrane, so it has an outer membrane that goes around the perimeter, and then it also has an inner membrane that's interior to that, and that's highly folded into structures called Christie. And so in between the inner and the outer membrane is a space, and the space is called the inter membrane space and recall that this is very important to the electron transport chain processes. Now the most interior area of the mitochondria is referred to as the mitochondrial matrix, and this is the location of the citric acid cycle. Now there's an enzyme that's known as the A T. P synthesis, and this is the enzyme that produces the bulk of the 80 p that's associated with the mitochondria. And really, they're the main reason that mitochondria are associated with a teepee. And so, from our previous videos, we talked about how mitochondria have their own ribosomes. And these are 70 s ribosomes, which are pro carry attic ribosomes. And they also have their own DNA, which are small circular DNA, just like the DNA of pro carry. It's. And they have multiple copies of that DNA, if you notice, which tends to be very common. And so again, we're gonna talk a lot. Maura, about mitochondria and cellular respiration later in our course. But for now, this is a good summary as we move forward. And so in our next video, we're gonna talk about the chloroplast, so I'll see you guys in that video

in this video, we're gonna brush up on the chloroplast and recall that the primary function of the chloroplast is to perform photosynthesis. And you guys have learned in your previous bio courses that photosynthesis produces chemical energy from solar energy. And so let's take a look at our example below. And so we've got the sun here that's providing solar energy, and we also have a plant that's absorbing that solar energy and recall that plants have chloroplasts organelles and the chloroplasts organelles perform photosynthesis for the plant and so down below. We have the overall chemical reaction for photosynthesis, where on the react inside we have carbon dioxide water as well as sunlight and photosynthesis, converts these three react INTs into glucose as well as oxygen gas. And so this glucose here is what we're referring to as chemical energy. And so to review the structure of the chloroplast. Recall that it has a double membrane, so it has an outer membrane on the perimeter and an inner membrane that's interior to that. And so the Strom A here is referring to the fluid filled space that fills the internal portion of the chloroplast and so notice that Within this Troma lies thes green pancake looking structures that air individually called Fila Coy AIDS and so notice these Thilo Coid are stacked on top of each other. And so this particular stack has five Thilo, Coy's and each of the stacks of dilla. Coy's is called a grain, Um, and so there are a bunch of grana in this Troma and so recall that photosynthesis consists of two major processes and multiple reactions, and those reactions take place in different parts of the of the chloroplast. Some take place within the Thilo Coid membranes and others take place within this Troma, and we'll talk more details about photosynthesis later in our course. But for now, this is a good summary, and I'll see you guys in the practice problem videos.