Chapter 1- Chemistry Part 2 (Macromolecules)

so in this lecture we're going to talk about chemistry and specifically look at macromolecules and so we're going to start this lecture talking about carbon and why carbon is so essential to life so if you recall that the cell is primarily water about 70 to 95 percent of the cell volume is composed of water and the rest is carbon-based compounds and this would include our macromolecules which are carbon based compounds which are organic molecules and in these types of molecules you'll see carbon bound to other carbon atoms carbon bound to other elements such as hydrogen

oxygen nitrogen sulfur and phosphorus and so we'll look at the examples of our carbon-based compounds specifically looking at our carbohydrates lipids proteins and nucleic acids such as DNA and RNA so we're gonna start by talking about why carbon is central to life and you might recall that carbon has an atomic number of 6 so if carbon has an atomic number of 6 how many protons does carbon have and recall that the number of protons is equal to the atomic number so carbon has 6 protons which are positively charged which means how many electrons would carbon

have the answer is 6 so it has 2 electrons in the first shell and 4 in the second shell that brings us to 6 how many more electrons does carbon need to fill its outer shell and the answer is 4 so carbon will need 4 more so because of the fact that carbon has four valence electrons and it needs four more carbon will make four covalent bonds so we have one covalent bond two covalent bonds three and four and that will help carbon to fill its outer shell and so carbon has a great bonding capacity

due to its structure because it's able to form a maximum of four covalent bonds and recall that covalent bonds are stable and so this forms these strong stable covalent bonds including other carbon atoms as well as other atoms like hydrogen and oxygen so when we look at our hydrocarbons hydrocarbons are going to be made of carbon and hydrogen and remember that carbon and hydrogen have similar electronegativities and that's because they're both half full so carbon has four valence electrons it needs four more hydrogen has one valence electron it needs one more and so in terms

of their electronegativities carbon and hydrogen have similar electronegativities and because they have similar electronegativities recall that when they share electrons when they form a covalent bond they're going to share their electrons equally neither one is gonna pull harder for those electrons remember that this will be a nonpolar covalent bond nonpolar remember think of non pulling neither atom has a greater electronegativity and therefore they share those electrons equally now if these molecules are nonpolar they are also hydrophobic because remember hydrophobic means water fearing and in order for things to be hydrophilic water-loving they have to have

some sort of charge whether that be a partial charge in a polar molecule or a full charge in an ionic molecule in an ion either way a charge is what allows something to interact with water if we're talking about a molecule that's nonpolar there are no charges because those electrons are evenly distributed and so there's not going to be one part of the molecule that's partially negative and one part that's partially positive there's no charge overall on the molecule and as a result those molecules can't interact with water and that's why these are considered to

be hydrophobic now when we look at hydrocarbons they can exist in many different forms they could be linear chains like is the case for ethane or propane they could be branched chains if you look here at isobutane or two methyl propane that's branch so you have your carbon skeleton and then a carbon branching from there you could have ring structures so we have cyclohexane we have benzene these are different type of carbon-based rings we could have very short chains meaning two carbons long and like it's like for ethane or they could be several or 20s

30s however long chains so long hydrocarbons carbon can form single bonds meaning it shares one pair of electrons which is indicated by a single line carbon can form double bonds which you can see here is two lines that means it's sharing two pairs of electrons and in some cases carbon even exists in triple bonds meaning that they can share three pairs of electrons and so carbon is basically has a variety of different structures that can form because of its high bonding capacity and so hydro carbons are primary components of fats and fossil fuels now because

carbon can exist in many forms different compounds with the same molecular formula can be produced and these structures we call isomers and so what I mean by that is I'll give you an example if we look at a theme and propane ethane is going to be c2 there's two carbons and if we count the number of hydrogens one two three four five six it would be H six propane on the other hand is c3h8 and so we would say that ethane propane are not isomers they don't have the same molecular formula if we were saying

that they were isomers they would both be for example c2h6 so what I want you to do is to look at the next pair so we have butane and we have isobutane and I want you to think about and just look at these molecules for a moment and tell me are these two molecules isomers then look at 1-butene and 2-butene are these two molecules isomers look at the ring structures the cyclohexane in the benzene are those isomers so go ahead and pause and think about your answer for a minute and then when you're ready go

ahead and turn it back on and we'll talk about which of these pairs are isomers so if we look at butane butane is c4h10 if we look at isobutane it is also c4h10 so knowing that is butane and isobutane are those isomers yes these are both isomers they both have the same molecular formula they're both c4h10 yet they are isomers because they have different structures and so notice that carbon is able to form these isomers we can have the same molecular formula but slightly different structures if we look at 1 butene and 2 butene both

of these are c4h8 c4h8 so would we say that 1 butene and 2 butene are isomers answer is yes the only difference between 1 butene and 2 butene is the position of this double bond so in 1 butene it's on the first car on 2-butene it's on the second carbon and so these two molecules would be considered isomers now let's look at cyclohexane cyclohexene notice has c6 and if we look at the hydrogen's we have one two three four five six seven eight nine ten eleven twelve and if we look at benzene we have c6

but h6 also because these double bonds make it so that there are less hydrogens on each carbon because remember carbon forms a maximum of four bonds so one two three and four carbon is full this carbon one two three four that is full and so you'll often see these carbon-based molecules simplified so that when you look at this ring like for cyclohexane each of these points represents a carbon and the reason that they can simplify this is because if you know that carbon forms four bonds they don't need to draw the hydrogen's on here because

anybody knows that carbon has to have four bonds which means that if we have carbon with this bond and this bond it has to have two hydrogen's to make its number of bonds before if we look at this carbon right we know it has one two and three which means that it only has one hydrogen coming off and so you'll often see these ring structures being simplified because you don't need to specify how many hydrogens are on there you don't have to actually draw them out so cyclohexane and benzene are those isomers and the answer

is no they both are six carbon rings but the number of hydrogen's is not equivalent cyclohexene has 12 hydrogens while benzene has so the chain of carbon atoms in an organic molecule is referred to as its carbon skeleton and then coming off of the carbon skeleton we can have varying what we call functional groups so a functional group is a group of atoms that confer a special biological property on a carbon-based molecule and these functional groups affect about biological molecules function in a characteristic way for example if we look at a theme methane is going

to be a two carbon molecule ethane is a gas if we replace one of those hydrogen's with something called a hydroxyl group which is basically an OS group that hydroxyl group now makes that molecule be an alcohol and so now we've gone from ethane to ethanol which is drinking alcohol so by simply adding that oxygen to that carbon based molecule we went from ethane which is a gas to ethanol which is going to be a liquid and so this functional group this hydroxyl group basically gives this carbon-based molecule a characteristic property it makes it become

an alcohol and so organic compounds have unique properties that depend on the size and the shape of the molecule and the groups of atoms or functional groups that are attached to it so this slide is just showing you the importance of functional groups so what you're looking at is on the Left estradiol which is the precursor for estrogen and on the right is testosterone and estrogen is the female hormone and testosterone is the male hormone and notice that they're both sterile hormones or steroid hormones which means that they're made of four fused rings and attached

