Hi in this video we are going to be talking about properties of the cell. So there are nine properties of the cell that I'm gonna be talking about. And I just want you to bear with me because they're not really connected in any way other than the fact that they're just all properties of the cell. And so you just kind of have to know what all nine are. And so I'm going to go over each one individually. So the first one is that sales evolved and they changed the circumstances over time. So before there were any sales present on earth, there was this chemical soup. And eventually this chemical soup um sort of resulted in the spontaneous formation of organic chemicals which contain carbon. And these organic molecules over time became more and more complex. But eventually a single cell was formed and we termed this the ancestral cell and it was formed around three billion years ago. Now eventually this ancestral cell evolved and adapted to become all of life's diversity present on earth today. Which is kind of a huge feet, huge undertaking. And so because there's so much diversity, we can actually classify organisms. And so how we classify them is by three domains called archaea bacteria. And you Kariya now archaea and bacteria. We sometimes just refer to them as one category, which we call pro carry oats. And then in you carry a we just term you carry outs, you'll see these terms a lot and you're probably familiar with them anyways an anti bio class. Now, how do we tell the difference between these organisms? Well we mainly do this through actually DNA sequencing. Um And that is looking at the genes and say okay well this gene is different from this organism and that allows us to tell the difference between the different domains especially the domains of Archaea and bacteria. Because they all just sort of look like single cell organisms and some of them do have different physical characteristics. But for the most part I can't really tell them apart just through looking at them. Um And so we use their D. N. A. Sequence to tell them apart. Now this diversity came about from the single ancestral cell because mutations or changes in the D. N. A. Sequence drove this evolution. So if we look at the three domains of living organisms we can see there's bacteria there's Arcadia and there's you Correo to they all came from the single ancestral cell just here located in this black line. But I think one of the interesting things about this which you don't necessarily need to know you don't need to memorize. But I think it's interesting is the fact that each one of these branches actually resulted in an entirely different domain. So we have you know one organism here we have another organism here and this organism eventually became this entire bacterial domain and this one eventually came the entire eukaryotic domain. And I think that's incredible to think about a single cell becoming this entire domain of organism through evolution. So now we talk about evolution, let's now turn to the next topic.

Hi in this video we're gonna be talking about the second property of cells. Which is that cells are organized complex and varied in their science or their size and appearance. So one common feature of all cells is that they have a plasma membrane which if you remember back to your bio intro bio class, these are made up of hydra filic and hydrophobic components. And these components just are named that way based on how they interact with water and these components because of how they interact with water eventually form a structure called a bi layer which we're going to discuss these terms and a lot more in later things. But this is just sort of refresher back to intro bio. Now differences in the internal structure of cells exist between pro carry oats and eukaryotes. So you may remember from your intro bio class that eukaryotic cells contain organelles um and a nuclear envelope in which D. N. A. Is separated from the other cell components. And so this provides really complexity um to the different types of cells that are present on earth. Because the you carry outs have all of these different compartments and they can do different reactions in them where the pro carry outs are more limited because they lack these compartments. Now, one of the things that is really common between eukaryotes and prokaryotes is that there's great diversity in size and appearance of cells. So for instance in this one bacteria lactobacillus, it could be around 25 micro meters. Where as a frog egg which is considered really a single cell is one millimeter which we can actually see with our eyes. It's a huge size range. And then also cell shape is extremely varied. So we think of a nerve cell and something like a giraffe neck. I mean that is an extremely long cell and they have single cells that traverse the entire neck. Um But then you also can have these sort of short squat cells like amoebas that project out and these are very different sizes. They're very different shapes and they have very different functions. So their cells are really varied. So if we look at just pro periodic cells you can see that just in the few organisms that are presented here extreme diversity. You have these circular ones. You have these long ones. Now. It's not important that you remember all these names on these images. You can kind of just ignore them and just look at the shapes and just say, okay well in this handful of organisms that I'm showing you right now, there's extreme diversity. So you can imagine the diversity that's present in the organisms that I'm not showing you right now. So in this topic we discussed that cells are complex and varied in their size and appearance. So let's now turn to the next concept

