all right folks welcome back um we are in the second lecture on chapter two on body chemistry or the chemistry of life i've titled it a couple different ways but it's an overview of chemistry as it applies to the human body okay last time last lecture we ended up here talking about water okay um so let's just review where we've been so far this is the um the things that we've talked about already in this chapter we talked about matter and energy okay we talked about atoms and the way that they form bonds using those electrons okay the bond formation okay making bonds and breaking bonds that is called a reaction okay there's different types of reactions we talked about those reactions have a speed or a rate and they require energy exchange and then we talked about molecules when we begin to form many many bonds into a much larger structure than just a single atom we form molecules and molecules fall into two categories okay inorganic and organic okay inorganic and organic inorganic is defined by lacking hydrocarbons okay hydrocarbons define something that is organic and so we started talking off talking about water and the properties of water okay so back a couple of slides here we went through the four or six properties depending on if you're the notes or in the um the powerpoint of the note sheet okay some of these properties of water that make it so valuable and important as a as a medium in which biology exists okay so we're going to finish off talking about water and then we're going to talk about ions and electrolytes salts acids acids and bases ph and buffers that will close out our discussion about inorganic molecules and then we'll close off by talking about organic and this looks like just a tiny little section here of the whole chapter but in fact this is almost half of the material because what we're covering here is really a condensed version of a biochemistry course okay now we are this is not a biochemistry course so we will not be learning it in the detail that you would learn in about chemistry course however these are the this is an overview of a good biochemistry course now there's a lot more that goes into that about enzyme kinetics and pathways and such but this is kind of approaching biochemistry all right so we've already addressed these things about water we talked about how water is a polar molecule the electronegativity difference between the oxygen and the hydrogen pull on the electrons more strongly with the oxygen and it therefore gives it a partial negative charge so um that's what we see here okay here's the oxygen here are these two hydrogens and due to this difference in electronegativity which we if you remember looking at that heat map table that showed the different electron activities of different chemicals it produces this partial negative charge here on the oxygen side and this partial positive charge on the hydrogen side okay that property drives all of the other things that we just learned about for water this um this dipole moment is sometimes called a dipole just means it has polarity okay one side is negative and the other side is positive now it's not a full charge it's a partial charge and that's kind of hard to understand but that's what this little delta symbol is means it means partial and due to that this these properties therefore water has a certain behavior in a container that gives it surface tension its attractiveness its ability to dissolve other molecules and in fact we can dissolve things like table salt here we can see a molecule of chloride is being hydrated by water molecules if you look closely you'll see that this negative charged chloride all of the blue hydrogen molecules are kind of facing towards the chloride because that is in fact where the partial positive charge is and then the sodium you'll notice that the water molecules are kind of flipped around that is all of the oxygen molecules are facing that positively charged sodium okay so that's this hydration bubble or hydration layer that is kind of surrounding the chloride and surrounding the sodium is due to what is favorable for the polarity of the water molecule okay so that's the ability of water to dissolve okay ions and electrolytes which we'll get to a little bit later okay glucose also has the ability to dissolve in water because it does share some some um polarity okay chloride and sodium have full negative and a full positive charge so its solubility is very high okay sugar just has partial charges around it so it's not quite as soluble as sugar although if you dump table sugar into a glass of water as we all probably have experienced you'll see that it dissolves quite readily all right so properties of aqueous solutions remember when we see this word aqueous we just it means water in water okay so electrolytes we have to learn about electrolytes and body fluids so what the heck is an electrolyte okay it is something is a solution that has ions in it that can carry an electrical charge okay so it usually means that there's solutes in there that have full charge or even partial charge the most commons that ones that we'll talk about are elements like sodium potassium calcium amongst others okay chloride those are all electrolytes and we'll talk about that in the context of nutrition and the body's body fluid balance okay body fluid balance and these electrolytes is super critical these levels in the blood and in the lymph and other bodily fluids is very very impactful for health okay so here is a table listing some several common electrolytes that we see in the human body okay so sodium chloride just good old table salt we're probably the most familiar with it dissociates in water into a sodium ion and a chloride ion that's