in this video we'll be talking about sales structures and processes it's part of a 2.2 on sales structure and this is part of the standard level or core content so the theme of this whole unit is unity and diversity so it's important to keep an eye on those big thematic pictures right so we know that living things are very diverse they're very different but there are some things that they have in common that really plays this Unity theme so all cells are going to have a plasma membrane that's going to go around the outside um we'll talk lots more about that another time but it's a semi-permeable uh layer made out of phospholipids all cells are going to include cytoplasm it's a watery based solution um where all of the metabolic reactions are going to occur and all organisms have DNA as their genetic material now some of you will end up studying viruses later on viruses can sometimes use RNA as their genetic material but it's important to note that viruses are not considered to be living things um there's some functions of life that they can't perform so we can safely say that all living organisms use DNA as their genetic material organisms can be classified in lots of different ways but all cells are going to fall into two basic categories they are either procaryotic cells which we will talk about right now or eukaryotic cells which we will talk about in just a moment this picture is a procaryotic cell procaryotes I often um think about as bacteria so we'll kind of go into that in just a bit but procaryotes in general are much simpler in their structure they are smaller they're generally less than 10 micrometers and they Evolved first they were the first types of cells to evolve they're also ubiquitous which means that they are found in every different biome and habitat um on Earth procaryotes in their General structure are going to lack a nucleus so they're not going to have their DNA surrounded by a membrane they do have DNA it's just not surrounded by a nuclear membrane all procaryotes have a cell wall on the outside it's made of different things but they do have a cell wall and they are what we call non-compartmentalized that means that they are going to lack some of the organel or cell structures that we will find in eukaryotic cells now we will see these little dots here um these dots are um structures that help to synthesize proteins and those are ribosomes in procaryotes those are specifically referred to 70s ribosomes s is a unit of size okay so um we'll kind of expand upon that in just a moment but they have a particular size to their ribosomes and procaryotes um are uniquely 7s and their DNA which we mentioned here is not enclosed in a nucleus is sometimes referred to as naked DNA I don't love that term um that just means that DNA in procaryotes is not associated with what we call histone proteins so in ukar DNA is wrapped around little sets of proteins called histone proteins and they help do a lot of different things okay but in procaryotes they don't have histone proteins okay so we won't find that structure they just have the naked DNA and here in this diagram of a eukaryotic cell it's much easier to see now what we mean by this term compartmentalized so compartmentalized means we're going to have membranebound organel and they're going to be separated from the rest of the environment um of the cell and so in their tiny compartment they're doing a specialized job some eukaryotic cells like plants or fungi have a cell wall but not all of them like procaryotes all have a cell wall and ukar only some of them there are some things that ukar have that are lacking in procaryotes one of the main features is their nucleus so this is the nucleus of this eukaryotic cell and inside of the nucleus we would expect to find all of that organism's DNA the nucleus itself is a double membrane and it's got small holes called pores we'll talk more about the nucleus in a minute um but that uh nuclear membrane is very characteristic of ukar notes inside of the nucleus is the the DNA sometimes it's in the form of chromosomes um and that DNA is associated with his Stone proteins so in UK carots that DNA is going to be wrapped around things called histone proteins and again we don't find those in procaryotic cells in UK carots we're also going to find ribosomes but they are not 70s ribosomes like in procaryotes they have a different size these are 80s ribosomes they're a bit larger and all ukar are going to have mitochondria so I see a mitochondria here some ukar will also have some other structures like a chloroplast or maybe an endoplasmic reticulum but not all of them so it's important to note what is characteristic to all all ukar and for that we want to be thinking mitochondria theme a is all about unity and diversity and we've talked a lot about how cells are different but there are ways in which they are the same and so there are certain processes of life that are going to be common to all organisms and this is a new unicellular organisms that just means that that one cell has to do all these things but multicellular organisms do these as well and I like to remember the pneumonic Mr Shang because it helps me to remember them all right so the first one here is metabolism metabolism is all of the enzyme catalyzed reactions in the cell now that's closely related to nutrition nutrition is getting the nutrients required metabolism is doing stuff with those nutrients and excretion is the removal of waste products left over from that metabolic process so those are kind of related um all living things are going to grow that means increasing in either size if you're multicellular or unicellular like so increasing in that size of that one cell or adding on new cells if you're multicellular so all of the things are