Transcript for:
Overview of Biological Macromolecules

hello bio 111 this is chapter three biological macromolecules um i'm going to go over the entire chapter in this video again feel free to pause whenever you'd like we will reach some points where there's some activities and i will give you the chance to pause and figure it out before i show you the answer of course take notes where you feel pot where you feel necessary and let's get started okay so 3.1 section 3.1 the objectives we're going to going to understand macromolecule synthesis and explain dehydration and hydrolysis reactions those terms might seem kind of large and crazy to you maybe you don't understand them but hopefully by the end you understand the terms and what they mean so here we go so there are four major classes of biological macromolecules sometimes they might be referred to just as macromolecules sometimes you might hear them as bio macromolecules so there's carbohydrates lipids proteins and nucleic acids and over here on the right there's a nice graphic showing you the um the breakdown or on what that macromolecule might look like on a element and molecule scale very small so these are organic molecules so if you ever take organic chemistry you are going to look at mainly these four molecules and they're organic because they contain carbon so if you take a closer look at these molecules you can see there's a lot of seas in these right a lot of c's there are also c's at the points where they're not labeled and those are carbon these molecules also contain hydrogen oxygen nitrogen and some other minor elements but carbon is great because you can make four stable bonds with carbon so if we take a closer look at this lipid this carbon here can make four bonds and that's mainly why everything is made up of carbon now there's silicon as well which can make four stable bonds but it's a heavier element and we have more carbon on earth than silicon so i think that's why all organic life is based off of carbon so it's based off of these four molecules so that's what we're going to learn about um we all you also might understand that these four things are part of what you eat every day carbohydrates sounds very familiar lipids is a fat proteins and we don't really get into nucleic acids when we talk about food but these are four things that your food contain so very important to you biological macromolecules consist of subunits called monomers so monomers are like building blocks and we can stack them together to make a larger a larger unit which is called a polymer so a monomer is just one small molecule but if we repeat that one small molecule over and over again we get a polymer and so uh monomer and polymer are just the basic terms most of the time the um one of the four classes each of the four classes have their own special name for that polymer so for instance an amino acid or a nucleic acid is going to build on itself so those are monomers and polymers um but we'll get in into that a little bit more here in a bit so um not getting into specifics with that right now but monomers and polymers we can connect them in certain ways so we're going to talk about the bonds that they form so here's a breakdown of polymers and monomers you can come back to this page at any time um you might want to screenshot this this is a nice like cheat sheet to see what the monomer and the polymer are called for each of the four classes that we talk about okay all right so we can make monomers or we can combine monomers rather into polymers by going through a chemical reaction so making a polymer we're adding monomers together to make a polymer it's called dehydration synthesis big term right so dehydration synthesis two monomers added together make this small polymer and it's it's called putting together while losing water so you can see these red h and o h here these two things are going to combine and with the combination of those two things now we can form a bond so we we remove h and o h and now we have space to make a bond here so this is how a polymer can be created so we're going to lose water when we do that dehydration synthesis right so we're losing water we we're dehydrating those um monomers and we're synthesizing a larger uh molecule okay does that make sense so a water molecule formed by combining and they are combined by a covalent bond now if you want to go back to chapter 2 where it talks about bonds and covalent bonds and ionic bonds and all that you can go back and read about chapter two we're not going to get into all the bonds but covalent bond is a nice bond because it is very stable okay so dehydration synthesis leads to the formation of what of the following take your time you can pause all right so the answer is c watermers water water and polymers i combined water and polymers oh so letter c so we're going to make a polymer and then we're also making water and of course we're not making it out of nothing right so we need our polymers there to make that um we need those monomers there to make that polymer okay so the opposite of dehydration synthesis is hydrolysis so it's the opposite reverse reaction we're breaking down that large molecule into smaller molecules which usually are easy easier digested or easy to work with right a big big unit a big polymer is not easy for your body to work with they'd rather your body would rather break it down so this is digestion so big polymer right and polymers can be two um two subunits long they can be 30 subunits long they could be over 100 subunits long this is just a simplified one to show you the basics so this polymer by adding water so