Mitochondria, also called mitochondrion, are organelles found in eukaryotic cells in which aerobic cellular respiration takes place. Mitochondria generate ATP which cells use for energy and have both an outer and inner membrane. The space between two mitochondria is called the christa, while the space inside the inner membrane is called the matrix.
Most students will have heard of the mitochondria and they say it's the power house of the cell but they don't really know what that means. Mitochondria is the organelle that does what's called aerobic respiration which is the breakdown of food using oxygen and what that allows the cell to do is to get a bucket at load of ATP the Energy molecule of the cell for every glucose molecule or even other kinds of food molecules that come into the cell.
Now one of the things that's unusual about the mitochondria is its one of the organelles that develop through a process called endosymbiosis, and I'll address that in just a little bit. But because of this it is one of the key organelles that if you see it you know you're looking at a eukaryotic cell.
Let's take a look at a cell diagram over here and here we can see again the cell membrane nucleus right over here is the mitochondrian, if you're ever looking for the mitochondria just look for the thing that looks kind like a bean with a bunch of wiggly bits on the inside. If we take a closer look here's the outer membrane of the organelle the mitochondria and then there's the inner membrane of the organelle. The folded inner membrane is called the cristae and that's one of the key things that key structures that you'll see in a mitochondria. Now I mentioned earlier that it's endosymbiotic. What does that mean? That means that this organelle like the chloroplast and the nucleus came about when one large cell ate some smaller cell and what's some of the evidence we'll take a look. We have one membrane on the outside from the larger cell wrapping the inner membrane came from that original cell, not only that but if you take a look these little red circles those are some of the mitochondrial DNA which is circular just like the circular DNA of bacteria and in fact floating around in this liquid here which is called the matrix, you find these little ribosomes which are different from the ribosomes of the other cell they're just like the ribosomes though of bacteria of prokaryotes.
And so again to just summarize, mitochondria is the power house of the cell it does aerobic respiration the breakdown of glucose using oxygen and it is one of the three major endosymbiotic organelles; the nucleus, chloroplast and mitochondria.