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Main content
Current time:0:00Total duration:6:35
AP.BIO:
IST‑3 (EU)
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IST‑3.C.1 (EK)
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Video transcript

in previous videos on cell signaling we talked about the idea that if we have a cell right over there and let's say it has some type of receptor it doesn't actually have to be on the cellular membrane but I'll put it there for now and it is it can bind to some ligand that when the ligand binds to the receptor and it's usually particular the ligand is usually particularly the receptor and vice versa it can set off a whole cascade of events and in particular once it binds so let me actually draw the ligand bound to the receptor you can have a signal that tells the cell to do something it might tell it might activate some genes it might change the metabolism of the cell in some ways and this signal that goes from the receptor into the cell to make the cell behave in some way we call that signal transduction we call it transduction take the signal transduction and in a previous video it's kind of hand wavy about it and you might have been saying well how does a signal actually actually go into the cell how does it actually move through the cell and how does it actually make things happen and what I want to do in this video is I'm not going to go into all the details but I want to give you an appreciation for how transduction can actually occur and it hopefully it'll also give you appreciation for for how complex biological systems including you and me and even each of our individual cells actually are so this this pathway that we're seeing up here and you can see that there's a bunch of pathways that all kind of work together and overlap in terms of the enzymes and the proteins that are involved this as the diagram causes the classical map kinase pathway and if you're wondering what does map kinase stand for and oftentimes people will just say map k or MAPK it stands for mitogen m4 mitogen mitogen-activated protein kinase --is and you might be saying well what does mitogen what does mitogen mean well mitogen refers to things that cause cells to to my toes to to actually go into mitosis to start replicating themselves now what is so mitogen-activated so this this pathway is going to be active by a mitogen mitogen-activated protein kinase well a protein kinase a kinase and we've seen kinase is multiple times they're involved in many many many biological mechanisms these are general term for enzymes that help take a higher energy phosphate or especially a higher energy bond or a phosphate part of an ATP or a GTP and transfers them to different molecules and as they transform two different molecules it's able to leverage that energy to actually facilitate some type of a mechanism now as I said I'm not going to go into all of the details here this is actually quite complex but I want to make a little bit sense of it and you're actually going to we're actually gonna talk about a few proto a few proteins and a few enzymes that are actually fairly important to modern biological research so what you have right over here I'll start with this with this molecule right over here this is the ligand this is the ligand it's going to be released by some other part of the biological system from from some other cell and this EGF this stands for epidermal growth factor and the 1986 Nobel Prize in medicine was actually given for the discovery of EGF of epidermal growth factor now this is going to be the ligand this is essentially what's you know the when this attaches or when this binds to a receptor that's going to cause the signal to be transduced so you can have the transduction going into the cell and so you could imagine it's going to bind to this membrane receptor and so EGFR literally stands for epidermal growth factor receptor EGF receptor and it's part of this protein complex and once this binds it's able to help activate it's able to help activate Ras right over here and Ras and once again all of these names they have these interesting histories associated with them this stands for rat sarcoma rat sarcoma and sarcomas are cancers and in in in certain tissues in the body and it was first discovered associated with certain cat cancers that that rats that had certain sarcomas that they were able to see the the there were mutations in the genes that produced the RAS protein and because of those mutations the RAS protein that the enzymes associated with it were in there activated mode and because they were in the activated mode this mechanism was kind of overactive and and the the any of the stop signals weren't actually happening and so you can imagine a mechanism right over here that is about cell differentiation that if this mechanism proceeds it's eventually going to tell the DNA some portions of the DNA especially the portions of the DNA that are that are involved with DNA replication with cell division with mitosis those are going to go crazy and that's exactly what happens in cancer so this pathway is actually a very important pathway in cancer and you see you know right over here you actually see the map kinase it's often called or was originally called er k which is extracellular signal regulated kinase but this is an incredibly important pathway to do cancer researchers and they're they actively are looking for different types of drugs different types of molecules that can down regulate this type of pathway so the whole point of this video once again I'm not going into all of the details on the map kinase pathway but to give you an appreciation for how complex transduction is you have this cascade of the signal which is really this these phosphate groups originally transferred from a gtp going to the going to the brass and it keeps cascading down all the way until you actually have the DNA being told to or or you start activating you start activating mechanisms where the DNA is going to start a replicating and then the the cell itself is going to proliferate and differentiate and that's when it goes creating this hat needs to happen in practically every cells in our body but there's all sorts of there's all sorts of kind of factors that keep it from going crazy but if you have a mutation in something like the the Rast gene which codes for the wrasse protein then you could end up with an actual cancer cell so hopefully this gives you a little bit more appreciation for how transduction actually occurs
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