okay guys so uh we talked about the basic cell structure the function of uh the each individual organel now what I'm going to do is I'm going to get a little more specific about the structure of DNA so let's take a little look at this video here and I'll do a little explaining for you all right so look any cell that is capable of dividing will have a nucleus and it will have DNA and DNA in every cell of your body contains all the necessary genetic instructions to make every protein in your body and remember that you have structural and functional proteins so they can make hormones which carry on all the chemical reactions inside your cells this is the important piece regardless of the cell that is skin cell liver cell pancreatic cell if that has a nucleus and it contains DNA it's going to contain all the genetic information to make all the proteins in the body now this is the important thing a liver cell only needs to make liver proteins it doesn't need to make pancreatic proteins so there has to be a way for chemicals from the blood to stimulate let's say a liver cell or a pancreatic cell to make their particular proteins and how a cell gets signaled from chemicals from the blood are based on the type of recept receptors that are placed on the cell membrane's surface so these cell receptors for different cells are going to be different this is what allows certain chemicals from the blood to affect some cells and not affect others and what are those cell receptors mostly made out of protein so let's talk a little bit about DNA and how it works first of all DNA is the biggest molecule you have in your body it's huge and it is made up of these organic compounds called nucleic acids not amino acids nucleic acids and there are basically four kinds of nucleic acids five but I'll four right now one is Adine Guan thiamine and cyto and when you chemically Bond those nucleic acids together you form a strand of DNA now the DNA you don't want it to get damaged you get a genetic mutation that's bad for you right you'll end up maybe with an eye in the back of your head or worse yet a genetic mutation that forces you to read the textbook and that's not even close to being good right so here's another little important thing and this says clinical implications nursing Adine and guanine are nucleic acids that are referred to as purines purines thyine cytosine are Pines now this is important when you talk about gout explain that later so if you chemically Bond these individual nucleic acids together and I'm making up this order you got me making it up right watch making this up right you're going to make this strand of nucleic acids this single strand of DNA is very unstable it can be damaged easily so the body always does stuff that makes sense so what happens in this big long strand of DNA if you take see I'm making this up a t g c t a right c c c this single strand of DNA is very unstable but to the body does stuff that make sense so to make sure that the DNA is much more stable less likely to get damaged there is a second chain of amino acids that's what makes up that latter looking effect of DNA and there is obligatory base pairing that goes with this chain and then the obligatory base pring this is very important a always matches with T so Adine always matches with thiamine and cytosine always matches with Guan so here's one side rail of the ladder and then when you chemically Bond those base pairs together in that obligatory fashion this little hydrogen bond forms the rung of the ladder and a always matches with t t always always matches with a G always matches with c c always matches with G so you match them up and when you do that what you will do is you will form this two chained complex this thing that looks like a ladder and when the charges on the two rungs of the ladder interact it will actually twist and that's what allows DNA to get into that double helix shape so again what do you need to know the four nucleic acids that make up DNA the obligatory based pairing that goes into making DNA a very stable molecule less likely to get damaged that's good for you and the obligatory based pairing always a with t c with G now what's really important to know is this only one rail of the DNA ladder or DNA staircase whatever codes for proteins all the proteins in the body codes for other stuff but in this class it codes for proteins the other rung is simply garbage it's singular purpose is to make sure that DNA is stable so let's look at this little video and as we go through the video I'll explain a few more things now this sounds like a good question too all right DNA comes in basically two Styles it comes on in packaged DNA or in the loose stringy form the package DNA are called chromosomes and we as human beings have 23 pairs of chromosomes you get 23 chromosomes from your ma 23 from your dad and when they come together you have 23 pairs of chromosomes 22 of them are referred to as somatic what does that mean they code they hold the genetic code to form all your physical IAL characteristics how tall you is how smart you is color your hair color your eyes stuff like that there the 23rd chromosome is the sex chromosome so if you remember from chrome chrome yeah I got it it's right there too anyways if you look at that little punet Square remember men are XY women are XX so if you do the little square right xxom xxom XY male XY male so you have about a 5050 chance of having a boy or a girl now look because women women both have the X chromosome and men have the XY chromosome because