carrying a full positive charge for sodium and a full negative charge for chloride in a very similar manner all these other electrolytes dissociate or dissolve in water okay potassium here potassium chloride calcium phosphate sodium bicarbonate okay magnesium chloride etc these are very very important electrolytes because when you add these molecules into water they dissociate and become ions okay an ion is a molecule that has a full charge a plus one a minus one even a plus two or minus two some of these have um more than one unit of charge associated with them okay calcium because of its place on the periodic table carries a plus two charge it will always be plus two okay again we'll come back to this when we talk about the cardiovascular system and the especially the urinary system we will be talking about these ion levels in much more detail okay we will also talk about these in the context of the nervous system because the way that neurons send and receive signals okay the electrical impulse is really a movement of ions and the movement is of sodium and chloride and calcium in some cases all right so um another major theme or major concept that is true in the human body the first part of the lecture we talked about how matter and energy the exchange between matter and energy is a major concept we talked about metabolism and all the biochemical transformations that are exchanging matter and energy okay that's a key concept the next key concept is the concept of water versus oil okay if you've had your favorite salad dressing and if it's like a vinaigrette okay not so much ranch but water and oil don't mix okay and the basis of that is rests in their chemistry okay that is the hydrophobic and hydrophilic nature of any um any solution or any molecule is based on its ability to be attracted to water or more fearful of water and attracted to lipids okay so water versus oil okay or the hydrophobicity or the hydrophilicity okay hydrophilic means you're attracted to if you're an audiophile you love music audiophile philic means attraction okay phobia means fear of okay so hydrophobia hydrophobic means a fear of water and so there are two terms here that are interchangeable you could say hydrophilic or you could say lipophobic okay lipophilic lipid means um fats or lipids and then we're at either philic or phobic okay so if you hear those two terms hydrophilic and lipophobic are this are synonymous and um hydrophobic and lipophilic are synonymous all right anyways major concept here okay something that is hydrophobic means that is attracted to water okay filos means loving okay hydrophobic water fury okay this precept governs all of um biochemistry okay the way that a cell membrane is formed okay or different vacuoles and actually how proteins fold is dependent on this relationship okay so it's a very very critical thing as we talk about molecules in solution okay you have different types of molecules that go in solution can have a colloid colloid is a solid solution of very large organic molecules for example blood and plasma so a colloid is really has big molecules that don't dissolve a red blood cell will never dissolve because it's a large molecule proteins don't dissolve okay but you could have a table salt well that would dissolve into ions okay so a colloid a suspension is something that will um the molecules are so big that they tend to settle out given enough time so again a salad dressing is a good um example of this okay an italian salad dressing where you have the vinegar part you have the oil part and you can shake it up and give it some mixture before you add it to your salad but if you just set it on the counter over time it will slowly separate okay because it's water and oil that vinegar is aqueous so that's really a suspension there's all the herbs and goodies that are in that salad dressing will separate out because they won't dissolve okay concentration is merely a way of measuring the amount of solute in a solute in the solvent okay moles per liter or milligrams per mil these are common units of measure for concentration all right ph okay as we're working our way down through these inorganic molecules we talked about water and we talked about a little bit about ions in electrolytes and now we need to talk about acids and faces okay acids and bases which is the basis of this concept called ph okay ph is a measure of the concentration of hydrogen ion okay that's what ph means okay it's actually kind of percentage hydrogen it's not really percentage but it's parts okay and so hydrogen ion is really just a proton so if you hear something is protonated or deprotonated that's kind of bio biochemistry lingo but protonation means that an acid it was acidified okay that was a free proton is the same as a hydrogen ion same thing there's synonyms okay proton and hydrogen ion because it's just missing its electron okay so if you take the electron away from hydrogen all you're left with is a proton so and that's really the role of an acid is to add protons to the solution and therefore in turn they get added to other molecules we know water okay water drinking water in our typical water that we interact with is of a neutral ph that is the amount of hydrogen versus the amount of um hydroxide is balanced okay there's not more hydrogen ion than hydroxide ion they are balanced okay and so we call that neutral ph which we call a ph level of seven okay so ph um is a measure of hydra of hydrogen ions but if and when ph gets very low this concentration gets very high when the opposite of ion here hydroxide gets high then our ph will get high okay we'll talk about that in subsequent slides here okay so things that are defined as acidic are the ph is lower