by drinking water and eating the polymer your body can break it down right by adding that water back to it and so now we have two monomers two subunits that are separated from each other and now your body can handle it a little bit better we can utilize those monomers um by doing other things with them getting energy from them okay say so another question you can pause here if you'd like during the breakdown of polymers which are the following reactions take place so we're breaking down polymers which should be letter a so hydrolysis is the correct answer good job if you got that right now there is a really nice video for you to watch on your on your own time there's the link there there isn't there's also an interactive about the two reactions at the bottom so if you want to copy that url down you can if you want some extra practice but um i'm going to ask you one more question before we move on all right so the you're looking at three different reactions one two and three what i want you to determine is which of those is dehydration and which of those is hydrolysis of course you're going to use one of them twice so go ahead and pause it take your time to decide okay so number one is dehydration synthesis because we are making a polymer we're synthesizing a polymer and losing water number two is hydrolysis we are taking a big polymer with water and breaking it down into two smaller parts and then the last one is dehydration synthesis so two monomers making that polymer and we're losing water and the reverse reaction would be hydrolysis so that one was kind of a which one are you talking about situation there so extension what purpose does drinking water serve well it's digestion right we need water to break down those giant polymers if we're dehydrated then we can't do digestion properly so that's why we need to drink water on a regular basis okay so these reactions can happen at their own rate which is okay but they can also be sped up by using an enzyme so enzymes are biological molecules they're a protein that catalyze or speed up reactions so they speed up chemical reactions um enzymes can be used for either hydrolysis or dehydration synthesis reactions they are very specific on what they do so an enzyme that breaks down um sucrose is only going to break down sucrose and then an enzyme that would build sucrose would only build sucrose okay so it could only do those certain things and there are a lot of enzymes for each um each macromolecule class there are also enzymes for nucleic acids for building nucleic acids as well i just didn't list them here um but these are the common ones that you will see i did underline the ase on purpose because most of the enzymes that you see end in ase so if you see a word that ends in that it is typically going to be an enzyme okay so some of the enzymes in your body can break down sugars right but you also are lacking some enzymes that break down artificial sugar so that's why your body can't really digest artificial sugar so things like um splenda so the soup the um sucralose that break that makes up splenda your body can't break it down which means it can't get the energy from it so it's no calories that's a no calorie sweetener because your body doesn't have the enzymes to to use it so you just kind of passes throughout your body um some of it is stored because it's actually a toxin but anyway um let's let's go on to the next section um so hopefully now you understand what uh macromolecular synthesis is and you understand dehydration and hydrolysis reactions okay next section so we're going to talk about each of those four sub classes of biological macromolecules so first we're going to cover carbohydrates so by the end of this section you should understand what the role of carbohydrates is in cells and on the outside of cells we'll explain some carbohydrate classifications and so here there's some classifications down below monosaccharides disaccharides polysaccharides hopefully you can list a couple of each of those by the end of this section okay carbohydrates typically when you hear the word carbohydrate you think sugar you think bread pasta corn fruit potatoes right those are things that contain large amounts of carbohydrates so they provide our energy in the form our body energy in the form of glucose so carbohydrates are mostly made up of glucose or some form like glucose and so there are really large polymers that your body has to digest break down do hydrolysis right and um then we can use the monomer subunits okay so typically you're going to see carbohydrates represented in some form like this so ch2o to the end multiplication factor so c6h12oc is typical glucose so that is just one monomer of a carbohydrate right so that's we're going to have twice as much hydrogen than carbon and oxygen is basically what it's saying and same with that ratio down there carbon to hydrogen to oxygen so three main subtypes are monosaccharides disaccharides and polysaccharides okay so monosaccharide is a monomer disaccharide is two monomers together and then a polysaccharide is more than two all right so monosaccharides monomers of carbohydrates typically one ring they usually have three to seven carbons so remember all of these four um divisions of macromolecules are going to be carbon based so we're very interested in carbon here in this chapter um they have one ring three to seven carbons they usually end in the suffix o s e now that's not all the time but it's usually it's most the time so glucose common one right fructose and then galactose so these are the typical monosaccharides that we're going to see in the real