Hi in this video we are going to be talking about the third property of sales and that is that cells contain a genetic program and mechanisms to control gene expression. So I know that behind me there is a ton of text and I know that's overwhelming. But bear with me because the good news is is that you already know all of the information behind me. So you should have already gone through this with your intro bio class. And so I'm just going to be refreshing some of these terms for you so that we're all kind of on the same page before we get going. But you've all heard this, you've probably even heard it in high school. Um So these are concepts and terms that you know. So the first thing is that each cell has a collection of genes and they are encoded by D. N. A very basic. So D. N. A. Is made up of nucleotides which are made up of a deoxyribonucleic sugar, a phosphate group and a base A. T. C. G. And these are the building blocks of DNA. This is what DNA. Is composed of now D. N. A. The sum of all the DNA. In an organism is the genome And the genome can vary greatly. So for instance in very small organisms um the genome is only around 500 genes. Whereas in larger organisms like humans that can be up to thousands of genes. Humans have around 25,000 genes. So um but commonly between organisms they share around 60 genes every organism shares around that many. Now heredity is the mechanism of passing these genes on to your offspring. So the main form of gene expression and how cells control gene expression is through the central dogma of uh biology. And this is just D. N. A. Being transcribed to RNA and then being translated to protein. And I know that you've gone over this in your bio one on one class. You probably beat it to death and we're gonna beat it to that again and cell biology. But for now we're just reviewing it. So there's some RNA is that are really important in this process and include messenger RNA. And this is the difference in that in between other between D. N. A. Contains your cell instead of finding so you instead of a T. As a base. Now there's transfer RNA which is uh responsible for making the protein stringing together the amino acid that the protein is made up of. And this process occurs in the river zone which is made up of ribosomes while RNA. And then you have proteins. Which is the ending point here of the central dogma. And proteins are composed of amino acids arranging a polyp peptide chain. They can also act as enzymes which is just a fancy term that refers to proteins that catalyze or speed up chemical reactions now. So all of these terms you've heard of before. Just as a refresher. I wanted to mention them here. But one of the things that I think is really crucial and I think one of the ways in which cell biology is going to be different from your bio one class is that we're going to talk some more about gene expression control and how cells actually become different from each other. And so you can imagine that all cells in a multicellular organism. So humans for instance were made up of so many different types of cells but we all have the same genome, every single cell in our body has the same exact copy of jeans but they're all different. So how are they different and this are due to gene expression control. So we're gonna be talking a lot about that in the future but I just wanted to throw that out there is just sort of a cool thing to really be thinking about as we move forward in the cell biology class. Now, another thing that you may not have really thought about before or realize is that we always think of gene expression as DNA to RNA and then to protein. But sometimes protein isn't the final product. And instead DNA to RNA a can be a form of gene expression control. So gene expression can also occur through RNA molecules with activities that are like those of proteins. Now we're gonna talk about that concept a lot more in the future. But I just wanted to throw these concepts out there along with just a general refresher of intro bio so that we can just understand that a single property of all cells is that they contain this central dogma, that they contain genes that need to be expressed. Um and they have very similar mechanisms between all cells. So let's move on to the next concept.

Hi in this video we're gonna be talking about the fourth property of sales and that is that cells replicate in order to produce more of themselves. So DNA replication is the process of replicating the D. N. A. And it's the basis of all cell division. So how this happens and we'll go over this in a lot more detail later. But just the review is that each strand of the D. N. A. Is pulled apart and serves as a template during replication. So you can actually see this if I scroll down just a little, you have this D. N. A. And it's being pulled apart here and serving um for replication. Now, cell division occurs when two um when one cell produces two separate um cells. Now these cells can be genetically identical and that's in the case of mitosis or they can just be similar but not contain identical genes. Um And that is through mitosis which I didn't mention here but it's just a term that you will remember back from your bio one on one class. Um And these are two separate processes of cell division. Now you don't need to know the steps. I've sort of highlighted these three phases here. G. S. And M. Just wanted to mention that you know there's this circular process of cell division which you can see here in this image that composes of all of these different steps. Not necessarily important to know the exact terms or how mitosis works. You don't need to rush back to your bio 101 and read up all the chapters of my mitosis and mitosis. But we will be talking about it in the future in great detail and I just wanted to refresh you here. Um and so cells are considered the basic unit of living matter. And the reason that they are is because they divide. And so we all came from this original ancestral cell and it divided and that it still exists today and that all cells divide in order to produce more of themselves or in the case of mitosis, some daughter cells which are produced through asymmetric or genetically um non identical cell division. So now that we talked about cell division as a property of sales, let's move on to the next concept.

