hi everybody it's your ap bio teacher mr poser we are continuing our second unit on cell structure and function with topic two cell structure and function today what we were talking about is a a little more detail into the structure of some particular organelles and how that serves their function so one of the major themes in all of biologies that form meets function and each subcellular component of the cell structure contributes to serving its function so this is pretty common among every single biological topic that there is um things are formed in such a way that helps them accomplish their function um and that's something that we're going to be looking at in today in more detail with regards to two particular organelles or subcellular components but just as a recap here there's a few things i want to point point out that we talked about in our last video in 2.1 lysosomes what their job is if you don't remember is to digest and break down macromolecules that could serve as waste or they could serve or you know just for hydrolysis of larger uh components and it also helps in cell or programmed cell death called apoptosis so it helps digest those things um and the lysosome is built in such a way that it is surrounded by a membrane that contains these enzymes it helps it do its job vacuoles are surrounded by a membrane and their job is to store molecules from waste products and particularly in plants water to provide that turtle pressure that we talked about in the last video and finally the er the endoplasmic reticulum it's a system of membranes and its smooth part and its rough part the fact that it's embedded with ribosomes particularly the rough part is formed in such a way that allows it to carry out its functions which includes synthesizing proteins through those ribosomes and labeling them as glycoproteins to move around within the cell building a vesicle for them and as well as lipids in the the smooth er and so that it can transport them and in addition because the endoplasmic reticulum can be so extensive it provides mechanical support for the cell so one of the main ideas of all bio as i'm pointing out here is that whatever something's function is its structure or its form allows that to allows that to serve its function all right so uh the two main organelles that we're going to get into today and the structure and function of each are the mitochondria and the chloroplast and the reason why we're getting into those tubes is because in our third unit uh we are discussing more extensively um the processes that go on within these cells or excuse me within these organelles because they're key components of metabolism so cellular respiration and photosynthesis we're going to talk about that a lot um so as we know mitochondria the polar host of the flow carries out metabolic reactions and most notably atp synthesis atp a cell cannot function without atp life cannot function without atp and different reactions different metabolic reactions take place in different compartments of the mitochondrion if you remember from the last video i believe i might have said this but a mitochondrion has a double membrane so it has an outer membrane and an inner membrane so if we take a look at this uh diagram here we have outer i kind of tried to color code it a little bit uh so the outer membrane is this kind of tan structure here um the inter membrane space it's darker brown it's in between the outer membrane and this yellow component which is the inner membrane and inside the inner membrane is what we call the mitochondrial matrix or just the matrix in this case and in the last thing i want to point out here is that this membrane this inner membrane is very convoluted it's got lots of fold and it's kind of smushed together within the mitochondrion and those folds are called christie christie i think krista no i i don't remember what the center the singular is but christy is the term for these folds in the inner mitochondrial membrane um and folds in a membrane provide for better surface area which is a topic that we'll get into into in the next topic uh which is 2.3 we'll talk about that quite a bit another thing to note for later on is that mitochondria have their own dna and they have their own ribosomes so their cellular origin is something that is explained by what we call endosymbiosis which is actually topic 2.11 so here's the couple things about how this mitochondrion is compartmentalized so aerobic cellular respiration occurs within the mitochondria so there's anaerobic respiration and there's aerobic respiration anaerobes like yeast and bacteria that don't have these mitochondria are not able to accomplish um all these other steps of making atp and cellular respiration again a topic that we're going to get into a lot it's basically the production of atp right um so there's three steps to it there's one that occurs outside of the mitochondrion that the bacteria and yeast and other single-celled organisms prokaryotes are able to do and that's called ferment or it's called glycolysis i should say but these other two steps along with atp synthesis occur within the mitochondrion so it's not this step after the um glycolysis which occurs outside of the mitochondrion occurs within the matrix and it's called the krebs or the citric acid cycle and the citric acid cycle once that produces the the products that it needs to um start it powers what we call the electron transport chain and it's also known as oxidative phosphorylation i mean that occurs along the inter the inner membrane excuse me the inner membrane of the mitochondrion all right so there are proteins that line along this membrane here and a lot line along the christie they're called cytochromes and what they're able to do is pass an electron from one place to an x to the next and allow for atp synthesis to occur so this is actually where your body is able to produce atp is along the inner membrane of the mitochondrion all right so let's keep going here the other main organelle that we're going to be talking about is the chloroplast and they have a lot in common with mitochondrion chloroplasts also have inner membrane systems so they have a double membrane much like the mitochondrion and they also have different sets of reactions that take in parts in different places within that organelle leading once again to the idea that you know chloroplasts and mitochondrion used to be their own organisms so that has to do with the evolution of eukaryotes but yeah a few things that they have in common let's take a look at this diagram that i made of uh of the chloroplasts um so once again we have an outer membrane so this darker green i couldn't really i couldn't really color code it this time since it's all like the same color uh the inner membrane sits right below it okay there's no folds in that inner membrane uh like in the mitochondrion but what's important to note are these other three structures within the inner membrane uh you have stat these kind of like poker chip shaped uh structures they're called thylakoids thylakoids over here um and a stack of these thylakoids is what we call a granum so there's uh the chloroplast has multiple grana which are these stacks of thylakoids within its uh within the inner membrane and the fluid outside of the grana but within the inner membrane it is called the stroma it's kind of like this fluid jelly like substance and it contains particular compounds that allow the chloroplast to do its photosynthesis job all right so thylakoids gronin and stroma are going to be pretty important um and here's why when we get into photosynthesis in our third unit we're going to be talking about the light dependent reactions of photosynthesis the ones that must be done in the presence of some kind of some kind of light energy um those occur within the grana okay so those all happen along the uh thylakoid membranes and the thylakoid membranes contain you may have heard of this compound chlorophyll chlorophyll is for the light absorbing pigment it's you know it reflects green light that's why it's green um and the what we call the photosystem protein so again when we get into this in unit 3 we're going to talk about photo system 1 and photo system 2 and the roles that they play um in producing um nadph which is going to we'll talk about it later okay uh but the light dependent reactions what you need to know today is that those reactions that occur within light or with light happen in these thylakoids and along these grana but the what we call dark reactions or what we call the light independent reactions that take carbon dioxide in the products from the light dependent reactions and are able to produce those six carbon glucose molecules that's called the calvin cycle that occurs within the stroma so that's still within the inner membrane of the chloroplast but it's outside the thylakoids and outside the granule okay so light dependence and the thylakoid membranes and the dark reactions occur within the stroma outside of the thylakoids okay um that'll be it for this video in the next video we're going to get into cell size and why that matters and do a little math don't you love math all right we'll see you next time let me know if you have any questions