to those four fused rings have various functional groups and so notice that they're highlighted in blue so for testosterone it has the ch3 group with what's called a methyl group and estradiol does not have that methyl group the other difference is going to be at this position estradiol has a hydrogen whereas here instead the oxygen is double bound to a carbon what's called a carbonyl group and so notice what it makes testosterone an estrogen different from one another is simply two functional groups it's the methyl group and then it's either a carbonyl group versus a

what we call hydroxyl group and so the only difference between essentially being male and female comes down to simply these two functional groups so we're gonna talk about some of the names of certain functional groups and the ones that you need to know and the first is what's called a hydroxyl group and this hydroxyl group is gonna be so the AR represents a carbon skeleton and attached to that carbon skeleton is an oxygen and a hydrogen that again together is referred to as a hydroxyl group having hydroxyl groups on molecules makes those molecules and alcohol

and so some examples of molecules that contain these hydroxyl groups certain lipids will have them as well as carbohydrates which are going to be your sugars so glucose for example has hydroxyl groups all over it the next group collectively these two I referred to as a carbonyl group and let me erase this last part here carbon eel and in a carbonyl group it's going to be a carbon that's attached to a carbon skeleton and then that carbon is double bound to an oxygen now if that carbon double bound to an oxygen is at the end

of a molecule it's referred to as an aldehyde and the way I remember that is aldehyde begins with a vowel and begins with a vowel so aldehydes are on the end on the flip side if you're looking at a carbon double bound to oxygen that's in the middle not at the end but in the middle of a carbon skeleton we call that a ketone so think of K&M ketones are in the middle and so these carbonyl groups are used for example in sugars like glucose fructose has carbonyl groups etc the next functional group is what

we call a methyl group and a methyl group is a ch3 group it's a carbon bound to three hydrogen's and methyl groups are used in DNA so it's used to mark DNA and it affects what we call gene expression which we'll talk about later on in the semester it's also important for energy metabolism next we have our amino groups and our amino groups is gonna be a nitrogen bound to two hydrogen's and so amino groups are going to be important for proteins for example we are gonna learn that the building blocks of proteins are referred

to as amino acids so the building blocks are amino acids the reason they're called amino acids the amino part comes from the fact that that building block has an amino functional group these two the ester and the ether you don't need to know these for the exam an ester linkage is going to be found in the cell membrane or the plasma membrane of bacterial and eukaryotic cells ether linked lipids are going to be found in our Kail plasma membranes and so that's a difference in terms of their function for where they're found sulf hydro groups

which is going to be a sulfur bound to a hydrogen that you do need to know and what we're going to learn in the class is that these sulfide ro groups serve several purposes one is their use for energy metabolism meaning that they can be used as a source of sulfur as well as a source of energy salt hydro groups are also important for protein structure because what we're going to learn is that proteins only function if they're in their correct conformation and in order for proteins to be in their correct conformation or shape the

protein or the amino acids need to interact with one another the amino acid can interact using hydrogen bonding ionic bonding covalent bonding etc and if it's gonna interact using covalent bonding between amino acids it's gonna link through so these sulfhydryl groups meaning these two sulfhydryl groups can link together and it can form a covalent bond and that covalent bond is very strong and sturdy and helps give protein strength and structure the next group that we're going to talk about is gonna be the carboxyl group and the carboxyl group is going to be AC double bound

oh and this carbon is also bound to another oxygen and so that's the difference between a carboxyl and a carbonyl group carboxyl group is a carbon bound to two oxygens now the interesting things about these carboxyl groups is that this oxygen and carbon form and double bond and what can happen is that this double bond does something called resonance meaning the electron can come and now the carbon can be sharing the electrons with this oxygen and so when this electron is being shared here what that does is that causes hydrogen to leave because oxygen remember

can only form two bonds so if the electron is shared over between this carbon and this oxygen that will cause that hydrogen to leave and therefore these carboxyl groups act as acids meaning that they will add or donate hydrogens to the solution because when that double bond resonates its gonna kick off that hydrogen it's gonna increase the hydrogen ion concentration of the solution and so this is gonna be found in organic acids you'll find these in lipids proteins also have carboxyl groups for example again the building blocks of proteins are referred to as amino acids

amino comes from the fact that it has that amino functional group acids come from the fact that it has this carboxyl group which acts as an acid and that's why they're called amino acids the last functional group that we need to know is gonna be our phosphate group and our phosphate phosphate group is going to be a phosphorus bound to four oxygen and so notice that these phosphate groups give molecules an net negative charge and so we're you're gonna see phosphate groups would be nucleic acids like adenosine triphosphate so ATP which is used for energy

we have phosphates in DNA for example as well as lipids lipids are made up of our type of lipid is going to be a phospholipid and a phospholipid is the primary component of the cell membrane and remember the selves have a overall negative charge and remember that's why they stain with a basic stain which is positively charged and so that negative charge partly comes from having these phosphate groups on the phospholipids on the cell membrane so what I want you to do now is to test your knowledge and see if you can identify the functional

groups in an amino acid and so in an amino acid we have the central carbon down to a hydrogen down to an R group which is the variable part of the amino acid and so what I want you to do is to identify this region and the blue and this region that's kind of this reddish pink color and so go ahead and identify those pause the video while you try and work on this and when you're ready go ahead and turn it back on so if you said that the blue is an amino group and

the red is a carboxyl group then you would be correct and again it's because this is the amino and the acid comes from the fact that this carboxyl group can donate hydrogen's to the solution and therefore act as an acid so question for you carbon is such an important molecule for life because red it can be bonded ionically yellow it cannot form isomers green it can form chemical bonds with the maximum of four of their atoms blue it can hydrogen bond to so many molecules purple it's part of the water molecule so go ahead and

pause think about your answer and when you're ready go ahead and turn back on your video to hear the correct answer so if you said green then you're correct it can form chemical bonds with a maximum of four other atoms so remember that carbon has four valence electrons it needs four more to fill its outer shell and therefore will form four covalent bonds it's not red it can be bonded ionic Li because remember that an ion has a different number of electrons now in order for carbon to be an ion remember that carbon has four

valence electrons so to fill its outer shell carbon would either need to donate all four electrons or receive four electrons and that's not likely to happen right carbon is not highly electronegative therefore will not be able to attract four electrons or steal four electrons from other atoms so carbon is not typically gonna form ionic bonds yellow it cannot form isomers that's not true right we saw examples of isomers butane isobutane 1 butene 2 butene those are both examples of isomers they have the same molecular formula but slightly different structures so it's not yellow blue says

it can hydrogen bond to so many molecules that is not true remember that the definition of a hydrogen bond is an already covalently linked hydrogen to an electronegative atom carbon is not an electronegative atom it has very little electronegativity and therefore it doesn't form hydrogen bonds purple it's part of the water molecule that is not true right water is simply h2o which is two hydrogen's and an oxygen so now we're going to go through and talk about our carbon-based macromolecules so what are macromolecules these are simply large molecules that are important for life and so

of the four classes of macromolecules proteins carbohydrates and nucleic acids all exists as what we call polymers poly means many meaning it's many repeating subunits linked together by covalent bonds and so notice it says chains of simple monomers mono means one so it's one subunit that's linked together by a covalent bond and so these three macromolecules have a single type of subunit and the subunit repeats over and over again and you get these polymers lipids on the other hand which is our fourth class of macromolecule do not exist as polymers they don't have one repeating