Hi in this video we're gonna be talking about the fifth property of sales. And that's that sales require and use energy. So every sale on earth needs energy to survive. But the source of that energy and how it obtains that energy can vary greatly between organisms. So there are these main classes of organisms that are defined by how they get their energy. So the first one is organa trophic and these are organisms that harvest energy from other living things. Photo trophic or organisms that harvest the energy of sunlight and lit a trophic organisms or harvest the energy of inorganic chemicals. Now there's another class of organisms that we can divide based on how they use oxygen. And so these are an aerobic and anaerobic organisms do not use oxygen. And aerobic um actually requires oxygen um in order to survive. And so cells use energy obtained in these different ways to form important macro molecules using a variety of cell functions. So you're going to be familiar with macro molecules from your intro class intro bio class and these are things like amino acids, nucleotides. Um and essentially um they require energy to form. And so the how much energy is required and how this actually happens is really controlled through the principles of free energy. And that explains the mechanisms of energy acquisition and usage. And we're going to talk about free energy a lot more in a future topic. But for now here are the four classes of macro molecules you're gonna be familiar with them, including carbohydrates, fatty acid amino acids. These are terms you should know from your intro class and I'm not I don't need you to remember these images or even remember the names. But what I want you to understand is that for amino acids to turn into proteins, you need energy for nucleotides to turn into DNA and RNA. You need energy. And so each one of these arrows represents an energy input that is necessary in order to be able to form these macro molecules that are crucial for our survival and for organism survival. Um so energy is really important property of cells. And so let's move on to our next concept.

Hi in this video we're talking about the sixth property of self and that is metabolism or the sum of all chemical reactions in a cell which is what metabolism is. And these chemical reactions and metabolism are crucial and essential for cells life. So one molecule that is the main energy storage molecule we're gonna be talking about a lot is a teepee or out of scene triphosphate. So this is the main energy storage. Let me spell right storage molecule that is crucial for cellular activities. And so we're gonna be talking a lot about a T. P. In the future. So I just wanted to remind you of it. You may be familiar with it from your intro class as well. Now there are some major metallic pathways that I know you're already familiar with. These are things like photosynthesis, oxidative respiration cli colle Asus which you've reviewed in your intro bio classes and these are networks of chemical reactions responsible for energy transfer in some way. So either energy usage or creating things in the cell that are necessary for its survival. And these pathways are really important. And we're gonna spend a lot of time talking on them in the future. But they are common across all cells. All cells do have some form of metabolism now um in metabolism. These are chemical reactions that are occurring. So there are special proteins that help chemical reactions occur and these are called enzymes and um or catalysts and essentially what they do is they speed up reactions by catalyzing them or um just allowing them to happen without as much input of energy. So eight ep helps out a lot with that. So I just wanted just to give you an idea of what a teepee actually looks like. It may be in a little while since you've seen it. So A T. P. Has the base, it has a ribose sugar and it has three phosphates, 123. And what happens when we're going to talk about this a lot more? So you don't necessarily need to know this now, but how it gives energy and how it's this energy storage is because it actually stores a ton of energy in these phosphate bonds. And you can see up here there's different classifications A T P A D P A M P. And this depends on how many phosphates it has left, so how left? So how much energy it has. So this is triphosphate, this is di phosphate and this is mono, So this is 32, 1. And um this is how it provides energy to cells like I said, not important to necessarily know now, but we will be talking about that a lot in the future. So let's move on to the next concept