they have different chromosomes that make up their sex chromosomes um the man determines the sex of the child the woman determines when the man will have sex you should write that down now loose stringy forms of DNA uh before I end that um let me say this the only time that you see chromosomes inside a cell is when the cell is actively dividing so only in dividing cells will you see chromosomes now look I'm going try and simplify this watch if you got Junk L around your house if you're living there that's cool right but if you have to move what do you have to do you got to pack your stuff up you got to label the boxes and then you got to kind of organize it so you know what's going on so when the cell is on the move when it is dividing it's got to take that loose junk that's all over your living room and kitchen and it's got to package it up so packaged DNA are in the forms of chromosomes and the only time you see chromosomes inside a cell is when a cell is actively dividing so if a cell's not actively dividing and you look in the nucleus you're not going to see any chromosomes what you will see is loose unravel excuse me loose unravel DNA ready to make some proteins and loose unravel DNA ready to make some proteins is called chromatin and I'm simplifying this a little bit but that's okay so that's the difference between chromosomes and chromin now let's get into this a little bit remember DNA big molecule made up of those four B B is Adine guanine thyine and cytosine so you look here at look huge long DNA molecule we are looking now at a section of DNA this is important a section of DNA that codes for a particular protein that tells the cell how to put together the amino acids to make the protein not only the type of amino acid but the sequence of amino acids that section of DNA that um codes for a protein is called a gene and in the human DNA we have over 25,000 different genes that tell the cell how to put together proteins it does other stuff but for this class it tells you to how to put together specific proteins now let's look at this a minute you can see here you have this strand of DNA and these little building blocks these guys right here these are the nucleic acids so I'm making this up this is a T C and G right it's making up this part of the ladder what's the corresponding base pairs for the other side of the ladder a i matches with t t matches with a c i matches with G and G eyes matches with c and so it's going to form this rung of the ladder and remember only one side of the ladder tells the cell how to put together the amino acids to make the protein the other side is simply garbage it's there to keep it stable so in order for the cell to get the recipe to make a protein you have to break the bonds between those two chains and when a cell is going to make a protein it Cleaves those bonds between the A's the t's the C's and the G's and it reveals the two rails of DNA a so watch and a big thing that looks like a turd that's an enzyme will come in and it will break the connections between the A's the t's the C's and the G's so in this video it is showing that this rail rung of the ladder right this portion of the ladder this tells you how to put together the proteins the code for it and then this side is simply garbage to keep it stable now look DNA never leaves the nucleus ever so when a cell needs to make a protein it is going to activate the gene that section of DNA that codes for that particular protein now remember you have all the genetic information to make all the proteins inside every cell of the body but let's say you want to make insulin and this section of D shown this little video codes for the protein insulin would it make sense to unzip the entire strand of DNA exposing all these little bases where they can get damaged or would it make more sense just to unzip the section of DNA the gene that codes for the protein insulin well the second one makes more sense so that's exactly what happens so when a cell like a pancreatic cell needs to make insulin you got to get the recipe where do you get the recipe from you get the recipe from DNA so DNA is in a double helix to keep it stable so you have to break the bonds between the A's the t's the C's and the G's and reveal one of these chains of nucleic acids and this bare naked chain codes for all uh for the protein insulin again the other side is just for garbage so I'm going to leave that alone right there I'm going to end this little short video and then I'm going to talk to you about the process I'm G write this down of [Music] trans scrip oh that's too big the process of transcription now look if you copy somebody's test what are you doing you are transcribing it you're copying it right so what you have to do in order to make that protein is you have to copy that section of DNA that codes for the protein insulin in this case so DNA never leaves the nucleus so there is a different type of nucleic acids chemically bonded together that will copy that section of DNA that codes for the protein insulin so transcription is carried out by this stuff called m r n a the m stands for Messenger so it C copies the section of DNA and now it carries the message to the rough endoplasm reticulum and specifically the ribosome that will tell the cell okay buddy this is the code that is needed to string together the amino acids to make the protein insulin so next we'll talk about transcription and that involves copying the section of DNA a that codes for the specific protein all right okay hope that went okay right