hello cell bio students let's take a look at the lecture slides for nucleic acids the last a group of macro molecules that we have in chapter 3 for nucleic acids the monomer is the nucleotide and then the polymer that would be the nucleic acid I think the most commonly known one is DNA which stands for d oxy ribonucleic acid so the na part is the nucleic acid and as we know DNA uh makes up our genetic information which we bundle into chromosomes um during cell division and genetic information that's what we inherit from our parents right so this is the information that goes from parents to offspring what's common about the nucleic acid well there will be a sugar and then a phosphate and a nitrogenous base but we are going to see a couple of differences in terms of the sugar because in DNA it's a deoxy ribos sugar and then in RNA RNA is ribonucleic acid the sugar in RNA is a ribose sugar then the phosphate is going to be the same whether it's DNA or RNA but the nitrogenous base now we will have some similarities and some differences between the two nucleotides when we do go from having the monomer to the polymer the very special Cove valent bond that connects them is referred to as a phosphodiester bond so that's the very unique special bond that we see in this macro mod molecule a little bit more detail into the nucleotide so we have the sugar here and it's this location where we see a difference now there's all these numbers associated with the image and they are really important so we see just regular old numbers here the one the two the three these numbers are associated with the nitrogenous base so when you see just kind of standard numbers that's associated with the nitrogenous base and we have several different types that we'll take a look at in just a few minutes but when we get to the sugar component we see numbers and then we see a little Dash up there that means Prime when we get to the carbohydrate five carbon sugar here we have a one prime carbon we have a two prime carbon thre Prime carbon four Prime carbon and then there's the five Prime carbon these numbers are very important because nucleic acids have a direction to them the one prime carbon is always the one bonded to the nitrogenous base the two prime carbon this is the location where we see a difference between RNA and DNA RNA there is a hydroxy group here so you see the oxygen and hydrogen and that's just a regular ribos sugar that's why it's called ribonucleic acid because the sugar is just a regular ribos sugar now in DNA this is just a hydrogen at the two prime carbon and that's why it's called deoxy ribonucleic acid because it has one less ox oxygen than the typical ribos sugar the three prime carbon always has a hydroxy group and when monomers are adding together to form a polymer the addition always takes place at the thre Prime end of the molecule and that's what I mean by that directionality when you are adding monomers together in nucleo Tides they are always being added at What's called the three prime end so that would be here with this three prime hydroxy then we've got the four Prime carbon right here kind of the last one associated with the ring structure and then the five Prime carbon is the one that's attached to the phosphate group when we take a look at those additions we say it always goes from the five Prime to the three prime and now phosphates being negatively charged right here we see those negatively charged oxygens that makes DNA a negative molecule so we have what's referred to as a sugar phosphate Backbone in our DNA structure and our our RNA structure as well that we know will be negatively charged due to that phosphate group but we talked so much about DNA DNA is the largest molecule in our cell DNA for us of course is is inside the nucleus and it cannot leave the nucleus so that structure of the DNA is so critical to be able to turn on and off the genes and then RNA plays that really important role for getting the DNA message really the DNA instructions um from the nucleus to the rest of the cell here's a little bit more detail showing that sugar phosphate backbone and the directionality so notice we've got the five Prime end here and the three prime end at this location in between we're getting the phosphodiester bonds and they're highlighting all the the prime numbers of the sugar and then we've got that exposed hydroxy group at the three prime end that if we were to add any more they would be added at this part of the molecule now over here we're taking a look at the very specific nitrogenous bases that's what figure 315 is showing the very specific nitrogenous bases that we have in our nucleotides two of them you'll notice have two rings and those are referred to as the purines so the purines are bigger than the other ones and that's just how I remember them I think purines have two rings and when we take a look at the purines we have Adine and guanine those are the two nucleotides that make up the purines the one that ones that have the two rings the others are called peridin the peridin you can see just have a single ring structure and that consists of cytosine thyine and uracil now notice that Adine guanine and cytosine are in both DNA and RNA so those are three of the nitrogenous bases we find in both DNA and RNA when we get to thyine thyine is only in DNA and Urus is only in RNA I will not expect you to have these exact structures memorized but I do want you to know which of the nitrogenous bases are purines which are peridin which are in both DNA and RNA and which ones are unique to just DNA and just RNA I ALS o want you to know that the purines have the two ring structures and the perianes have the One Ring structures this is an image showing the