than uh seven okay this means that there's a high hydrogen ion concentration and a low hydroxide ion concentration things that are basic have a ph that is higher than seven okay and then the reverse is true here our blood is buffered in a very tight window of ph okay and it very rarely moves because of the buffers that are inherent in our blood okay between 7.35 to 7.45 is the normal physiological ph of blood all right we measure ph on a ph scale and that scale is logarithmic okay it is log 10. that is for each unit one unit okay let's say we go from seven to six that's actually a tenfold jump in the hydrogen ion okay so if you go from seven to six that's ten fold from six to five that's another ten-fold so from seven to five is ten times ten is a hundred fold okay so it's logarithmic okay here's that scale okay so here's neutral ph ph of seven okay and the easy thing kind of the trick without learning all the mathematics that are really at the basis of this is to look at the negative exponent um here below it okay so this is 10 raised to the minus seventh that's 10 to the minus seventh concentration of hydrogen ions in water okay so there's an equal amount um 10 to the minus seventh of hydrogen ions as there is hydroxide ions they are equal they're both at 10 to the minus seventh as we move into a more acidic ph okay the ph number goes down what we see that number increasing when we have a lower exponent that means the number is higher that's the confusing thing about exponents but if you just look at the negative exponent 4 okay ph of 4 means 10 to the minus fourth ph of 3 10 to the minus third ph of 2 10 to the minus second or two okay so in that sense it's very easy when you're looking at concentrations of hydrogen ion okay as i said here this is kind of physiological ph or neutral ph and their blood is just slightly alkaline 7.4 on average okay there's some other substances here that we need to note saliva and milk is slightly acidic tomatoes and grapes and other um acidic um fruits and vegetables like citrus um have some acidity okay stomach acid notably here extremely acidic okay right now your stomach is full of acid now that acidity increases as you begin thinking about food or eating food because your gastric juices begin to be secreted in higher concentration but normally you have a very acidic stomach environment and you're thinking to yourself how does that even work how does my stomach maintain such a dangerous ph well there's built-in protection in the lining of the stomach there's a layer of mucus that is protective and the sphincters at the bottom at the top of the stomach are closed very tightly and it does not allow those juices outward okay unless you have you know acid reflux and you get heartburn right so that's your when your sphincters might open up a little bit you have some acid reflux and it starts going up into your esophagus and you get that burning sensation that's because the acidity is escaping the stomach and entering up into your esophagus can you get all the burps and belches and a little bit of acid that's going up does not feel very good because the acidity is burning the lining of the esophagus okay the stomach can handle it no problem the esophagus cannot handle it and that's why it's painful okay anyway stomach acid that is very important for the job of the stomach which is digestion okay a key thing that acidity does is to influence the enzymes that are active in the stomach so you have all kinds of digestive enzymes that require a very low ph for optimum activity okay they are only exist in the stomach okay they would be not active in other parts of the body okay which would be a ph approximately seven okay 7.4 okay so that's acidity okay low ph now we go into alkaline or basic okay alkalinity or basic that is those are synonyms and again we're going into a higher ph talk about ocean water slightly basic household bleach okay about a ph of nine household ammonia about a ph of 11 to 12. okay oven cleaner very very caustic it's basically straight up sodium hydroxide okay potassium hydroxide sodium hydroxide those are very very strong bases okay they're adding lots and lots of hydroxide ion to the to the environment all right so what is the definition of an acid an acid is a solute that adds hydrogen ions to the solution okay it's a proton donor so every ask if you think about some of the most powerful acids like hydrogen chloride okay hydrochloric acid hydrochloric acid is a very strong acid it completely dissociates chloride leaves grabs the electron from the hydrogen and now that hydrogen is just the the hydrogen ion is just floating around in solution and likely if another molecule is present in that solution like a protein some innocent bystander proteins just sit in there and it gets protonated that is the hydrogen ion gets added to one of its functional groups it didn't want that but because the acid is there that occurs and that can mess up your proteins okay so strong acids dissociate completely okay like hydrochloric acid a base okay what's the definition of a base it's a solute that removes hydrogen ions from a solution or the flip side of that you can think about is adding hydroxide ions to solution so strong acids and strong bases are something that you learn about in a chemistry course but in fact in the physiological context in the human body we don't often talk about strong acids and strong bases we talk about weak acids and weak bases and they are have the same properties but they their tendency to to dissociate in an aqueous environment is lower okay so they're more of a weak acid just like the name implies and that means that they don't fully dissociate there is some balance to their where