world okay so the i know probably blowing your mind with this um page you're like whoa it's too much um so here we go structural isomers formula so an isomer it has the same chemical formula but it's just arranged a little differently so glucose galactose and fructose here they all have are c6h12o6 but they're all arranged a little differently so you can see this end one is pretty obvious that double bond to oxygen is in a different spot and then glucose and galactose the um middle parts here are arranged a little differently so these are different enough to call them different monosaccharides right and they come from different places so glucose is what plants synthesize during photosynthesis okay galactose is part of lactose so milk so animals make galactose we make galactose fructose is part of fruits so the storage portion of plants is where fructose comes in it's very sweet and so these are again three monosaccharides so hopefully you can name these three when i when i ask what is a monosaccharide you say oh well it's glucose it's galactose it's fructose a monosaccharide is just one subunit right it's a monomer so we can add these things together to make polymers okay okay so normally if you had um if you had a model making kit i would have you create one of these on your own but you don't so it's okay we can um go on to the next slide so monosaccharides are what glucose galactose fructose so disaccharides are combining any combination of those monosaccharides together so remember glucose is made by plants fructose is the fruit part is made in the fruit part of the plant if we put those two things together we get sucrose so that is a disaccharide there are two monomer subunits um sucrose is a table sugar so the sugar that you buy at the grocery store that comes in that paper bag that's sucrose so it's a disaccharide which is pretty neat um they are combined together through what's called a glycosidic bond it's just a nice term for covalent bond it's a specific term for a disaccharide um covalent bond okay so sucrose let's look at some other disaccharides maltose and lactose are other disaccharides so maltose is grain sugar so that's two glu glucoses added together so grain sugar is like wheat barley rice those types of things make maltose and that's their storage carbohydrate right so when you eat rice or you eat oatmeal or bread you're consuming a lot of maltose lactose again so that's what animals make that's what we make milk sugars what it's called and that is a glucose and a galactose together okay so two of those monosaccharides added together and then we already covered sucrose which is glucose and fructose added together okay so again disaccharides are just two monomers two monosaccharides added together so a polysaccharide is a large large carbohydrate it has more than two subunits and it can be extremely extremely large so their molecular weight weight could be over 10 000 amu which is huge um glycogen is one polysaccharide that's in our bodies we use it as a storage um a storage function animals use it as a storage carbohydrate so it's stable when we run out of food or we're not eating enough food our body will break down glycogen so it's nice it's a nice storage function it also insulates our insides so polysaccharides can be huge they can be branched they can be straight they can be um consider they can consist of multiple types of monosaccharides so we looked at the disaccharides and they had different combinations polysaccharides can also have different combinations so this is what i mean by straight or branched amylose is a starch and so is amylopectin but this one's branched here so that one's straight so they're just different on how they're arranged um these are sources of these starches so they tend to be stored in plants right okay cellulose is another polysaccharide made by plants but this one is placed in the cell wall so remember plant cells they have a cell membrane like normal and then they also have a cell wall which is on the exterior of that cell membrane and its um cell wall is just mostly for structure remember plants don't have bones so they have this tough cell wall which is made of cellulose and that is a polysaccharide okay so it's nice and straight and it's just this repeated over and over um for forever right so nice fibrous structure not easily broken down by animals chitin is another polysaccharide and this is in the exoskeleton of arthropods it's also um in the cell wall of fungi so fungi remember they're not plants they're their own thing and so they have different structures so their cell wall or their cell wall like structure is made of chitin and chitin's pretty neat it's made of nitrogen which is different than most polysaccharides okay so back to glycogen glycogen is what we have this here is one molecule of glycogen so each of these red little structures is a monosaccharide just take a second and look at how many there are crazy how big it is but it's a really nice structure and then there's a um so each of the red is the is the carbohydrate portion this middle portion is a protein which helps keep it in in place so each of these red structures again so it's a monosaccharide and that's where that's how we store extra um extra carbohydrates so when we overeat and we eat too many carbohydrates our body starts to store them as glycogen so your body usually stores glycogen in your liver it also stores it in adipose tissue which is fat tissue it could store it in your blood uh and it can store it in your muscles as well um so storing it in your blood is probably the worst place for it especially if you're a