subunit these lipids are built from two or more different types of smaller subunits so for example you're gonna see when we look at lipids we have our steroids for example we have our triglycerides structurally they're very different there's not one repeating subunit that's found in lipids so again monomer mono means one it's a single building block that can be linked up to form a polymer and poly means many so it's many repeating subunits similar types at least linked together and polymers can be thousands of monomers long so an example of a monomer would be a

monosaccharide mono means one saccharide of sugar it's one simple sugar so for example glucose glucose would be an example of a monomer the polymer of glucose is called a polysaccharide meaning many sugars linked together and an example of a polysaccharide would be starch so whenever we're building our polymers we are going to use a dehydration reaction think about if you become dehydrated what has happened that means that you've lost water right water was removed and so in a dehydration reaction that means that we start with this growing chain or this short polymer and a monomer

that we're trying to link on to this polymer and so what's gonna happen is is that what's what you're gonna see is that we need to remove water in order to form the covalent bond between that growing polymer and that unlinked monomer and so water's gonna be removed and now we're gonna form a bond between those two molecules and so now my polymer has grown by one additional monomer and so this will remove water to form these polymers now I want you to think for a minute what do you think would have to happen if

we want to break that bond right so if we had to remove water to form that bond what do you think has to happen in order for that bond to be broken and if you said that water would need to be added back you would be correct and so water gets added back to break that bond and that's referred to as hydrolysis hydro water lysis breaking so hydrolysis is using water to break that bond and so we've looked at several hydrolysis reaction so far in lab right we looked at starch hydrolysis for example and that

is we were looking at the breakdown of starch removing glucose from that molecule of starch and so that's hydrolysis we have to put in water in order to break that bond and so building polymers dehydration breaking them down is gonna be hydrolysis so if we look at examples of monomers and polymers the first class of macromolecule will be the carbohydrate and when looking at a carbohydrate the type or the name of the of the monomer is gonna be a mono saccharide mono means one saccharide is sugar it's one sugar an example would be glucose or

fructose now be careful if I ask you the name of the monomer for carbohydrates you're not going to say the name of the monomer is glucose glucose is an example but the name of the monomer for a carbohydrate is going to be a monosaccharide the polymer of a carbohydrate is referred to as a polysaccharide it's many sugars linked together and we will talk about some examples we'll look at starch and glycogen and cellulose etc those are examples of polysaccharides if we're talking about our macro molecules being proteins our monomer is gonna be our amino acid

that's the building block of proteins examples arginine leucine in lab we looked at tryptophan for our indole test right those are amino acids the polymer is referred to as either a polypeptide or a protein now polypeptide that's many amino acids linked together the difference between a polypeptide and a protein is a protein is more of this three-dimensional structure at the end meaning that a protein might be made of multiple polypeptide chains for example hemoglobin is a type of protein hemoglobin is made of four separate polypeptide chains two alpha subunits and two beta subunits and so

it's four polypeptide chains put together to form the functional protein and so if I were to ask you what the polymer is for protein you would be correct if you said either a polypeptide or a protein lastly we have our nucleic acids and our monomer for nucleic acids would be our nucleotide and a nucleotide is made of three parts a sugar a phosphate and a nitrogenous base if we linked nucleotides together the polymer that we're going to get is going to be a nucleic acid and so an example of a nucleic acid would be DNA

or RNA now notice we're missing a class of macromolecule on this list you might notice that we don't have lipids here on this table and recall back to what we talked about why wouldn't we see lipids on this table and the answer is that lipids don't have monomers and polymers there's not one repeating subunit that's linked together to make up a polymer for lipids so a polymer is read a small molecule such as glucose yellow an element that forms two or more bonds green an animal that eats more than one type of food blue large

molecule made of many similar subunits purple large molecule made up of different types of subunits so go ahead and pause think about your answer and when you're ready go ahead and turn the video back on to hear the correct answer so if you said blue you would be correct it's large molecule made of many similar subunits now notice that I was careful not to use same and the reason is is that they will be of the same type but they don't necessarily have to be exactly the same what I mean by that is if we

look at our protein which is our polymer proteins are amino acids that are linked together it could be leucine linked with our gene linked with methionine glycine alanine etc they're all amino acids but they're not necessarily the same amino acid and so that's why I was careful not to say the same but similar subunits they're the same type but they might not be identical purples not true because it says a large molecule made of different types of subunits that's not true they're not different types they're similar types so it's not different types similar types linked

together so we're gonna look at now our types of macromolecules and the first one we'll talk about will be our carbohydrates so the first macro molecule would be our carbohydrates and the main function of carbohydrates is that they're used for cell structure for example cellulose makes up the cell wall of plants that means that this carbohydrate is used for the structure in the cell carbohydrates are also a primary energy source meaning that organisms organisms use them as a food source the atoms that you will find in a carbohydrate will be carbon hydrogen and oxygen with

the formula C h2o n referring to like the number of carbons so let's say we're talking about a six carbon sugar it would have a molecular formula of c6 h-12 o-6 so there would be twice as many hydrogen's as there would be for carbon or oxygen the monomers of a carbohydrate are referred to as a monosaccharide and so these are simple sugars with lengths of between three to seven carbons now when you think of carbohydrates probably the most common things that come to mind would be really starchy foods bread pasta crackers etc but it's important

to note that these are not the only foods that contain carbohydrates milk has a carbohydrate it has lactose in it the fruit has carbohydrates in it it has fructose in it etc so while these are examples of foods that are rich in carbohydrates these are not the only examples so our building blocks of our sugars are referred to as our monosaccharides and so again these are going to be our simple sugars these cannot be broken down into smaller sugars they simply are the smallest subunit and monosaccharides serve as the main fuel molecule for cellular work

meaning glucose for example is a primary energy source for most cells fructose on the other hand fructose would be fruit sugar so bananas oranges apples would all contain fructose which is a monosaccharide disaccharide dye means two this is a double sugar meaning that it's two linked monosaccharides it could be sucrose which is table sugar that is glucose and fructose linked together it could be lactose which is milk sugar that's glucose and galactose linked together it could be maltose which is two glucose molecules linked together etc etc so you get different disaccharides depending on which monosaccharides

you link together so as an example to show you the difference between our monosaccharides so notice that the picture on the Left we have glucose glucose is c6h12o6 on the right we have fructose which is c6h12o6 and so these two molecules are isomers they have the same molecular formula yet structurally they're different if we look at fructose fructose has the carbonyl group in the middle which makes it a ketone glucose on the other hand has that functional group that carbonyl group at the end which makes it an aldehyde and so simply by switching the position

of that carbonyl group excuse me it affects the function of that molecule fructose is a lot sweeter considerably sweeter than glucose if you've ever had to take a glucose tolerance test for example to test for diabetes etc you'll know that drinking that glucose solution doesn't taste good it's not what you think of as like a sugary drink it has a very different taste and so even though glucose and fructose have the same molecular formula structurally they're different which makes them behave in very different ways so if we are going to link our monosaccharides together we

need to do a dehydration reaction and so remember that to link or to form polymers we need dehydration reactions so we are going to remove a molecule of water in order to covalently link those two sugars together and so the type of bond that forms as a result is referred to as a glycosidic linkage glyco referring to sugar so this is going to form a glycosidic linkage that will join glucose plus galactose together and that now is going to be our disaccharide and so again lactose would be our milk sugar so our polymer of carbohydrates