that hydroxide ion or the hydrogen ion goes okay so um salts okay so um when you add a strong acid and a strong base to each other like sodium hydroxide and hydrogen chloride okay or hydrochloric acid when you add those together ironically you get water and salt because the sodium chloride from the acid and base combine into table salt now you'd have to dehydrate this and evaporate all the water to form the salt again but this is salt and salt is a solute that dissociates into cations and anions remember a cation the t there is to remember that as a positive charge that would be sodium and the anion is the negative charge that would be chloride in this example all right so we've learned a little bit about what what ph and acid bases are um that leads us into this next topic which is so vital for the physiological physiological context which is a buffer okay what is a buffer a buffer is a weak acid and salt combination that resists rapid change in ph okay it's a weak acid salt combination that resists large changes in ph okay it's a it's a reason something that resists change in ph okay so if you accidentally spill a bunch of acid into a system and that system is not buffered okay you've just spilled acidity while the ph is going to plummet okay so the ph is going to go down very rapidly because it's not buffered if you instead of spilling into a unbuffered system let's say you spill it into a buffered system in this case because you have molecules that can serve to soak up that that acid it will change ph but not drastically it will only change ph a little bit okay and that's the benefit of a buffer okay ph will still change but on a much slower a much slower manner okay so buffers are very important they can resist um strong acids or they can resist strong bases okay it just depends on the type of buffer and you have different buff there's lots and lots of different buffers there are two really important ones that are in our blood that we will learn about um the presence of antacids are really buffers that are kind of counteracting the acidity of your stomach okay if you've heard of alkyl seltzer or tums or rollates these are basic compounds that are attempting they're essentially a weak base that's attempting to buffer out or tamp down or settle down it's an overactive stomach acid okay so when you eat something and your stomach is kind of going crazy you take an antacid anti-acid to mitigate that acidity okay because it's chemistry it works and it's very very useful all right so this is the only kind of scary graph that you'll see me present and this is a buffer curve okay so on the x-axis here we see the amount of hydrogen ion and then on the y-axis we have the ph level okay and so the red line here represents the activity of a buffer okay every buffering system has a pka that is this imagine that is the middle of this s-curve if you imagine this is kind of like an s-curve there's a steep portion and then a flat portion and then another steep portion in the very center of that s-curve is the pka okay it's the middle um ph where that buffer has equal potential to buffer against acids or to buffer against spaces okay we're not going to get into a lot of these the the mathematics about on pka because that's just not this course but in a chemistry course you'll have to know that if you go into biochem you will be memorizing pkas for lots of stuff okay all right all right so we have just kind of brought ourselves through inorganic chemistry okay there's a whole other section here that has to do with metals that we're not going to touch on because it's really irrelevant but we've talked about water some electrolytes or ions or salts we've talked about acid-base chemistry and buffers okay now we're going to finish off this chapter by talking about organic molecules okay organic molecules are characterized by having hydrocarbons okay hydrocarbons that is a c covalently bounded bonded to an h if you have one of these it's a organic molecule if you do not have this it is not so you could have co2 carbon dioxide right you've probably seen this before co2 and people say oh look there's a carbon it must be organic no okay there is definitely a carbon there but there are no bonds to a hydrogen and therefore it is considered an inorganic molecule okay it's actually a waste product of our metabolic processes okay so you need hydrocarbon bonds okay for it to be considered okay there are four classes of organic molecules um as you see here carbohydrates lipids proteins and nucleic acids you have to just memorize those four classes and we're going to go into each of them in a little detail not a lot of detail okay not as much as you would get in a biochemistry course okay they uh all these organic molecules um serve they function as polymers okay polymer is a long chain of covalently bounded bonded uh molecules okay so think about pearls on a string that works for you you have a monomer means a single subunit and a polymer means multiple of those subunits covalently bonded to each other okay so proteins act that way sugars act that way nucleic acids act that way lipids are the odd man out lipids do not form polymers strictly speaking okay they do form bilayers they form membranes and they form micelles that is lipids like to also kind of group together in a very unique way but they don't form polymers okay so only let's say carbs proteins and nucleic acids these are the ones that form polymers okay lipids do not and that's because of the unique hydrophobic nature of lipids now i wrote on the board so i gotta wipe it off here just give me a second all right now you might have noticed here i've kind of listed some of these major top major concepts we talked about matter