diabetic um but that's where glycogen is stored and it is made to be broken down so hopefully your body will break it down in the future there's a nice video here for carbohydrates review if you want to go back over that um but let's go on to the poll question which of the following is not an extracellular matrix role of carbohydrates so extracellular matrix is just referring to that outside covering of the cell so that was like chitin in the arthropod that was like the cell wall in the plant cell wall and the fungi um storage in those plant structures so the correct answer is a protect and insects internal organs from external trauma so that's not a role of carbohydrates for insects but um in animals if we were talking about protect in animals internal organs yeah that would be the correct answer so that would make that answer correct all right so that's the end of carbohydrates hopefully now you can discuss the role of carbohydrates explain some classification and then list some common monosaccharide disaccharide and polysaccharides so next up we have lipids so we're going to describe the four major types of lipids we will explain the role of fats and we will differentiate between saturated and unsaturated fatty acids so you probably saw these listed on a nutrition label before so we're going to talk about those we will discuss phospholipids and we will describe what a steroid is and what cholesterol is okay so lipids are a diverse group of nonpolar hydrocarbons so nonpolar means that the molecule is hydrophobic so that means it does not like water so hopefully this meme over here will help you understand that so here is a lipid here's water they can't be together because the lipid hates water it repels water and they're a hydrocarbon because there are a lot of carbons and a lot of hydrogens um added together to make this molecule okay so sometimes you might hear a hydrocarbon as a term when when somebody talks about gasoline um and so that's kind of the same thing but um let's talk about lipids here in a sec all right um let's get back to lipids so lipids functions of lipids long-term energy stores um they provide um lasting energy so it takes your body a little longer to break down lipids your body breaks down carbohydrates pretty quickly but it takes it a little bit longer to break down lipids lipids also help insulate animals from the environment so this otter here has a lot of lipids on its fur so it has like a waxy coating on its fur but it also has a layer of fat underneath of its skin that that helps insulate it um lipids also serve as the building blocks for some hormones and they are an important component of cell membranes okay so the four classes of lipids so remember this is one of our objectives four classes are fats and oils waxes phospholipids and steroids okay so we're going to talk about each of these here i'm going to break them down for you tell you what they are so here we go all right fats and oils so fats contain two components this is a fat molecule here okay fats and oils remember fats and oils not all lipids are fats right so this is just the fat which is part of a lipid which is um one classification of a lipid so they are made up of a glycerol which is here and then they are made up of fatty acid tails which run that way so this is called a triglyceride and it is a triglyceride because there are three fatty acid tails and that glycerol head so this glycerol is actually technically an alcohol because it has a lot of those ohs it ends in the oil that's how you know it's an alcohol easy to remember that one right so a triglyceride is an alcohol glycerol and then three of those fatty acid tails so these fatty acid tails can be different lengths um they can be different structures which i'll show you in a second so they might not always look like this so just keep that in mind when we get to the next few slides okay so this is a fatty acid tail this is a saturated fatty acid tail so when i say saturated it means that it's saturated with hydrogens or you could even say saturated with single bonds so all of these carbons have single bonds to hydrogen there are hydrogens on each side of those carbohydrates so they are very straight they can be packed very tightly and typically when we're talking about food saturated fatty acids are solid at room temperature because they can pack in so tightly so that's butter that's lard or fats and meats things like coconut oil cheese even cream those are things that are solid at room temperature so these things are also associated with cardiovascular disease your doctor has probably told you or somebody has told you to limit saturated fatty acids in your diet because they are not that great for you of course a little bit is okay but not a lot unsaturated fatty acids are better than saturated because they have this bend to them so usually they contain at least one double bond so when i say an unsaturated fatty acid i mean they are unsaturated with hydrogen so look at there's two that are missing right here so they're unsaturated you can have monounsaturated fats which is just one double bond or you can have polyunsaturated fats which is more than one double bond um most unsaturated fats are liquids at room temperatures so those are oils so monounsaturated fats are like olive oil canola oil peanut oil sesame oil avocados or avocado oil and most nuts have monounsaturated fats in them polyunsaturated fats are things like corn oil sunflower oil soybean oil seeds cold water fish so those are the better fats to consume for your health so what's the deal with trans fats i'm sure you've heard trans fats are not