Hey guys, welcome back to Biology. This is podcast number 6.1 and this is part of the photosynthesis and respiration unit. So today we're going to take a look at the structure of the chloroplast. And if we remember from our cells chapter, the chloroplasts are found only in plant cells. This is one of the organelles that is only in plants, the cell wall being the other one that's only in plants. But today we're going to focus on this guy called the chloroplast. There's a few different parts that we need to make mention of. And the first part of that is that this has an outer membrane or an outside membrane as well as an inner membrane. It's a double layer. So it's got an inner membrane. So this is a double layer of membrane, that lipid membrane that goes around the outside of this. Because we move inside of the cell, or I'm sorry not if the cell of the chloroplasts, as we move into the chloroplasts, I'm going to change my color to blue, there's some empty space around these stacks that we see here. And this is called the stroma. That liquid that surrounds everything is called the stroma. And it flows around through this inner membrane. These guys here in the middle, we're going to look at a single one. I'm going to use green for this. A single one of these ovals here in the middle. This is called a thylacoid, THYLAKID. And I did this in green because this holds the chlorophyll. Okay, so this is where the chlorophyll is in the chloroplast itself. The chloroplast again. It's a membrane bound organelle. And the chlorophyll within that is held specifically within one of these thylacoids. Okay, so each of these single stacks here, or each of these single ovals holds just a bag of chlorophyll. And then the last piece we need to look at, we'll do in red. If you notice that these are stacked with one another. So we're going to look at an entire stack of thylacoids. And this is called a granum. And this is a stack of thylacoid. So a single thylacoid holds the chlorophyll. A stack of thylacoids is called a granum. And then the stroma flows around that and they are both held within the membrane. Okay, then down here at the bottom of your notes, the chloroplast again, it contains the chlorophyll. And the chlorophyll, that is what is absorbing the light that the plant needs to carry out this process of photosynthesis. So the light comes in, I don't know if I do have yellow, it might be hard to see, but the light comes in from the sun, hits one of the thylacoid and that will begin the photosynthesis process. And there's two steps to that, but we're not going to worry about that too much. So that's basically it. It's a very basic structure of a chloroplast. If you have questions, we'll be talking about it in class more.