going to grow and they're going to reproduce whether that's sexually or asexually that can look very different but production of Offspring is also common to all living things now all living things must um maintain homeostasis and homeostasis is a living organism's ability to regulate the inside conditions to keep them stable and within narrow limits regardless of what's happening in the outside environment and that has to do with sensitivity right so living things are going to be able to react to stimuli in their environment with various responses so some of those responses are going to be internal in order to help maintain homeostasis some of them will be external it doesn't necessarily mean moving it can mean lots of different things but again these are what we want to think of that all living things have in common um what makes Unity amongst the various life forms in unicellular organisms those are organisms made up of only one cell um that one cell has to do all of those different functions and we'll talk about that in just a moment in multicellular organ organisms that's you and me we're made up of many cells we have different cells to carry out different functions so those cells start to specialize and some cells might be really good at responding other cells might be much better at homeostasis so different cells to perform different functions of life now in unicellular organisms I need to be looking for parts within that single cell that can do all of those functions and parium and camonis are great examples of this so let's talk about this parium first I see these tiny little hairlike projections on the outside these are called cyia and they are there for movement so a great way for this cell to maybe respond to a stimulus in its environment and either move towards or away from something I'm seeing these crazy starshaped uh bits here these are something called a contractile vacu contractile vacul are going to help that organism remove excess water and that's a great example of Performing homeostasis I'm also going to see tiny little food vaces so a food vacu is uh an enclosure that is going to kind of hold food that that organism has ingested what else are we seeing here I'm also seeing cytoplasm so the cytoplasm is going to be that watery based substance where all the metabolic reactions can occur and I see a nucleus so the nucleus is right here and of course the nucleus is going to um house all of that DNA which would be necessary for reproduction when this cell is ready to reproduce so again lots of different Fe fees um performing all of those functions of life camonis is a little bit of a different organism but it still has features to help it accomplish all of those functions these whip-like projections these are called flagella and just like the Celia they are also there for movement um this clonus also has a nucleus it's right here and it has a really big chloro plast so the chloroplast is this um like cup shaped green thing here and this is going to help this organism with its nutrition so whereas the parami is ingesting food the camonis is manufacturing its own carbohydrates through photosynthesis I'm also going to see a contractile vacu here which again helps this organism maintain homeostasis and proper solute levels and it's also going to have this really cool eye spot okay these are really if you look at these underneath the microscope you'll be able to see these and this eye spot is going to help this organism sense light and then move towards that light so that it can maximize its photosynthesis opportunities um so again a different structure um helping it to respond to that environment so let's synthesize some of of this information right unity and diversity how are things different how are they the same um when we think about plastids plastids are going to be things like a chloroplast so that's one example I'm going to find those in Plants only so I won't find them in fungi and I won't find them in animals cell walls are features that are common to fungi and plants but animals do not have a cell wall now this cell walls of fungi and plants are made of different materials but the structure does exist in both of them we will also find a structure called a vacu in both plants and fungi in animal cells these are either teeny tiny or they are absent so I typically don't associate uh vacu with animal cells centrioles on the other hand are present present in animal cells we'll talk about those later on in this section but centrioles are going to help move things around during cell division and we don't see those in fungi or plants so if you're looking at a micrograph and you see cental should be thinking animal cells all right this unul podia um what is that so I like to focus in on this word pod or pod it means foot so these are things that are going to help with movement so these are things like the cyia or the flagella and we looked at those in both that parium and the camonis but here we're not talking about unicellular organisms animals plants and fungi are mostly going to be uh multicellular okay um and I want to be associating those with animal cells so we won't find any of those um you know movement type structures on fungi or plants now unlike physics or chemistry and biology when we have a rule there's always an exception so remember back when we were talking about the cell theory we said that part of that was um a statement that says all organisms are made of one or more cells cells are supposed to be units that are clearly separated and have one nucleus and that's the case for most cells in most organisms but there are some exceptions that you should know so we need to know both the exception and why it is an exception so red blood cells in humans um you've probably seen