good for you they do have a double bond but that double bond does not make it curve like it usually does so this is a it's called a cis unsaturated fatty acid and this is a trans unsaturated fatty acid so that cis is just referring to that the hydrogens are on the same side and then the trans is referring to the hydrogens are on opposite sides of each other so cis fatty acids are good they have a kink in the chain typically they're liquids at room temperature trans can be straight um typically hydrogenated oil you've probably heard that term before this is how trans fats are made through processing so hydro hydrogenated oil is not good that's a trans fat foods with trans fat may increase ldl cholesterol which is not a good thing either okay so cis unsaturated fatty acids are great but double check that nutrition label to see if there are also trans fats and if there are trans fats it's not good so if you have a modeling kit you can practice creating one um if not we can move right along all right lipid so fatty acid these are essential fatty acids um lipids that are shaped in this hook like pattern which is kind of funny to me are are things that are from fish hook like pattern they're from fish it's kind of funny um so these are called omega fats there's omega-3 and omega-6 fatty acids so salmon trout tuna are sources of omega-3 which is good for a healthy heart we cannot synthesize omega-3s ourselves so we have to get them from our diet so that's why eating fish um once a week or a couple times a week is a good thing to do omega-6 fatty acids are found in oils so if you cook your fish in some oil then you've you're doing double duty all right so poll question saturated fats all have what except saturated fats have all the following characteristics except what that is letter d they tend to dissolve in water easily so remember our first couple slides about lipids they are hydrophobic so they do not like water which means that they are not going to dissolve in water either all right going on so waxes i only have one slide for waxes because they are so different depending on which wax you're talking about so waxes um they can have chains they can have rings on them they are hydrophobic just like the rest of lipids they don't like water they prevent water from sticking to the surface um typically found on aquatic animals aquatic birds you know um and and plants so like this holly bush here very waxy helps protect it all right phospholipids so phospholipids are found in the cell membrane so all the cells in your body have a cell membrane and phospholipids make up that membrane so phospholipids are different they are almost like almost i say almost like a triglyceride so they have that glycerol backbone but instead of that third fatty acid tail they have this part instead which is a phosphate group so that makes them have a few different chemical chemical characteristics so phospholipids typically look like this in a molecular scale and we might refer to them like that when we draw a cell membrane so they have this head region which is where the glycerol and the phosphate are and then they have the tail region so the head region is going to be hydrophilic so remember lipids hate water okay lipids hate water but phospholipids can tolerate water because of that phosphate group which is located in the head region so the head region can face towards um the liquidy water portion of the cell and then the outside portion of the cell which may contain water which is great and then the inside portion where the fatty acid tails are they still hate water so they're going to be protected in that sandwich layer i like this meme over here it says hey guys look i have a water gun and they're all like no moving away from the water so they don't like it okay steroids steroids are the last type of lipid that we'll cover steroids have these rings to them they still um they're like other lipids they don't like water many of them will have this short tail to them sometimes they might not have a tail at all this one here is cholesterol and this one is cortisol so cholesterol is a steroid i bet you didn't know that so learn something new um so again they are hydrophobic they do not dissolve in water cholesterol is the most common steroid in your body it is made by the liver it is a precursor to other hormones so testosterone estradiol those are hormones right and they're made up of steroids precursor to vitamin d and then precursor to bile salts as well so steroids or cholesterol is not all bad of course too much of a good thing is is bad right um but we still need it so steroids are not a carbohydrate right they look like a carbohydrate a little bit because they have that ring structure but they're not a carb carbohydrate because they are hydrophobic they don't like water so phospholipids are an important component of what letter a the plasma membrane of cells okay so that brings us to the end of lipids so hopefully now you can describe the four types so remember the four types are what fats and oils phospholipids waxes and steroids um we store glycerol or not not glycerol glycogen in our body for later use that's our way of storing fat we can also store fat to help in insulate our body we can use fat as an insulation at a waterproofing saturated fats are those straight chains they are salads at room temperature unsaturated cis unsaturated fat are the bent ones those are liquids trans unsaturated fat are the straight ones with double bonds those are bad those are solids as well describe phospholipids so phospholipids make up the cell membrane um we'll talk more about the cell membrane