and energy we talked about oil and water okay hydrophilics versus hydrophobic and this the last major con concept that is underlying all of the things that we're going to go on to talk about with carbohydrates proteins and lipids and such is redox reactions okay reduction oxidation and that's a whole other core you know you need to go to chemistry class to really appreciate that but that's the the chemical transformations that are underlying the exchange of matter matter energy okay redox reactions are the reason why we get energy out of matter okay out of fuels okay our ability to transfer electrons okay remember leo goes gur okay leo is uh loss of electrons that's oxidation and ger ger is gain of electrons that's reduction okay glucose and oxygen are these two um important components that we need to take into our body we eat food which is a source of glucose or sugar okay and we breathe oxygen and during cellular respiration there is an exchange of electrons between oxygen and glucose that's at the basis of all metabolism an exchange of electrons something's being oxidized and the other thing is being reduced we're not going to go into the reasons for that but if you can remember redox runs all of metabolism that will help you understand stuff all right so let's start talking about our first category remember there's four cat classes of organic molecules carbohydrates proteins lipids and nucleic acids okay we might not go in that precise order i might have mixed them up but those are the four classes firstly carbohydrates okay and the name here is is pretty um descriptive okay you have carbon that is hydrated and so just as i said before that our definition of an organic molecule is high hydrated okay not hydrated as in water but a carbon that has a hydrogen attached to it okay so it's a hydrocarbon so carbohydrate and in fact it is somewhat of a hydrated carbon because it follows the so if you look at glucose c6h12o6 this is the chemical equation for glucose if you break that down you actually have one carbon and you have water okay if you follow the ratios 6 12 6 same as 1 2 1. so it's actually a hydrate of carbon carbohydrate isn't that wonderful really easy okay so organic molecules that contain hnc and usually oxygen not always but usually they're covalently bonded okay that's important they are associated to each other by covalent bonds and that's the way the polymers are bound to each other they can contain functional groups that determine chemistry and we'll go into those first of all carbohydrates all right so these are important functional groups that you'll have to memorize as i reference them you'll just have to know what i'm talking about these are the four that you need to know an amine group has a nitrogen in there there's usually two sometimes three h's attached to it and then it can be attached to the rest of the molecule that's an amine okay amine okay a carboxyl group or a carboxylic acid has a double bonded c to an o and then another o h okay that's a carboxyl group or a carboxylic acid if we remove this h it's a carboxyl it's been dissociated a hydroxyl group okay just an o h is a hydroxyl group if that were to be a free ion it would be a hydroxide okay this is a hydroxol if you had an ion it'd be a hydroxide hydroxyl just oh the basis of making an alcohol if you're into organic chemistry and then a phosphate a phosphate has a p in the middle okay a phosphorus but something that makes a phosphate is they're surrounded by oxygens okay one two three four oxygens usually two of them are having a full negative charge and therefore phosphates are a source of negative charge and this is the basis of why dna has a negatively charged background backbone because of the phosphates we'll get into that later okay functional groups that you need to know all right so carbohydrates okay sugar okay some of the sugars that you probably familiar with is like table sugars sucrose okay sucrose is this the table sugar that we're familiar with that's not glucose okay glucose has very little sweetness to it okay if you took a bunch of glucose and put it in your mouth it would be very mildly sweet okay sucrose is quite sweet so we put sucrose in our coffee or whatever okay monosaccharides so those so sugars like um galactose and glucose and ribose those are monosaccharides because there is one sugar okay saccharide in the latin means sweet okay so one sweet thing okay they are typically um contain three to seven carbons okay so if you're looking at a sugar and you're trying to figure out what type of sugar it is you'd have to count the number of carbons okay and there's anywhere from three to seven in a typical sugar okay the one that we know the most about we talk about is glucose it has six carbons okay but these are the popular ones glucose fructose galactose okay if we take two of these we've joined them with a covalent bond okay we have a disaccharide meaning two okay sucrose table sugar is really joining of glucose and um and two glucoses okay glucose um and galactose make lactose if you're lactose intolerant there's a special bond there that is not easy to break for some pop part of the population okay there's an alpha versus a beta glycosidic bond we're not going to get into that all that detail okay maltose is two glucoses sucrose is um glucose plus fructose okay glucose fructose eco sucrose polysaccharides poly means many many saccharides means you have a long chain of sugars okay this is really a storage form okay so we have a long polymer of sugars that's in its storage form it means it's not accessible because they're now involved in these covalent bonds and you really need them in their single form for them to be biochemically active