are referred to as a polysaccharide meaning many sugars linked together and these are also referred to as our complex carbohydrates there are four different polysaccharides that are critical in the living world starch and glycogen these are both storage polysaccharide meaning that this is how organism store their sugar for energy cellulose and chitin are both structural they are used to give organism cells structure and strength and so that's different than starch and glycogen which is used for energy so starch is the nutrient storage form of carbohydrates and plants this is how plants store their sugar for

example plants would store sugar so that during this during the winter when sunlight is not available and the plant can't continue to do photosynthesis instead of making more sugar it's going to utilize its stored sugar in order to still have a food source even when sunlight is not available so an example of places where you might find starch seeds for example rice wheat grains these are all places where starch would be stored in the roots of certain plants so carrots and beets would store would store starch in the roots potatoes etc glycogen is the nutrient

storage form of carbohydrates in animals this is how animals store their sugar we don't store it as we don't start a starch instead we store it as glycogen and for animals glycogen is stored in two tissues primarily it's used or stored in muscles or liver cells and when this when the body requires glucose let's say for example you haven't eaten for a while your cells still need glucose in order to do cellular respiration and to make ATP and so in that case if you haven't eaten in a while and your cells are utilizing your blood

sugar now your blood sugar will begin to drop so your blood sugar levels will drop and yourself still need sugar for energy and so what the body's gonna do is now it's gonna break down that stored sugar it's going to break down the glycogen in the liver or the muscle and it's gonna take that that glycogen and break it down and release glucose and that will help blood glucose levels to go back up and so basically glycogen is storage sugar for animals cellulose remember is a structural carbohydrate it's a rigid structural carbohydrate found in the

cell walls of many organisms for example plants or algae this is the most abundant organic compound on earth trees cotton leaves cellulose or grasses are made largely of cellulose now humans and other mammals can't digest cellulose meaning that we can't break it down to use that sugar as energy however in the gut of certain animals like cows for example they will have some by ants or these organisms like bacteria that work together with the cow and will help them to digest the cellulose in the grass that they eat for example now cellulose work is a

type of complex carbohydrate and although we can't break it down for food meaning for energy it doesn't mean that we shouldn't eat foods that have cellulose in them because while cellulose is not used for energy per se it's a major source of insoluble fiber meaning that our bodies don't break it down and it helps us to feel full longer which helps us to not overeat it also helps us to move our food through our digestive tract because this gross as the sounds one of the things that happens when we eat fiber is that the gut

will start to produce a mucusy substance and that mucous that is produced will help to move the food through the digestive tract and so if you've ever heard of somebody being constipated a doctor will say you know you should try eating a high-fiber diet right because that fiber is gonna help to basically stimulate that mucus which will help to move food through the digestive tract our last complex carbohydrate is going to be chitin and this is a tough carbohydrate that forms the external skeleton of arthropods it's also found in the cell walls of fungi and

again our bodies ourselves can't digest chitin but chitin is used to give shape and strength to the structure of the organism and so we're gonna move on now to talk about our lipids so lipids there are three general classes we have our triglycerides our triglycerides our otherwise known as our fats we have our phospholipids which will be our membrane lipids we have our sterols which you can see in the bottom left here these are gonna be our cholesterol x' and our steroid hormones like estrogen testosterone etc they're made of four fused rings but notice that

if you look at the sterile and compare it excuse me with the fat and you compare that with the phospholipid that structurally they're very very different right they don't have one repeating subunits and remember we said that lipids don't have these monomers and polymers but what you will notice is that one of the things that happens in lipids is they are primarily hydrocarbons meaning they're made primarily of carbon and hydrogen not only carbon hydrogen but mostly now if you recall carbon and hydrogen have similar electronegativities right so carbon and hydrogen have similar electronegativities which means

that when they share electrons will they share equally or unequally and the answer is that they will share equally right neither one is going to pull harder for those electrons so as a result because they're sharing equally will that be polar or nonpolar and the answer is nonpolar which remember think of non pulling neither atom is pulling harder for those electrons and as a result if the electrons are shared equally and they're nonpolar do we end up with the charge on these hydrocarbons and the answer is no there's no charge so would that then be

hydrophobic or hydrophilic so if you said hydrophobic you would be correct they would be water fearing meaning they don't interact with water because there's no charge on that lipid in order for it to interact with the water and so this is why for example oil and water don't mix because it's largely hydrophobic it's primarily hydrocarbon carbon and hydrogen similar electronegativities because of their similar electronegativities they're gonna share electrons equally which means that they're going to be nonpolar when they're nonpolar they're not gonna have a charge and therefore they will be hydrophobic and so what makes

something classified as a lipid is that it's primarily hydrocarbons it's nonpolar and its hydrophobic otherwise in terms of structure they're very different so a triglyceride tri means three it's one glycerol which is a three carbon sugar so this is our 3 carbon sugar with our hydroxyl groups on it we are gonna link this one glycerol to 3 fatty acid chains and so these fatty acids basically are going to be these largely hydrocarbon groups with a carboxyl group on them and so to form our triglyceride we are gonna do a dehydration reaction because remember that for

anytime we're building something we're gonna use dehydration and we're gonna remove water so we're going to remove a water here water molecule here another one here and the type of bond that's gonna form between them is going to be called an ester linkage and so the ester linkage is going to be linking the glycerol with the fatty acid chains when we look at those fatty acid chains the fatty acid chains could be the same meaning it could be that they are made of all palma de casa de for example or it's possible that the fatty

acid chains on the triglyceride are different so it could be partly one type and then partly another etc and so those fatty acid chains can vary so when we look at our triglycerides our fatty acid chains can be saturated fats and what that means is that when we say that a fat is a saturated fat recall that when you see these little points these represent carbons and that we don't see the hydrogen's on there because we know that depending on how many how many bonds carbon can form right carbon forms for that we know how

many hydrogen's will be coming off of it and so if we look at a hydrocarbon chain which is many carbons linked together we know that so here's the rest here's our hydrogen and our hedging etc and then this last carbon has three hydrogen's to form it's four bonds and so if we say that a fatty acid is saturated it means that it's saturated with hydrogens it has the most number of hydrogens that it can possibly have and that happens when carbon forms all single bonds between the carbon atoms notice what happens if I add a

double bond here so if that double bond is there right remember that carbon only forms four bonds so 1 2 3 4 this hydrogen goes away this hydrogen goes away so when we add a double bond it's no longer saturated with hydrogen's it's missing some of those hydrogen's and therefore we would then call that an unsaturated fat so the difference between a saturated fat and an unsaturated saturated fat has all carbon single bonds and therefore is going to be saturated with their hydrogens when this happens carbon forms these straight linear molecules meaning that there's no

kinks or bends in this hydrocarbon chain and so as a result you can imagine that if these fatty acid chains represent papers like if you had a stack of papers that are all flat they would stack tightly on top of one another and therefore because they could pack in tightly saturated fats are typically solid at room temperature and so they're solid because these fatty acids can can stack very tightly and therefore they're more likely to be solid at room temperature saturated fats are more commonly associated with fats coming from animal products etc unsaturated fats remember