when we get to chapter five um the basic structure of a steroid is a ring structure usually has four rings um cholesterol is the steroid also makes hormones and it helps make the plasma membrane um fluid which we may not have talked about but it does it helps make it fluid because it helps provide some spacing in the membrane all right so 3.4 proteins we're going to describe functions of proteins we'll talk about the relationship of amino acids and proteins we'll talk about the four levels of organization which is what this gif is showing you and then we will talk about the structure and shape of proteins and why that's important so primary secondary tertiary coronary is the four level are the four levels of protein organizations we'll talk about that there in a second proteins are the most abundant organic molecules so we have a lot of protein in our body we have a lot of different protein in our body so proteins have a very diverse range of functions but each protein is very specific on what it does so you can have regulatory function proteins structural function protein proteins that provide protection proteins that that transport molecules proteins that act as enzymes and we already talked about enzymes right so we know how specific enzymes are and then proteins that are even toxins for your body so here is a list of protein types and functions this is straight out of your textbook so you can see here some digestive enzymes that we've talked about before so that helps break down food and it also could help build other enzymes um let's see storage enzymes or store it not inside storage proteins provide nourishment of like an embryo or seed seedlings excuse me um defense and all that so um enzymes again so i told you we'd come back to enzymes enzymes are a special protein um they help speed up reactions so the reaction could be that it's building something or it's breaking something down so if we're talking about an enzyme in your stomach that is breaking things down that would be a catabolic enzyme catabolic enzyme okay if we're talking about an enzyme elsewhere in your body that's building proteins so let's say like in a muscle that's going to build protein that's an anabolic enzyme so anabolic i remember that one because it has an a so it's like adding things together so adding things building things that's an anabolic enzyme okay catabolic is the opposite so this is what an enzyme would look like on a smaller scale of course each of these would be little molecules in here this is just a simplified version even though it looks very complex this is an enzyme that catalyzes the conversion of maltose to glucose so we're breaking down maltose it has two um it's a disaccharide right we're breaking it down into its subparts which is glucose two glucose so this curly um white white shaded object here is the the enzyme the protein itself and then this little space here is where it's going to break down those parts so enzymes again very specific it only um only functions on one thing so this enzyme is only ever going to break down maltose it's not going to break down fructose or um or sucrose right because they just won't fit the substrate would be different so it's only going to fit that one substrate so proteins are made up of amino acids that's the monomer the protein is the polymer so their fundamental structure is this right here so this is an amino acid that's just one now we're going to link these together right link these together so this is the separation by um by what dehydration synthesis right so this is a this is two amino acids together so each amino acid and i say each because there's 20 different amino acids each amino acid has a carboxyl group it has this amino group it has an r um side chain so you might say like oh i don't know i've never seen an r before when we're talking about molecules this r is just a placeholder for the different amino acid um our side chains so again there are 20 amino acids each one has a different r group the r group can be different in the chemical nature that it has so it could be nonpolar it could be polar which means it's going to repel or like water it could be positively charged it could be negatively charged it could be a non-polar ring um like our guy here this is a ring so let's take a look at each of them here's 20 common amino acids so again these um the things that you are looking at are the things shaded in blue so those are each of the r groups the things not shaded in blue is the rest of the amino acid that remains the same for each amino acid okay so again the only thing changing on each of these is what's shaded in blue and that determines its chemical nature so we have glycine alanine valine these are nonpolar um these are nonpolar r groups and then down here things like cysteine serine those are polar and then lysine argonine histidine are positive positively charged you can see the little plus signs here then there's negatively charged versus asparagus asparate and glutamate negative right and then you have those ring structures which are nonpolar so each of these amino acids have different chemical makeups there they have different chemical formulas and if we arrange them in certain ways they're going to cause the overall function of the protein to be different so if we have a lot of nonpolar nonpolar amino acids linked together it's not gonna like water right so it's gonna be in a place that doesn't like water so maybe it'll situate itself in the plasma membrane okay um let's see let's um which amino acid is this guy here so this part is the cooh that's our nitrogen group there and this where