or available okay so if we have lots of sugar that's entered our body our body will naturally start pushing some of it away into a warehouse as a polysaccharide okay the one that we use the most is called glycogen okay glycogen is a polysaccharide it is a a storage form of sugar i mean carb load if you're an athlete and you play on the football team and like thursday night you have a big like spaghetti dinner all that pasta you're carb loading okay you're actually shoving away glucose in the form of glycogen into your muscles and into your liver in the hopes that the next day when you play football or whatever sport okay you're gonna be breaking up that sugar and utilizing it okay one sugar at a time you're going to break down that polysaccharide into monosaccharides and then those will go through glycolysis and krebs cycle and oxidative phosphorylation and you'll get some atp and your muscles can go all right so um in animals the storage form is uh glycogen in uh plants the storage form is starch okay so if you eat potatoes or other starchy foods okay the storage molecule there is very similar to glycogen okay starch cellulose is another storage form but it is largely indigestible that is our bodies do not contain the enzymes to effectively break the bonds here these here contain a certain type of bond an alpha glycosidic bond and these contain beta bonds okay which is ironically the same as lactose so the reason why we have problems with lactose and we have problems with cellulose is because of the type of bond and our body does not sometimes does not contain those enzymes here's what the sugar looks like here is a straight chain sugar and straight chains can actually cyclize that is this does a nucleophilic attack of this carbon and he forms a cyclic form okay so if you see either of these they're both sugars one is just in a cyclized form one is in a linear form okay but both count as in this case glucose okay we would count how many carbons one two three four five six we count the oxygens we could count the um the hydrogens and we could figure out what's the pattern here of ohs and we can learn that this is in fact glucose and not galactose okay i'm not going to ask you that so don't worry about identifying sugars this is a space-filling model of the same molecule okay and so as i said before we in these organic molecules we have monomers okay like monosaccharides and if we go through a reaction to form a covalent linkage now we have a polymer or in this case a disaccharide okay so here's a molecule of glucose and here's a molecule of fructose okay now fructose has two extra ring carbons and that's why it looks a little bit different as a five ringed um cycle a cyclic form but there's still six carbons on there okay one two three four five six okay so if we join glucose and fructose you can see that there is an oh on the glucose and an h here on the fructose and we call this a dehydration synthesis because what are we doing to the water we're removing water and we remove water you get dehydrated okay so dehydration synthesis the product of removing the water is to synthesize a bond so you're forming what's called a glycolytic bond okay glycosidic bond and so that's the way that you have now joined the two monomers okay monosaccharides into a disaccharide and this is table sugar okay so when you would eat this if it binds to the right receptor in your taste buds and it says tastes sweet right the reverse reaction here if we have the bond we add water and maybe an enzyme to speed that up you can break them down okay and you can do individual things with glucose and fructose okay so disaccharides and monosaccharides will have different properties especially with with respect to taste but also with respect to biochemical reactions this is a picture at the storage form this is these are examples of glycogen okay each of these little round balls is a single sugar and there are straight chain bonds and there are side chain bonds okay and alpha 1 4 versus alpha 1 6 glycosidic bond again you'll learn about those later what's important for us in the human body is that when we need energy okay let's say we've eaten some food but it's been now a couple hours since our last meal okay there's no new food coming into the gi tract and therefore spilling into the bloodstream so what are we going to do okay all the rest of the food has been let's say pooped out well we still have a storage form in the liver or in the muscle and it's in this form to really get access to this storage form we need to alert some special enzymes that can break off individual glucose molecules from these long chains and so if you wake up okay wake up or activate the right types of enzymes well suddenly they will start breaking off and cleaving these bonds and that free glucose will spill into the bloodstream and now you have this storage form being utilized and those individual glucose molecules will then get pushed into the bloodstream and now you have plenty of sugar for the brain or the muscle or whatever okay so an important outworking of this is how metabolism is regulated okay and our endocrine hormones can either speed up or slow down um these enzymes the liver enzymes again that's kind of downstream application i'm kind of jumping ahead of the and this is just a table we talked about monodye and polysaccharides already all right lipids okay lipids are our second category of macromolecules okay or organic molecules and as i said before lipids are kind of the odd man out that is they have very different properties as uh compared to carbs proteins and nucleic acids okay they are the only ones that are have a slightly different chemistry they are hydrophobic okay they do not play