So in this video we're talking about the seventh property of cells and that is that cells engage in mechanical activities that help regulate diverse cellular function. So I'm gonna talk just about a couple of these just very briefly but know that there's a lot more that we'll talk about throughout the course. So the first mechanical activity that I want to talk about is actually transport. So transport of materials in and out of the cell is crucial to keep the cell running. So one of the ways that sell that materials are transported is actually through diffusion, you may remember from your intro bio classes and that is that movement of a substrate between areas. A differing concentration is affected by size. So not everything can diffuse, only small things can diffuse across membranes. Um and that's dependent on concentrations now, because only small things can actually do refuse. That doesn't mean that larger things never need to get across cell membranes. So how these larger molecules get across cell membranes is actually move is actually controlled through proteins found in the plasma membrane or on organelles membranes wherever it is. So these transport um of larger molecules has to happen to these receptor proteins. Um But I think it's a really important concept here that isn't necessarily hit on a bunch, but it's actually really need to think about and crucial if we're going to understand why things need to be transported and how they need to be transported and how that affects our size. So this is called the surface area to volume ratio. And that just the amount of, you know, physical surface area on the surface of the cell um is really proportional to that of the volume. So as a cell um so cell size is really governed by the surface area to volume ratio. So as a cell increases the surface area to volume ratio decreases because you can imagine a cell and say this is a cell and it's getting larger. Well this volume is increasing drastically compared to the surface area. And so this um results in an increased cell but then decreased surface surface area to volume ratio. And this is important and crucial in understanding transport processes because as the volume grows, the cell needs more materials and therefore the surface of the cell has to be really transporting very quickly in order to get all those materials in and out of the cell. So that's a really important concept that I just wanted to hit on because it may not be hit on very well in a textbook or just in class but is crucial to understanding transport and cell biology. Now a second type of mechanical activity that's important for regulating diverse cellular function is the assembly or disassembly of structural components. So um you can think of cell movement is a great example of this and the fact that you know, cells have to project themselves forward. Um and so there are a lot of movement and assembly of components where it's moving forward and disassembly where it's leaving and driving behind it. And this is super important if we're going to transport the whole cell or if we're going to move little compartments within the cell. And so all of these structural compartments are really important for cell movement um and just self support. So these two mechanical activities are really important for um classifying a property of cell. So um here in this image, I've shown a membrane here where you can see that these green proteins need to get across the membrane and so how they do that is they bind to these proteins within the membrane in order to cross to the other side and get inside the cell. And so these mechanical activities are super important and a property of all cells. So now let's move on to the next concept.

Hi in this video we're gonna be talking about the 8th and the 9th property of cells. And so the eighth property is that cells respond to external stimuli which we hit on a little bit when we talked about the mechanical aspect or the mechanical properties of cells. So um cells respond to external stimuli. There are receptors on the plasma membrane which can respond to external. So before we talked about proteins moving through receptors but now we're talking about actually binding two different signals and exerting some sort of internal response. And so um internal responses depend on having the proper concentrations of reactions and catalysts. So these are talking about you need the concentrations right for the chemical reactions you need to do in order to properly respond to external stimuli. So the ninth property of cells is that cells self regulate. They survive because they have the mechanisms internally that allow them to survive without really much external input. And so one of the main features of this is that the plasma membrane works a lot to regulate the sales chemistry and make sure that the external environment isn't the same environment that's found in the cells which is crucial for cell life. And one of the ways that it does this is through feedback circuitry which is sort of a fancy term meaning that um the product of some chemical reaction uh prevents the reaction from occurring again or has some kind of impact on the happening of the chemical reaction. So feedback circuitry are mechanisms that respond to levels of signaling molecules within a cell. So if the signaling level molecules are high and it's not supposed to be high then feedback circuitry is a mechanism that will stop that reaction from occurring. Whereas the opposite was true. If it's low and it needs to happen then feedback circuitry will also help the reaction continue until the concentrations are really right. So I think one of my favorite images of this entire thing is just this simple image here and this is just light being shined on a flower and you can see that if you first shine light on a flower. Then the second thing is that the flower is actually going to move towards the light. And it does this because it's able to interact with this external environment. Its cells are able to keep their internal structure and um it has these mechanisms in place that allow it to interact with things that are externally um in which in the environment in which the plant lives. Um So that is the eighth and the ninth topic or the eighth and the ninth concept of properties of cells. So let's now move on to a practice problem