my red dot is is the central carbon so this bend and then this ring is the amino acid so which amino acid is that right there and if you said phenylalanine then you'd be correct right because it has that carbon which is represented by that bend and then it has that ring so that's phenylalanine so that's a nonpolar aromatic amino acid and again there are 20 of them so that's just one of the 20. all right so we can make polymers we can make proteins by linking the amino acids together so they're linked what's in what's called a peptide bond which is a type of covalent bond again this is dehydration synthesis so water is going to be released right this h and o h are going to combine and they're going to be shuttled off somewhere and then that leaves room for a bond to occur so again that's in the peptide formation so proteins you might hear them called polypeptides protein polypeptide typically interchangeable and they're formed by peptide bond linkage all right so protein shape is based on four levels of structure primary secondary tertiary and quaternary we're going to look at each of these a protein shape is very critical to its function so each of these structures if something happens and that structure is not what it should be then the protein's function is not going to be what it should be it's not going to occur correctly it's not going to happen so the first one is primary structure um primary structure is the unique sequence of amino acids so it's which amino acid are we using and then what order is that amino acid in with the other amino acids so remember we had a lot of different amino acids there was polar there were non-polar charged so on and so forth so which amino acids we use in which order they're in is very specific and it is based on your genes in your dna so your dna is going to tell your body like hey we're going to make uh insulin right so this is insulin um and it has to be in this order all the amino acids have to be in this this exact order or it's not going to function correctly it's going to be a dysfunctional insulin protein so primary structure is um very specific in every protein that we make another protein that's very common is hemoglobin and hemoglobin can become dysfunctional and it can become sickle shaped and the sickle shape is only because of one amino acid substitution so instead of this glutamic acid there's a valine instead so if you look threonine proline glutamic acid lysine threonine protein valine lysine so just that one substitution causes this entire shape to be sickle shaped and so if you know what sickle cell anemia is that's not a good thing to have it makes breathing difficult it makes a lot a lot of health issues and so it's just that one substitution in the primary structure that causes that that to happen it's crazy that it's only that one little thing that makes that problem um the next structure is secondary structure so secondary structure creates either a pleated sheet or this curlicue helix and that is just um due to hydrogen bonding between the carbon the cooh group and the nitrogen group on each amino acid so if you notice here's our little r group our group our group so these are each amino acids that we're looking at so the interaction between two adjacent amino acids would create these structures so again helix and pleated sheet tertiary protein structure is more chemical interactions but they are between r groups instead of cooh and n groups so they could be things like ionic bonding which is positive and negative attraction of r groups they can be hydrophobic interactions so those would be contained like on the inside of a protein right hydrophobic they don't like water so they would probably like be protected a little bit in the center of a protein um if there are self sulfur on the r groups those are going to be linked in a disulfide linkage and then a hydrogen bonding can also occur still so these are tertiary structures of proteins some proteins end at this point where they only have a tertiary structure most proteins have a quaternary structure so a quaternary structure would be other tertiary structures added together so this red orange blue and green those are separate units so those are separate proteins but if we add them together we get a quaternary structure and the weak interactions of those subunits help create the structure and help stabilize the structure so the one that we're looking at there is actually hemoglobin okay and then a red blood cell contains about 270 million of these protein molecules just one rbc contains 270 million of those and right in the center of each of these is where oxygen will bind so to sum up protein structure these are the four so primary secondary tertiary and quaternary okay so i said at the beginning where um we went over the objectives for protein that structure and function go hand in hand so if we denature the protein we would change its function and we might actually um we might actually change it to where it can't change back so chemical interactions are broken in the protein which causes its function to change so changes in ph um changes in temperature and interactions with other chemicals and maybe even like radiation would cause denaturation of a protein so if you think about an egg an egg has a lot of protein in it when we put it in a hot frying pan it's going to change color and that actually changes the protein shapes in the egg itself um if you take a if you take a protein from your stomach like pepsin pepsin likes a very low ph like a ph of 2. if you take pepsin and you put it in like a higher ph like ph 7 it's not going to work anymore