phosphodiester bond in a little more detail than it was in our book so I got this from sciencedirect.com and I just wanted to emphasize here uh there's the phosphate for the phospho part and then the diester that's the bond here with the two oxygen so this is one Esther this is the other Esther and there's the phosphate right in between so we've got the three prime end of one nucleotide linking up with the five Prime end of the next one and then we've got the three prime end here with the five Prime end of the next one three prime to five Prime and we know that we're always adding at that thre Prime n so just wanted to show a little bit more detail of that phosphodiester Bond again the very specific and unique coent bond that we have in the nucleic acids and then over on this side the Highlight is showing um the Adine thyine guanine and cytosine these are the four nitrogenous bases that we have in DNA DNA is double stranded so that means there are you know two strands of the nucleic acids that then associate with one another and it is a double helix structure which means it's like a twisted ladder we're taking a look at this sugar phosphate backbone here and then in between there is hydrogen bonding with the nitrogenous bases and we're going to notice there's also very specific what we call base pairing you'll see that there's an Adine always pairing with a thyine you can see here as well an Adine and a thyine and we see a guanine always pairing with a cytosine Adine and thyine always have two hydrogen bonds and guanine and cytosine always have three hydrogen bonds what we also notice with the base pairing is that in each pair one is a purine and one is a perimidine one is a purine one is a perimidine and what that does is it maintains consistency in the diameter of the DNA double helix we know that hydrogen bonds are on their own not very strong they're just associations right and we need that in DNA because in order to activate DNA we must unwind it so with this double helix structure if it maintains that structure we can't um turn it on we can't turn on our genes and um transcribe them for protein synthesis so we have to be able to unwind and expose the individual DNA strands one will serve as a template for gene expression what we also notice in this image is the DNA double helix is anti- parallel that means we have a five Prime end here and we have a thre Prime end here that's the anti-parallel nature so notice it's not the same end that we have on this side so one is the five Prime end with the phosphate group at the end and the other strand is the three prime end with the hydroxy so you can see why it was so important to go over that each carbon in that five carbon sugar has a role and so it's really important to know what's going on at each of those carbons in the five carbon sugar here's a little more detail on those Hydro hen bonding Pairs and I definitely want you to know that there are three hydrogen bonds between the guanine and the cytosine and there are two hydrogen bonds between the thyine and the adenine and we know we're looking at DNA right because we see the thyine right we don't see thyine when we're looking at RNA so we know we're looking at DNA we're looking at the base pairing between the two backbones that takes place and this is just showing that when we have guanine and cytosine it actually holds DNA together a little bit tighter than a lot of Adine and thymine so these hydrogen bonds are not holding the DNA quite as tightly together than a guanine and cytosine linkage and some of our DNA we keep tightly wound up some of our DNA serves more of a structural role than like an activity role to turn on with jeans for example um so there are certain areas where we want to keep it more tightly together or maybe we want it a little looser we want it to be able to easily um open up and be able to do um gene expression and and activity DNA structure of course is the double helix which is this Twisted ladder structure however RNA is typically not doubl stranded RNA is typically single stranded we still have the sugar phosphate Backbone in RNA and then what else do we have we have Adine cytosine and guanine but then we see the uricel here right we don't see ayine thyine is not in RNA but we do see this uracil and when we get more into gene expression later in the class we will see how tightly connected these two are so if we're going to make a protein we need to unwind that Gene in the DNA one of the strands serves as a template for RNA to come in a special type called messenger RNA to come in make a copy from that DNA template and then the DNA of course would stay in the nucleus but that RNA that mes RNA would leave the nucleus and then go into the cytoplasm where the protein synthesis Machinery is located there are some other nucleotides I did want to mention you may have heard of them or some may be familiar and some may be may be new but one that you probably have heard of is ATP so adenosine Tri phosphate right and we associate ATP with energy in the cell right this is why we need oxygen inside of our cells because we use oxygen to make ATP and ATP is our main molecule to get work done in our cells this is what ATP looks like you can see there's the nitrogenous base there is the five carbon sugar and here is one two three three phosphat so that's what we call it triphosphate and what we do is we don't store ATP we have to make it when we need it but we do have a DP adenosine diphosphate which just has two phosphates on it um inside the cell and then we have just phosphate floating around so we have ad DP and P in the cell and we utilize oxygen to put the put that last phosphate on make ATP and then this last Bond that we have between the second