we are going to be talking about DNA chapter 6 which is nucleic acid and protein synthesis right off the bat I would like to say that this chapter is extremely important because not only is it important for your as syllabus it will come back to haunt you in A2 as well so knowledge of this chapter has to be carried all the way until you finish your biology for a levels if you are doing A2 as well by the way all right so without wasting any time let's just dive right into it okay so first thing first we want to talk a little bit about something called nucleic acids now what exactly are nucleic acids there are two types of nucleic acids which are just deoxyribonucleic acids and you go oh God what is that that is just DNA and you've heard of DNA before right me even if you don't know much about what DNA is you know its shape you know that kind of double those two strings kind of like spiraling around each other you've seen that you've seen a version of a DNA before and the second type of nucleic acid we're going to be looking at is something called ribonucleic acids and ribonucleic acids just basically mean RNA now students will of course ask do I have to remember the long name deoxyribonucleic acids and ribonucleic acids you don't you can just call them DNA and RNA now so we must talk a little bit about their similarities their differences um we must also look at what do they do why bother about it like you know what is their relationship with each other this is where this chapter is going to be like uh shedding some light into the problem so the basics let's talk a little bit about nucleic acids which are just DNA RNA DNA or RNA no matter which one we are talking about they are basically polymers and if you remember in chapter 2 polymers are just basically made up of repeating monomers linked together so if a question asks you is a DNA or RNA large yes they are they are considered large molecules because they are made up of many repeating monomers linked together by covalent bonds and as you can see I'm just throwing up structure of a DNA and also another one where I'm deploying on the structure of an RNA if you notice the DNA is made up of two twins are two strands and the RNA is only just made up of a single strand all right that's usually the case in in most situation um there are some exceptions though but the exceptions will only be talked about in A2 in chapter I think it's chapter 18 I think when we are covering viruses but under normal circumstances DNA usually have uh DNA usually has two strands and the other one is made up of one strand and those little circles especially the ones in the RNA that I'm just basically highlighting uh and also one in the DNA the one in there when you break them down you basically get something called monomers just like how every other polymer when you break them down like carbohydrates like starch or proteins when you break down starch you get glucose which is the monomer when you break down proteins you get amino acids which are the monomers same thing when you break down nucleic acids you also get the monomers and the monomers that make up DNA are known as DNA nucleotides and the monomers that make up RNA are referred to as something called RNA nucleotides so DNA nucleotides are just joined together to make DNA RNA nucleotides are joined together to make all right it's as simple as that so without wasting time let's basically look at the monomers which are the nucleotides so the basic structure of a nucleotide whether it is DNA nucleotide RNA nucleotides there are similarities and there are some differences let's look at the similarities first now no matter whether it's a DNA nucleotide or RNA nucleotide they will have two forms right uh they have a phosphate group okay the nucleotides will have a phosphate group they'll also have something called a pentose sugar and pentose sugar just basically means the sugar is made up of five carbons in chapter two we learned about hexost sugars and hexa sugars have six carbons and pentose sugars in this case are made about five carbons and the nucleotides will also have something called nitrogenous base the only difference over here is you notice that the nitrogen is based on the left is slightly bigger and the nitrogen is base on the light is slightly smaller we will dive into that a little bit deeper anyway okay now so I'm just zooming in into one of the nucleotides and I'm showing you how to number the carbon carbon number one number two number three number four and carbon number five is slightly on the top left side that's where five carbons form the pentose sugar that is also important to know you have to remember that the carbon uh in the nucleotide sorry the sugar in the nucleotide is made up of five carbon and I'm also just drawing it out just to show you how it fits into the pentose sugar so that's basically how it looks like right so now let's just dive into the nitrogenous base a little bit now the larger nitrogenous base are referred to as something called purines okay and the smaller nitrogen is based on the right is referred to as something called a pyrimidine see here's where uh some some of my teachers have said it's pyramid in some of my teachers have said it's pyrimidine I use pyrimidine so uh if your teacher uses prelimited it's okay biology is not an oral exam so you don't have to worry about it so purines generally have two ring structures as you can see the nitrogenous base it has two Wings one hexagon and one pentagon and uh the piling lighting is only made up of a single ring structure which is shaped like a hexagon now there are a few possible puvins that can exist and a few possible peelings are as follows adenine which is a guanin which is G and for pyrimidine the bases can be cytosine unicell or thyroid how I like to remember it is you have to cut pyromidants cut pyrimidines basically means um cut cytosine Universal and thymine that's how I like to remember it so these adenine guanine cytosine ulacyl and thymine are referred to as the bases all right so is this important to know yes it is important to know you will have to remember that adenines and guanines are referred to as purines which are larger nitrogenous bases and cytosines utensils and thymines are smaller nitrogenous bases are referred to as pyrimidate there are some implications to know this as well when we are talking about nucleic acids later so do these things matter yes they do okay now what we're going to be doing is we're going to be looking at the comparison between DNA nucleotides and RNA nucleotides here's where it becomes a bit easier there are only four types of DNA nucleotides and there are only four types of RNA nucleotides now we're gonna see the difference between DNA nucleotides and other new nucleotides C in DNA nucleotides in their carbon number two there is only hydrogen linked to carbon number two but for RNA nucleotides in their carbon number two there is an o h group so does that matter yes because in DNA nucleotides the pentose sugar is called a deoxyribose sugar but for other nucleotides the pentose sugar is referred to as something called a ribose sugar so some students will immediately say oh okay the reason why it's called deoxyribose sugar in DNA nucleotides is because there's no Oxygen in carbon number two that's a good observation basically so pentose sugar is basically a type all right and there are two types of pentose sugar which are known as deoxyribose sugar and ribose sugar and deoxyribose sugar is only found in DNA nucleotides and ribose sugar is only found in RNA nucleotides the next thing that we also have to see for DNA it has two types of for DNA nucleotides there are two types of purines as well adenine or guanine and they also have two types of plantains which are cytosine or thymine however in how many nucleotides the periods are still the same adenine and guanine same as DNA nucleotides however the polymerine is a bit different they can have cytosine which is C and they can also have unicell which is a base known as so that's the difference between DNA that's another difference between DNA nucleotides and aluminucleotides DNA nucleotides can have thymine as a base but they cannot have uterusal as a business and conversely RNA nucleotides can have unicellular base but not thin as always basically these are the difference between DNA nucleotides and RNA nucleotides so for example if I were to just basically draw out a nucleotide over here and I ask you is this a DNA nucleotide or RNA nucleotide you don't have enough information but at Carbon number two if I put an oh group you immediately know aha this has to be an RNA nuclear attack because the sugar is survival of sugar okay but if I were to put a hydrogen over there you know that this is a DNA nucleotide and because the sugar over here is a deoxy ribose sugar simple as that now if I don't tell you what type of sugar it is and if I were to basically label the base and I just say oh that base is timing is this a DNA nucleotid or any nucleotide this has to definitely be a DNA nucleotide it cannot be an RNA nucleotide because RNA nucleotides do not have thymine as a base simple as that and then for example if I basically put a base cytosis over here okay base cytosine we don't know if it's DNA nucleot or the RNA nucleotide we don't have enough information because DNA nucleotides can have cytosine and RNA nucleotides can have cytosine so we'll have to look at the sugar okay and if the sugar is having an having a hydrogen in carbon number two then it's definitely DNA it's a deoxyribose sugar and if it's a sugar with oh then it's an RNA nucleotide because it's ribose sugar that's basically the introduction to DNA nucleotides and RNA nucleotides