are when we have our double bond and therefore the molecule is not saturated oops let's not put that one there the molecule is not saturated with the hydrogen's anymore because when we have a double bond that basically makes it so that hydrogen has to be removed because carbon can only form a maximum of four bonds and so if you've ever heard of a mono unsaturated fat what that simply means is that that fat has one double bond a polyunsaturated fat on the other hand has more than one double bond to three etc and so our

unsaturated fats have at least one carbon-carbon double bond the molecule is not saturated with hydrogens and what ends up happening is is wherever that double bond is that can cause a kink in the molecule so now you can imagine that if you don't have flat papers but instead you have one paper that's folded into let's say like a bee-like structure and you try to stack those on top of each other they're not gonna lay as flat because of that kink right there's gonna be a gap and the density is gonna be lower meaning that for

unsaturated fats that have a kink they're not going to pack in as tightly and because they don't packing this tightly these types of fats are more likely to be liquid at room temperature and so these are fats usually more commonly associated with plants or fish etc these would be more likely to be unsaturated fats so what is the function of our fats fats are used as an energy storage my grandma fat stores twice as much energy energy as a gram of poly saccharide meaning that they actually store more sugar or I'm sorry they store more

energy compared to sugar and fats are stored in specially cells called adipocytes in adipose tissue and so the specialized tissue in the body is used to help store fat fats are also used to cushion vital organs such as the kidney fats are used to help insulate the body a layer of fat is found underneath the skin in something called the hypodermis and that helps to keep the body warm our next type of lipid is going to be our phospholipid and our phospholipid is going to be one glycerol which remember is a three carbon sugar to

fatty acid chains one phosphate group and one variable alcohol group and so what you can see is that if you look at that phosphate group that phosphate group is charged fatty acid chains are primarily hydrocarbons those are going to be nonpolar so you end up with this polar head meaning that that's one part of the molecule that has a charge and wants to interact with water and the nonpolar tails or the or the hydrophobic tails so you'll hear this referred to as the hydrophilic head it's water loving it has charges that want to interact with

water and the hydrophobic tails which are water fearing and don't want to interact with water so phospholipids are what we call amphipathic one end is gonna be polar right interacts with water that's the head and the other end is nonpolar and won't interact with water and that's gonna be our fatty acid tail and so because of this dual nature of a phospholipid phospholipids orient themselves in very characteristic ways they will orient themselves so that the hydrophilic head faces outside the cell where water is found and the hydrophilic head faces the cytoplasm which remember is also

primarily water so the hydrophilic heads will face where water is located both outside or inside the cell the hydrophobic tails right there water fearing they want to be shielded from the water and so the tails are gonna be the middle of the phospholipid bilayer meaning it's gonna be shielded from the water and so what you get is you get this phospholipid bilayer the heads face outside and inside and the tails are in the middle you can think of the heads as like the sandwich the bread of the sandwich and then the tails are like the

meat it's the stuff in the middle and so the reason that phospholipids orient themselves the way that they do is so that that hydrophilic head faces the water and the hydrophobic tails are in the middle shielded from the water our last type of lipid is going to be our steroid this is going to be a carbon skeleton with our four fused rings and varying functional groups an example of a steroid would be cholesterol and cholesterol serves a variety of purposes one it's found in the membrane of certain organisms like animals and it's used to help

maintain the correct fluidity of the membrane meaning to make it so that the membrane is not too solid or not too liquid but the correct viscosity the other purpose of cholesterol is that it actually serves as a precursor for all other steroids like testosterone and estrogen meaning that the body actually converts cholesterol into testosterone or estrogen and so when you think of cholesterol you don't want to always think of cholesterol as being bad cholesterol actually does have a very important use but it's too much cholesterol that has a negative outcome so question for you a

newly discovered lipid extracted from a rare Polynesian plant is solid at room temperature this is more likely to be read a saturated fat yellow an unsaturated fat green a phospholipid or blue none of the above so go ahead and take a minute pause your video and when you're ready go ahead and turn it back on and get the answer so go ahead so if you said red a saturated fat you would be correct because a saturated fat remember has no double bonds no double bonds means that it is gonna form linear molecules and those linear

molecules are gonna stack on top of one another much better and therefore are more likely to be solid at room temperature the next group of macromolecules that we're going to look at will be our proteins proteins serve a variety of functions in organisms the first thing that proteins can be used for is that they can serve a structural role meaning that they can be used to provide support for example could be used to give hair or horns their toughness or in the case of humans right keratin in our skin is used as a structural protein

it is a very very Hardy protein it acts as a good barrier to keep bacteria out and keep water in right bacteria certain bacteria also produce a structure called an endoscope and the endospore is also made of keratin and that endospore is to protect the bacteria during adverse conditions some proteins serve as storage proteins meaning that they are used to provide amino acids for growth seeds eggs for example are rich and storage proteins eggs have a protein called albumin it and that's used to supply the growing embryo with the energy that it needs in order

to grow and develop because you have to think about right if it's an egg animals will lay the egg and the mother is no longer providing that food source they have to have stored food in order for development to occur we also have contractile proteins which are used to help with movement for example muscles have a type of protein called actin in or I'm sorry they have a type of protein called myosin in them and myosin is a motor protein that interacts with actin and myosin walks along the actin like little feet and it's gonna

contract and it's gonna pull the muscle for muscle contraction proteins can also be used as transport proteins they're used to help move other molecules for example in red blood cells red blood cells have a protein called hemoglobin hemoglobin is a protein that will bind to oxygen and will transport oxygen throughout the body so when the red blood cells circulate to the lungs they'll pick up oxygen and then when the red blood cells moved through the circulatory system they'll drop off oxygen off at the various tissues and so hemoglobin would be a transport protein and then

lastly we have proteins that can act as enzymes enzymes are proteins that help speed up chemical reactions and so we've talked about a variety of enzymes in lab that help speed up different chemical reactions so proteins are the polymers and again the name of the monomers are called amino acids and amino acids are going to be our building blocks for our proteins remember that our polymer can either be called a protein or a polypeptide the difference being polypeptide is just the chain of em no acids proteins can be multiple polypeptide chains put together in terms

of the atoms that you're gonna find in proteins you're gonna find carbon hydrogen oxygen nitrogen and sometimes sulfur in certain amino acids now our amino acids are building blocks there are 20 different naturally occurring amino acids and what what you can see if you look at the structure of the amino acid we have this alpha carbon so this is the central carbon we have an amino group in a carboxyl group and again that carboxyl group adds as an acid acts as an acid meaning that it can donate hydrogen's to the solution which is why we

call this an amino acid now attached to this alpha carbon we also have this hydrogen and then the part that makes the amino acids different is going to be this R group so the R group is the variable part of the amino acid that's the part that's different in the twenty different amino acids and so each R group has a specific shape and chemical property for example glycine would have its our group would be a hydrogen alanine would be a methyl group it would be a ch3 if we look down here we have leucine so

notice the yellow represents the R group leucine is primarily hydrocarbons or we could have serine which has a hydroxyl group at the end and so these R groups come in three basic flavors or three basic categories we can have our groups that are nonpolar or hydrophobic like leucine because again leucine is primarily hydrocarbons carbon and hydrogen similar electronegativities therefore they share electrons equally again that means they're nonpolar they're also hydrophobic we could have our groups that are polar right or hydrophilic they will interact with water serine would be a hydrophilic amino acid because that hydroxyl