because it's outside of its normal range so changes in ph from where the protein likes to be situated are going to cause deformation of the protein all right if you like review videos here's another good one that i found online um poll question to sum up proteins so mad cow disease is an infectious disease where one misfolded protein causes all other copies of the protein to begin misfolding this is an example of a disease impacting which structure what do you think that would be letter c so tertiary structure so one misfolded protein one misfolded tertiary structure causes the rest of the structure to begin to be misfolded all right so now you should understand these ones on these objectives for proteins hopefully you should you can describe the function on the relationship between amino acids and proteins so that's the monomer that's the polymer um explain the four levels primary secondary tertiary quaternary and the ways where we can denature so changes in ph temperature interactions with chemicals and even radiation all right last but not least nucleic acids this one will be short we're going to describe nucleic acid structure we're going to look at dna and rna so later on in the course towards the end we talk more about dna and rna so we're just going to cover some of the basics here nucleic acids constitute genetic material genetic information of living organisms all living organisms have nucleic acids so living organisms rely on nucleic acids to record information and save information and then they pass that information down to their offspring two types of nucleic acids are deoxyribo nucleic acid and ribo nucleic acid so dna and rna the location of nucleic acids is going to be in one of four places or multiple places um the nucleus of eukaryotic cells the mitochondria organelle the chloroplast organelle and then in prokaryotic cells they don't have a nucleus so it's just hanging out in there loose or um connected to the cell membrane but we'll talk about prokaryotic cells later on all right nucleic acid so nucleotide the nucleotide is the monomer so the monomer of a nucle or a nucleic acid nucleotide right so nucleotide has three parts so an amino acid that we talked about in protein has a few parts in it right a nucleotide also has a few parts so again nucleotide is the monomer it contains a nitrogenous base which could be one of five things it has a pentose sugar and then it has um a phosphate group and it could have one it could have two it could have three um this sugar could be deoxyribose or ribose okay so only one of two things there so that's this is a basic monomer this is a basic building block of a nucleic acid so i know when we talk about dna and rna we typically just refer to like the letter like t a c g or u but keep in mind that it also has these other two parts connected to it okay so the polymer can be dna or rna and again here's our nucleic acid there our nucleotide so it has the phosphate the sugar and then the nitrogen group and those are going to be linked together phosphate and phosphate to sugar so that kind of forms a backbone right that forms a backbone and then the nitrogen groups form what we like to call the rungs of the ladder right like that so a lot of the time uh we're gonna have a double helix especially when we're talking about dna and then in rna we only have a single strand it might form into a helix like this it might fold on itself rna is not that stable so it will break down over time dna however is more stable so here is just the compare and contrast of dna and rna so dna and rna both both carry genetic information but rna is directly involved in protein synthesis dna only stays in the nucleus when we're talking about eukaryotic cells it's only going to stay in the nucleus the rna can enter and leave the nucleus um dna is a double helix like her hair and then rna can be a single helix or single stranded deoxyribose is in dna ribose is an rna dna is made up of these four bases and then rna is made up of these four bases so rna is going to have uracil instead of thymine and that's only because thymine is a little bit bigger and uracil is smaller and um cheaper to make in molecular terms so that's really the only difference okay so dna is involved in what's called the central dogma of life and the central dogma is basically saying that we go from dna to rna to protein so that is the um the streamline of information right so we have dna we use that dna to make rna we use that rna to make protein okay so that's what the central dogma is francis crick um first articulated the central dogma in the 50s all right so here's another nice video that goes over nucleic acids all right final poll question a nucleotide of dna may contain what so a nucleotide remember is the monomer dna is the polymer so each nucleotide contains what three things and it has to be for dna so it's going to contain c so deoxyribose which is our sugar that is a dna base thymine and then phosphate group of course okay so hopefully now you should be able to describe nucleic acids their structure and the two different types so dna or an rna hopefully you can explain dna structure and role and then rna structure and role and then here is a nice gif which goes over the nucleotide structure which again is your monomer okay and that is it so you can go on going back through the lecture if you'd like you can hit those review videos if you are unsure of some parts of the video um there are review games that i've created that you can use to review this but make sure you complete your reading assignment your lab and your quiz for the week have a great day