well with water or an aqueous environment okay so they're mainly hydrophobic molecules such as fats oils and waxes mostly made of carbon and hydrogen atoms and they include these molecules here fatty acids ecosonoids glycerides steroids phospholipids and glycolipids those are all examples they're all qualify as lipids okay we're going to go through a couple of these very quickly and i will we will come back and refer to these concepts in subsequent chapters especially in amp2 so fatty acids okay fatty acids are long chains of hydrocarbons let's look at a picture because it's easier to show okay so here's a long chain hydrocarbon okay all you see is gray blue gray and blue green blue okay and the zigzag is just covalently bound carbons okay these are the same things one is a space filling model one is a line model okay so you can see there's a long chain of carbons and all the other available bonding sites because carbon has four available valence electrons therefore it can form four bonds well two of them are always involved in the straight chain and then two of them are available for hydrogen bonding okay i i mean that's that's not i just said something that's wrong okay not hydrogen bonding but bonding to hydrogen hydrogen bonding is something different okay intramolecular versus in intramolecular intermolecular anyway so this is a fatty acid chain okay it's basically carbon and every single other spot okay is saturated with hydrogen okay i'm going to say that again every other spot here is saturated with hydrogen there are no double bonds and there are no other molecules so that's actually a definition that you will hear about which is a saturated fatty acid okay and the result of this is to create a linear molecule okay it looks zigzaggy but we call this a linear molecule because it's straight it's called lauric acid it is has 12 carbons and on this side we have a carboxylic acid here's our double bond to oxygen and an o h and then this h because of the conjugation of electrons here can be go into solution okay so this is an acid it's a fatty acid so if we introduce a double bond notice these are all single carbon carbon double bonds it's a covalent bond if we introduce a double bond well we've desaturated okay we were saturated with oxygen now those available electrons are not saturated without with oxygen with hydrogen excuse me but now we're forming a double bond okay so we call this a mono unsaturated fatty acid okay mono meaning there's only one okay it's forming this double bond the result of this double bond is to create a kink or a bend in this otherwise straight molecule because we've placed a double bond here now it's bent okay it forms a bend in the molecule and that bend actually has some important consequences okay so here is a straight chain saturated fatty acid here is another straight chain fatty acid but here we have a double bond now as you learn in chemistry you could have either a cis double bond or a transitable bond and we're going into the weeds here a little bit um but this is the trans conformation and this is an assist okay so the cis has this bent conformation here okay and the trans does not so if you've heard about trans fats trans fats were are double bonds that have been forced to become um in the trans conformation so they're straight okay so they actually function even though they're a mono unsaturated fatty acid they function like a saturated so trans fats are not good for us they're pretty much as bad for us as saturated fats so here is just to kind of exaggerate the point that when we introduce a double bond okay we introduce this bend in the molecule now who cares okay the reason that this is meaningful is if you think about these molecules as bricks okay and what you need when you have bricks is that they stack on top of each other very flatly and uniformly and therefore you get this nice tight packing that occurs okay so this can form tight packing this cannot okay it's all jumbled and twisted and bent and it just does not form as tight of a packing molecule as this so saturated fats and actually trans fats okay have this straight or linear conformation they pack tightly and therefore they build up in your arteries okay so that's why these are bad because they type packly together pack tightly together and their physical characteristics reveal that so if you look at butter at room temperature what form is it in solid semi-solid okay or lard or crisco or any other hard fats okay animal fats are hard okay or they have some type of semi-solid at room temperature plant oils they are usually mono or polyunsaturated they're more oils they're more liquidy okay so olive oil and vegetable oil and lots of oils have more of this conformation and therefore because they can't pack tightly they have a more liquid form at room temperature okay so those are technically speaking slightly more healthy than the animal fats now coconut oil is unique right if any of you have worked with coconut oil it is also solid at room temperature if you melt it just a little bit it goes into it it melts but surprisingly it still has better properties than animal fats all right so this is what i just talked about here the way it looks on the tabletop at room temperature could give you a good indication of whether it is saturated fatty acids or it is unsaturated okay vegetable oils lots of unsaturated okay shortening crisco lard those are highly saturated okay they're solid like butter okay or margarine um at room temperature and therefore because they have this tendency to form these tightly packed clumps it builds up in our arteries okay and it can it can accumulate and that causes all kinds of problems in the cardiovascular system all right