group that Oh H group is going to be polar and it's polar because oxygen and hydrogen have different electronegativities and so oxygen and hydrogen will not share equally oxygen has a greater electronegativity therefore will pull harder for those electrons oxygen will become partially negative hydrogen becomes partially positive now it's polar and it's hydrophilic other our groups can be charged or ionized meaning that if let's say you had a carboxyl group at the end of the R group that can become ionic when it donates its hydrogen to the solution and you're left with an O minus

on one of the oxygens and so these R groups have three basic types nonpolar polar or charged and depending on what are groups you have will dictate how the protein functions so to build the polymer of proteins remember that the polymer is also called a polypeptide or a protein and just like building any other macro molecule in order to build the macro molecule it's gonna be a dehydration reaction so to form that covalent bond between the monomers we have to remove a water molecule and so where does that water molecule come from well it comes

from one amino acids carboxyl group and an adjacent amino acids amino group and so we're gonna link that carboxyl group with the amino group and when we do this we're going to remove a water molecule and what's going to form is going to be a peptide bond and so a peptide bond is a covalent bond that links the amino groups there are amino acids together so instead of it being a carboxyl group it's now a carbonyl group but we have this peptide bond formed between the amino acids so what we end up with is we

end up with this polymer that has two distinct ends one group is referred to as the end terminus the end terminus meaning it's the free amino group notice this amino group is free but this one is not and this one is not because it's participating in this peptide bond so we have our free amino end here and on this end we have the C terminus otherwise known as the carboxyl end because that's the free carboxyl group this carboxyl group is in the peptide bond that carboxyl group is in the peptide bond and so we have

one free C terminus one free end terminus and so proteins have two distinct ends an end terminus and a C terminus and proteins can be several thousand amino acids long so these can be these very long polymers of amino acids linked together now in terms of amino acids amino acids exists in either of two what we call stereo isomers meaning that structurally they look the same except they're mirror images of one another and so you can imagine this like you're right in your left hand well very similar they if you were to lay them on

top of one another they don't line up perfectly because they're mirror images of one another amino acids are the same way they have what's called an Ella Meno acid or a D amino acid the L amino acid is the one that's found most commonly in nature it's the most more common of the two you'll learn later that the D amino acid for example in a capsule bacillus anthracis uses D glutamic acid and as result because the immune system doesn't recognize that D amino acid it doesn't know how to break it down and as a result

bacillus anthracis it's capsule is resistant to phagocytic digestion meaning the body can't break it down because it's this isomer of glutamic acid that the body doesn't recognize proteins only function if they're in their correct conformation which is their correct shape and linear chains of amino acids fold in very characteristic ways and it's dependent on the sequence of the amino acids so if we look and we look at on the left here we have our influenza virus and on the right is the protein called an antibody and antibodies have these Y shapes and the antibody has

this region that notice is complementary to these this influenza virus and so it's the shape of this antibody that allows it to recognize this influenza virus and if that shape has changed the antibody wouldn't work in the right way and so confirmation or folding and the shape of the protein plays a really big role in the purple we see lysozyme which is an enzyme found in tear and saliva it's used as a protection against bacteria because it breaks down peptidoglycan in bacterial cell walls and enzymes are typically more globular proteins because they have these grooves

what we call an active site where a particular substrate comes in and the enzyme does that chemical reaction on the right we have collagen and collagen is a structural protein and notice that collagen is made of three intertwining polypeptide chains and this particular conformation makes this be a good structural protein because it has structure and strength and so we're gonna look at the four levels of protein structure what we call primary secondary tertiary and quaternary quaternary exists in proteins that have more than one polypeptide chain and so we're going to talk about each type of

protein structure primary sequence is going to be simply the sequence of amino acids along the chain so talking about the sequence from the n-terminus because remember that proteins have two distinct ends an end terminus and a c terminus so the primary sequence would be what is the sequence of the amino acids going from the n terminus to the C terminus so we have in this example glycine threonine glycine glutamine acid serine lysine and cysteine prolene etc those amino acids in order would be the primary sequence of the protein and the correct sequence of amino acids

is determined by the cell's genetic information meaning it's the cell's DNA that's going to tell the cell what amino acid sequence to link together and so later on in the semester we'll talk about how DNA codes for protein but it's the cell's genetic information that will tell the cell what amino acids to put in what order secondary structure now is not simply the sequence of the amino acids but now it's the folding the beginning of the folding of the protein and so when we look at secondary structure there are two main types what's called an

alpha helixes and an alpha helixes is going to be a helical shape think of old telephone cords which have the coils coming down or they could have beta pleated sheets beta-pleated sheets are kind of an accordion like structure where it folds back and forth and so both of those structures though are dependent on hydrogen bonding between the backbone of the protein sequence meaning that it's not the are groups that are interacting it's those carbonyl groups with the amino groups that are in the peptide bonds it's those those parts of the amino acid that are interacting

so this is going to be an interaction among the backbone of the protein versus interaction among the R groups and so this is basically just coiling and pleating of the chain held together by hydrogen bonds within the backbone that's due that's different than tertiary structure or third level of structure which is now going to be this irregular folding and this is going to be determined by the R groups meaning it's the R groups that are now going to interact with one another it's not the backbone of the protein but instead it's the R groups and

there are several types of interactions that can happen we can get hydrophobic interactions between to our groups that are both hydrophobic we could get hydrogen bonding between two our groups we can get an ionic bond between a positively charged R group and a negatively charged our group we can even get a disulfide bridge which is gonna be a covalent bond between adjacent sulfur what are called sulfhydryl groups found on cysteine amino acids and so when we look at this if you think about these types of interactions so hydrogen bonds hydrophobic interactions covalent bonds ionic bonds

and you think about that certain bacteria live in let's say very hot environments for example you want to think about that one of the things that allows certain organisms to live and dirt different fireman's is that they have certain adaptations that allow them to survive and to thrive in those types of conditions and so if you think of bacteria that live in hot environments for example they have to have adaptations to their protein sequences or their protein structures that allows them to survive at high temperatures because remember in lab when we talked about heat fixing

right so when we make our slides and we do heat fixing step we said that the reason that heat fixing works is that because when you heat something up molecular motion increases and molecular motion increases until proteins start to denature so what that tells you is that bacteria that live in hot environments must have some types of adaptations that help protect against their proteins denaturing at higher temperatures and so if you think about the types of interactions found in tertiary structure one of the reasons certain bacteria can live in high temperatures is because their proteins

have more of one type of bond than another so if you think about these interactions which of the type of bonds would be the strongest and the answer would be the covalent bond and so that cysteine amino acid which forms the disulfide bridge for organisms that live in high temperatures their proteins are adapted to have more cysteine amino acids to form more disulfide bridges because that covalent bond is stronger which helps resist the proteins denature and lastly we have our quaternary structure this is not found in all proteins it's only found in proteins that are

made of more than one polypeptide chain so quaternary structure will be the interactions between two or more different or two or more polypeptide chains and these types of proteins we call oligomers they're made of multiple subunits and so you can have multiple polypeptides forming these large multi-unit proteins so for example in the case of hemoglobin hemoglobin is made of four polypeptide chains that would be its quaternary structure it has two alpha subunits and two beta subunits and so it's four polypeptide chains linked together therefore that would be the quaternary structure now remember that proteins only