those before they look like normal cells but they don't have a nucleus so there's no nucleus in those cells there's actually no DNA in those cells in Plants we're going to have something called a Flom SE tube element so it's part of the flum part of the transport mechanism for plants and those cells are are kind of sitting there but all of their cytoplasm and their nucleus has been removed they rely on neighboring cells called companion cells to help them do all the things so that's a weird one skeletal muscle it looks like this um skeletal muscle is made up of very long cells and these cells are what we call multinucleated so a single cell is going to have many nuclei so there's our ex exception for having one nucleus and the last one is really fun so these are called aseptate fungi so your septum okay is like this part here on your nose it means to separate a septate would mean no separation so instead of having clearly defined cells that are separated from their neighbor these cells lack a division they lack a cell wall okay and so again a great uh illustration of an example um that is an exception to the cell theory one of the more difficult tasks we have as biology students is to look at these pictures these are called micrographs and they come from electron microscopes and we have to know what it is that we are looking at and often we're asked to identify what type of cell is in this micrograph so there are a couple of tips that I can give you for figuring out what type of cell it is that we're looking at this is a procaryotic cell there are a couple of things that tell me that this is a procaryotic cell one of which is its shape most procaryotes are going to be either a rod shape a round shape or a spiral shape so in this case I'm looking at the billus or Rod shape of a bacteria the other thing that I would want to look at is the size so there's no size on this micrograph but in general um these are going to be less than 10 micrometers so they're kind of small now if we can't see a size what are some other things that we can point out well I want to look for this DNA all right so this is kind of hard to see if I do it in black but here's the DNA I'll redraw that maybe in yellow this darkened area in here this is all of that DNA and you can see it's just kind kind of like hanging out here in the middle it's not enclosed in that more rounded nucleus structure I can also see some ribosomes now that's not terribly helpful on its own because um other types of cells have ribosomes so we'll just kind of leave that be it's more about what I'm not seeing I don't see any of those membrane bound organel okay I don't see any evidence of compartmentalization and this is telling me that I'm looking at a procaryotic cell next let's look at plant cells and I'll tell you what is not going to be the case you won't get a picture of a green plant cell so again electron micrographs are in black and white um unless they are falsely colored or put through some of those fluorescent dyes so we can't rely on color um I want to be looking for a couple of things here with these plant cells so the first thing that I kind of notice when I'm looking at this plant cell is it has more of a geometrical shape to it um it's not a blob it's like a rigid shape and that is due to the presence of this cell wall so that's a great kind of visual cue the biggest thing I tend to look for is this structure right in here it's called the large Central vacu the Central vacu stores mainly water and plants tend to blow this up with water to pressurize their cells for support so on a microscope or in a micrograph it's going to take up a large portion of the cell look for that vacu um another feature that I would want to look for is the chloroplast so chloroplast are going to be kind of like bigger structures we'll look at those in more detail soon but I should also notice in these chloroplast maybe some darkened discs or spots those are dead giveaways that I'm looking at a chloroplast and if I'm looking at a chloroplast it's a plant cell um another thing that's good to find although it's not necessarily a distinguishing feature is the nucleus so the nucleus is right here it's usually kind of like rounded in shape it's filled with this like uh genetic material so so genetic materials tends to show up a little bit darker um and then I also usually see a spot in here called the nucleolus but this is a really typical picture of a nucleus like I said we won't find that in procaryotes um so that's helpful but we will find it in animal cells so um just have that in mind same thing here with the mitochondria again if I had to decide what I'm looking for in terms of a plant cell I want to be looking for three things I want to look for the shape I want to look for this large Central vacle and I want to try to look out for chloroplasts animal cells are a little bit tougher so they're not going to have a cell wall okay so their shape is going to be maybe a little bit more of a Blobby type shape but we have to be careful about saying that because I'm also going to have some animal cells that look like this and I'm also going to have some animal cells that look like long skinny crazy things okay so relying on a rounded shape is not a great idea but at least thinking about the absence of the cell wall and so it won't be just a rigid geometric shape um other things I won't see I'm not going to see a large Central vacu I'm not going to see chloroplasts I should be able to again find this nucleus okay um and that tells me that it's a eukaryotic cell from then on out what I'm doing to identify this as an animal cell is I'm eliminating it as possibly being a plant cell no uh vacu no chloroplast so hopefully that helps you identify some of these cells in micrographs