so those are fatty acids and things like triglycerides e-carcinoids are derived from the fatty acid called arachidonic acid we have two groups here leukotrienes and prostaglandins we will briefly mention prostaglandins when it comes to the nervous system and our sensation of pain and inflammation okay this is really involved in an inflammatory response and the way that we mitigate pain and inflammation is through nsaids okay non-steroidal anti-inflammatory drugs okay nsaid so nsaids target prostaglandins actually the prostaglandins kind of pathway okay so prostaglandin is a lipid and it's involved in pain and inflammation okay um this is um arachidonic acid okay so it is important for the uh the formation of other lipids i'm not going to ask you about this i'm going to skip over it for now okay glycerides are where we take our fatty acids and we attach them to a glycerol okay let's look at a picture okay so here is our fatty acids we've just looked at a bunch of those if we form a covalent bond with a glycerol molecule here shown in purple we form a tri glycerol okay sorry triglyceride okay so triglycerides are a three carbon backbone one two three and attached to them are three fatty acids okay this is called a triglyceride so this is the for the storage form of most of our fats if you have adipose tissue or fat tissue around our body visceral fat or subcutaneous fat this is the form that you will see in those fat vacuoles here of adipose so again there's some chemistry here to form the bond or break the bond but this is the storage form for most of our fats all right we also have steroids in the form of cholesterol cholesterol is the precursor and from cholesterol we can make important things like sex steroids as well as other hormone hormone sex hormones i'm just going to reference them this is another class of lipids okay here's cholesterol steroids cholesterols have this classic four ring presentation okay four ring structure one two three four and there's four rings and they typically have this similar arrangement okay here on the left is estrogen beta 17 beta ester dial and testosterone okay these are the molecules that play huge roles in puberty and sexual differentiation okay both of these molecules are derivative of cholesterol okay so this is the starting place there's a couple steps that lead you in this direction or a couple steps that lead you in this direction phospholipids okay very very important class subclass in within lipids okay phospholipids and glycolipids very important for membranes okay so here's our glycerol background backbone okay we talked about triglycerides the glycerol is always the same as three carbons one two three instead of having three fatty acids the third position instead of another fatty acid now we have this special head group okay and so it's a phosphate with usually some other modification at the top okay so this is a glycerol phospholipid or just called a phospholipid so this tail portion here is hydrophobic water fearing and this top portion because of this phosphate remember that phosphates have negative charge and therefore it's attracting other polar molecules like water so this top portion is water loving hydrophilic and this bottom portion is hydrophobic water fury therefore this molecule is key in establishing the lipid bilayer which is the membranes in our cells there's other ways of forming a similar type of molecule this is a glycolipid okay so instead of having a phosphate group here we just have a sugar or a carbohydrate okay that's the same background backbone of glycerol one two three carbons two fatty acid chains which could have any number of carbons in there but the third position has some other functional group okay so here's phospholipids and when we look at them in diagram we'll just make that whole top portion a ball and we'll have the two chains hanging down into this tail okay the tail like appearance they can form micelles or they can form um phospholipid bilayers or membranes okay i'm going to skip over this for now this is how basically how you make soap is you take glycerol you add strong base and you can make soap okay if you've ever done like a crafty etsy thing and you made like fancy soap this is the the chemistry here i'm not going to ask you about it it's just kind of an interesting thing the basis of soap i just the point that i want to make here is we have a sodium associated with this carboxylic acid and the long fatty acid chain and that's really the function of soap is to have one portion here that is hydrophobic and one portion here which is hydrophilic and that is critical for soap because when you want to have water release dirt and grime and soil from your clothing or even from your hands we need to interface with the oils and the dirt and the grime and soap turns out to have both of these properties it's called it has the property of being um aliphatic okay or amphipathic or amphiphilic amphi means a little of both has some hydrophobicity and some hydrophilicity okay so soap can form these micelles and so this oil particle or piece of dirt or piece of grime that is needs to be removed from your clothing or removed from your skin gets surrounded by these fatty acid chains notice the balls here are facing outward so it's interacting with water but the inward tails are pointing towards the oily or the dirt molecule okay which tends to be hydrophobic okay so we've now added soap to our dirty laundry or dishes or our hands and it helps us to remove them from from our skin or our laundry all right i'm over time by a couple minutes i apologize for that next up is protein the that will be the next uh next video will be the last video in this chapter see you guys in class