function if they're in their correct conformation and their correct conformation is referred to as their native conformation this is the proper shape of the functioning protein however proteins can become denatured and that is when the protein becomes unraveled or unfolded and this causes this protein to lose its function because again it only functions if it's in it's correct conformation there are several things that can cause proteins to denature temperature is one that we've already talked about right because if we heat something up we increase molecular motion which can break the bonds between the R groups

for example and can cause proteins to unfold salt concentrations can also affect protein structure because you can think about those R groups you can have ionic interactions between those R groups if you add salt into the solution or into the cell that can affect the way that the protein interacts with the salt in the solution versus interacting within the protein s off and so if the protein begins to interact with the salt in the solution versus interacting with other R groups it can cause the protein to denature similarly for pH right pH is a measurement

of the hydrogen ion concentration in the solution if we affect the concentration of hydrogen's in the solution that can affect whether the protein interacts with itself or whether it interacts with the hydrogen's that are in the solution and if the protein interacts with the hydrogens in solution it'll cause the protein to unfold and it'll cause it to become denatured and so these are just some of the ways through which proteins can be denatured detergents also do the same thing basically anything that causes the protein to unfold will denature that protein and this is why a

high fever can be so bad for our body because proteins in the body can start to denature above a hundred and four degrees Fahrenheit and so if the body temperature gets above that it starts to denature proteins and proteins do a lot of different things in the body and therefore the cells don't function properly once the proteins become denatured so this slide is just summarizing what we talked about for protein structure so again primary sequence is simply the sequence of the amino acids along this chain it's what are those amino acids in order secondary structure

is going to be folding of the protein that's dependent on hydrogen bonding among the backbone and so again that can either be typically alpha helixes or beta pleated sheets tertiary structure is going to be when the protein begins to fold more and it folds because of the types of interactions found on the R groups meaning that you could have ionic bonds or hydrophobic interactions or covalent bonds etc and then lastly we have quaternary structure which exists in proteins with two or more polypeptide chains that are linked together now proteins don't always exist as simply amino

acids linked together sometimes proteins are conjugated to other organic molecules for example you could have glycoproteins what do you think glycoproteins have with their protein glyco refers to sugar so it sugars mixed with the proteins we could have nucleo proteins nucleic acids with the proteins we could have lipoproteins which are lipids with the proteins sometimes we have proteins that are linked with inorganic molecules like in the case of hemoglobin it bonds to iron and iron is an important part of that protein functioning properly so the last class of macromolecules that we're going to talk about

will be the nucleic acids so nucleic acids are made of the following atoms carbon hydrogen and oxygen those three elements you'll notice are found in all of our macro molecules even lipids lipids even have a little bit of oxygen we have nitrogen right and remember in lab we've learned that bacteria use nitrogen because they need it as a source to make their nucleic acids as well as their proteins and we just looked at proteins and nucleic acids also use phosphorus so the building blocks or the monomers of our nucleic acids are referred to as nucleotides

and nucleotides have three parts they have a Pinto spent meaning five it's a far five carbon sugar either deoxyribose or ribose sugar if whenever you see oh s--- OSE you know sugar right glucose fructose lactose etc O's tells you sugar so we have our pintos five carbon sugar we have a phosphate group and we have our nitrogenous base which is going to be our or our parameters and some examples of nucleic acids that you're going to see throughout the course DNA RNA ATP these are all examples of nucleic acids notice nucleic acids they are acidic

in nature and if it's a eukaryotic cell nucleic acids will be found in the nucleus remember prokaryotic cells do not have a nucleus so if we're looking at our pentose five carbon sugar this is going to be a five carbon sugar and it has this shape where it's a ring oxygen at the top and then the carbons are numbered one prime two prime three prime four prime and five prime and so if we look and compare DNA versus RNA DNA stands for deoxyribonucleic acids RNA stands for ribonucleic acids so a difference between DNA and RNA

is the type of sugar that's used in DNA versus RNA DNA if we look at carbon two DNA has a hydrogen RNA has this hydroxyl group and so for RNA the sugar and RNA is referred to as fri bose and DNA it's referred to as deoxyribose deoxy meaning it's missing an oxygen and that's why when we look at carbon two it lacks at the oxygen but the oxygen is found in ribose sugar so RNA uses ribose sugar it has the hydroxyl group at carbon two DNA uses deoxy ribose which is lacking the oxygen at carbon

two so when we look at the nitrogenous bases these are gonna be these nitrogen rich planar molecules and the nitrogenous bases can be broken down into two categories we have perimeters and purines and the way I remember this is perimeters longer name smaller rings meaning there only one ring big purines has a smaller name but bigger rings meaning they're two rings big and so there are three bases that are found in both DNA and RNA cytosine adenine and guanine those three bases are found in both DNA and RNA however a difference between DNA and RNA

DNA uses thymine RNA instead uses yourself so a difference between them again DNA uses diming RNA uses uracil but the other three bases they have in common now the way I remember which ones are perimeters and which ones are purines is perimeters has a Y in it cytosine and thymine which are both perimeters have a Y in them adenine a guanine no Y therefore they're not perimeters but instead they are purines when we are linking nucleotides together we get our phosphodiester linkage and again the way that this works is that we have this oxygen this

is a carbon one two three four five same thing here one two three four five and when we link our nucleotides together when we link our monomers together again same thing like always we're going to use a dehydration reaction we need to remove water in order to form that covalent bond between the nucleotides and the way that this works is we linked this five prime phosphate groups so here's our five prime phosphate with the three prime hydroxyl group and so this water molecule is going to be removed and we get this covalent linkage which is

referred to as a phosphodiester linkage and so it's the phosphodiester linkage that's going to link these nucleotides together and this is going to be a covalent bond now what ends up happening is is let me again renumber these 1 2 3 4 5 1 2 3 4 5 and so just like proteins which end up with two distinct ends member proteins have an end terminus and a c terminus nucleic acids also end up with two distinct ends we have a free 5 prime end which has the free phosphate group notice this phosphate group here is

participating in the phosphodiester linkage and we end up with a 3 prime end which has the free hydroxyl group this hydroxyl group is participating in the phosphodiester linkage so just like proteins have two distinct ends so do nucleic acids we have a 5 prime end and a 3 prime end now in terms of a difference between DNA and RNA DNA is double-stranded meaning two strands are linked together RNA is single-stranded and what that means is that for DNA it's like a ladder where the backbone is gonna be our sugar phosphate groups and the bases are

gonna be the rungs of the ladder and so what we're gonna get is these nitrogenous bases will form hydrogen bonds with one another and they will form what's called complementary base pairing and that is that a pairs with T and G pairs with C so we're gonna get a perimeter so thymine or cytosine paired with a purine which is adenine or guanine and so a pairs with T G remember that because G and C look the same so they go together so again if we're looking at DNA which is double-stranded DNA is going to exist

as a double stranded helix again the backbone is going to be alternating sugar phosphate groups the appendages are what sticks out towards the middle that's gonna be the nitrogenous base and again a would pair with T G would pair with C and when we get a double helix DNA runs anti-parallel and what that means is that this v prime end would loop around and the three prime end would be here and this one over here the chain on the right that's the three prime end so if we follow it down this is going to be

the five prime end over here so the two strands run in opposite directions it's not that they both run v prime and five prime going down it's that their mirror images one strand runs five prime to three prime the other strand runs three prime to five prime and so that's what we say DNA is anti parallel meaning the two strands run in opposite ends so what is the function of nucleic acids nucleic acids function to store and transmit hereditary information and so what that means is that if we look at DNA and let's say DNA

has a sequence of a gta2 G a and it's double-stranded so that's T G would pair C T is a TTT G C T what happens is DNA is responsible for storing genetic information now what happens then is that DNA is going to undergo something called transcription it's gonna be transcribed to a similar language it's gonna be transcribed from DNA to RNA now they're not identical right we've already talked about some differences between DNA and RNA DNA is double-stranded RNA is single-stranded DNA uses thymine RNA uses uracil etc the sugars are different DNA is deoxyribose