and third phosphates is what we call a really high energy bond that Bond because we've got all these negative charges here right we know that like charges repel all these negative charges they don't want to be hanging around each other and that's why we call it a really high energy Bond because the bond really wants to break AP part and those electrons or that phosphate can then be donated to another molecule and it can be used to undergo a chemical reaction undergo something really important in the cell and provide that energy that is needed we will of course talk a lot about ATP in this class then we will also be talking about these other two that I have listed so we've got nicotinamide Adine dinucleotide or nad+ and flaven adenine dinucleotide or F A so NAD plus and F A what do these do these are really important electron carriers or Shuttlers that take electrons right because electrons are all about the bonds right so we're making bonds we're breaking bonds that's our metabolism and these are two molecules that will grab electrons from one source and donate them to another source a big role um is our cellular respiration of course but lots of other reactions right are making bonds and breaking bonds now nicotinamide and flaven Adine dinucleotide so both of these actually derive from B vitamins so we have the B vitamins niin and riboflavin those are really important nutrients right that we must get into our body so we can use them to help with our metabolism those B vitamins are part of our water soluble vitamins that are just really important to get in through our diet and they don't give us calories right like the proteins and carbohydrates and lipids do but there still vitamins we know are an important class of nutrients that we need to help us with our reactions in our body now we also have minerals in there as well so minerals also critical components that can be associated with proteins like when we talked about hemoglobin and we had the iron part in there associated with it um so it's just kind of neat to talk about that nutritional important component with all of these macro molecules right because you are what you eat so we got to get really good building blocks into our body so not just to build materials but then also to be able to do all of our important metabolic reactions here's the visual summary that they have at the end of the chapter I know we took a look at the visual outline at the beginning but I find these to be really helpful to just scan across and you know make sure do you understand everything that we went over um in the lecture material use this to kind of test yourself um to teach others share it with you know a classmate your family the tutors talk about it as much as possible write about it as much as possible um that's what gets it into your brain so the repetition is really really key for learning this material but I'm finding the the visual the extra little visual component they put in the chapters to be very helpful as study guides and of course another study guide includes the review slides I have at the end of the lecture material now I broke carbohydrates and lipids on this one because it was more of the material we were covering um at the beginning part but I do one and two are pretty general for all of them so dehydration and hydrolysis with all macro molecules that's a General one and then number two specific Cove valent Bond associated with each right so we've got the glycidic bond for carbohydrates we've got the eser bond for lipids we've got the peptide bond for proteins and then we've got the phospho diester bond for our nucleic acid so I do want you want to know all four of the specific Cove valent bonds then we get a little bit more detailed into the carbohydrates little bit more detailed into the fats here and there is another page right so then we've got proteins and nucleic acids this is what we went over in the the last video the components and then definitely need to be able to identify the name structure and chemical characteristic of those 20 common amino acids now we have a lecture quiz one coming up and lecture quiz one is going to cover chapters one 2 and three the emphasis for lecture quiz one is going to be chapter three so one and two are pretty much just real basic background and review material the emphasis for lecture quiz one will be chapter 3 now lecture quiz one I will not be testing you on number two too so I will not have images of the individual amino acids on lecture quiz one I will have it on lecture exam one so this is number two here you don't need to have this memorized in time for lecture quiz one but you do need to have number two ready to go for lecture exam one all right this will definitely be on lecture exam one and then a couple more things about proteins we went over in the last video and then six and seven we went over those in this video and we've now completed chapter three so get busy with studying this chapter again this will be the emphasis on our first lecture quiz and then in addition to these review slides remember to go into McGraw Hill connect and do those practice practice questions so those practice questions are not graded but they are there to help you study you can take those quizzes as many times as you want you can start them and answer a couple questions and then um go back to them so they're very easy as a study resource and I usually do take some questions directly from the practice questions and put them on either a lecture quiz or a lecture exam so we've got one set of practice questions that covers chapters one and two two and then a set of practice questions that covers chapter 3 and of course um don't hesitate to contact me if you have any questions