RNA uses ribose sugar but in transcription what's gonna happen is that enzyme called RNA polymerase is going to come along and it's gonna read the DNA and so let's say that this is my template strand meaning this is the strand of DNA that gets read the enzyme is going to read the a and on the mRNA it's going to put a and on the G it's gonna read the G it's gonna put a C T it's gonna put a a there's no T so remember you you you G C u so what we end up

happening what we end up having is that we're transcribing a similar language we're going nucleic acid to nucleic acid language mRNA stands for messenger RNA it's gonna be the messenger it's gonna take the information out of the nucleus if this is a eukaryotic cell mRNA is gonna exit out the nuclear pore and it's gonna come along to the ribosome all cells have ribosomes because ribosomes are responsible for the synthesis of the protein a process that's referred to as translation because now we're going from mRNA language to amino acid language and so the way that this

works now is that we're gonna get our amino acid and it's gonna read groups of three mRNA that we call codons so these codons will code for a particular amino acid for example uuu will code for phenylalanine and you CA will give some amino acid GCU will give another amino acid and so in translation we're translating we're going from nucleic acid information which is gonna be in the form of mRNA and we're translating to a new language which is gonna be amino acid language so we're going nucleic acids to amino acids and so notice that

in this way DNA is gonna store genetic information RNA is gonna be responsible for transmission of this hereditary information and in this way this is how the the cells genetic code its DNA will tell the cell what proteins to make now just to show you how important this sequence is sickle cell anemia is a genetic disease and in cycle cell anemia it's caused by a single base pair change meaning it's simply one nucleotide different it's one letter different in the beta globin gene and so we get a single base change in the D our DNA

which then means we get a single base change in the mRNA because again the mRNA comes from the DNA which also leads to a single amino acid chain change in the beta globin protein so this disease is caused by one single letter difference so how does this work well if we look at the normal beta globin sequence valine histidine leucine threonine prolene glutamic acid glutamic acid in the case of sickle-cell anemia we get one single nucleotide difference one single letter in the DNA sequence is different that one DNA sequence change leads to one amino acid

change so we go from glutamic acid at residue number six - now valine now you might wonder well so what it's one of you know acid different how much difference can that actually make and the answer is if you change the R group of the amino acid it can greatly affect the way that the protein folds because remember that protein structure is dependent on interactions among our groups for example and so in the case of valine valine is a hydrophobic amino acid glutamic acid is an ionic amino acid so you're totally changing the property this

one amino acid you're going from something that's ionic to now something that's hydrophobic and as a result it's going to change the way that the protein folds and so instead of forming this normal beta subunit it's gonna form this mutated subunit where the protein folds different and it has this exposed hydrophobic region now when we look at the structure of hemoglobin remember I said that it's made of four subunits two alpha subunits and two beta two alphas and two beta in the case of sickle-cell anemia the two beta subunits are mutated and so overall the

protein has a different structure and what ends up happening is is that these hemoglobin molecules because of this Mis folding the hemoglobin molecules tend to stick together and so you end up with these chains of hemoglobin all stuck together and you can imagine red blood cells being like a rubber band right if you have your rubber band and it's in its native conformation right it's circular in nature etc however if I take that rubber band and now I put a stick in it like a toothpick in it right meaning a chain of hemoglobin all stuck

together if I take a toothpick and put it in my rubber band my rubber band is gonna elongate and it's not gonna be this nice round circle anymore and the same idea happens with the red blood cells so for normal red blood cells they have this nice concave disc round shape however in the case of sickle-cell anemia because of that one amino acid different that beta globin gene or beta globin protein Mis folds hemoglobin molecules stick together we get these chains of hemoglobin and as a result it causes the red blood cells to take on

a sickle shape now all of this happens because of one single nucleotide difference and now you might wonder well okay so we have these sickle cells red blood cells why does that matter well it causes problems for several reasons one is these abnormally shaped red blood cells get stuck in the tiny capillaries which is where gas exchange typically happens in the body and so these capillaries are these little tiny blood vessels and these sickle-cell red blood cells get stuck in those capillaries and they cause reduced blood flow to the tissue that can lead to tissue

damage where this happens it can lead to a lack of oxygen in the tissue it can cause pain in the tissue where the blood clot is forming etc the other problem is that it greatly affects hemoglobins ability to carry oxygen so when hemoglobin molecules stick together like for sickle cell anemia hemoglobin is not very effective at picking up oxygen it's not able to pick up as much oxygen as say normal hemoglobin would be and so because of the fact that it's not as effective and picking up oxygen your cells need oxygen in order to make

ATP for energy and so when you get reduced when you get reduced oxygen to the tissues what's going to happen is the cells become fatigued right because they need that oxygen to make ATP if they're not making enough ATP they're not functioning optimally and that's where the anemia part comes in so when we say that you're anemic right you're not getting enough blood flow your your red blood cells are not efficient at carrying oxygen and as a result the patient experiences like extreme fatigue and tiredness because their cells are not making enough ATP and so

all of these all of these problems happen in a patient's body when they have one single letter different in their DNA sequence and so this DNA sequence is extremely important in terms of how the protein functions so what I want you to do is to just take a minute and compare and contrast DNA so for example what is the Pinto sugar and DNA what is the Pinto sugar and RNA DNA does it have a phosphate group yes or no RNA does it have a phosphate group yes or no in terms of nitrogenous base which bases

do DNA have which bases do RNA have how many strands does DNA have how many strands this RNA have what is the linkage between the nucleotides so what holds nucleotides together so what I want you to do is go ahead and pause the video work on this and then when you're ready go ahead and push play to see the answers okay so DNA pinto sugar is gonna be deoxyribose which remember means it's missing oxygen at carbon two RNA on the other hand uses ribose ribose has oxygen at carbon two so that's a difference between DNA

and RNA in terms of phosphate group does DNA have it yes does RNA yes because they're both made of nucleotides and nucleotides have a five carbon sugar a phosphate group and a nitrogenous base so that's the same between them they both have a phosphate group in terms of nitrogenous base they both have a C G a see G and a difference would be DNA has thymine and RNA has--is yourself number of strands DNA has to RNA has one linkage between nucleotides it's called a phospho diester linkage and that's the same for RNA the phosphodiester linkage

so question for you which of the following nitrogenous bases is not found in an RNA molecule so which one is not found in RNA is it red add name yellow guanine green thymine blue uracil so pause your video and when you're ready go ahead and push play to get the answer so if you said green thymine you are correct diamond is found in DNA only not in RNA adenine is found in both guanine is found in both and uracil is found in RNA only and so that concludes our video