Practice - Biosignaling

as we move through the following questions, it's important that you try each one on your own before you listen to the answer. I'll pause briefly between each question, but you should actually pause the video and try to answer each question yourself or attempt all the questions and then watch the video to get the explanations. Now let's begin with Question one. And again, if you haven't tried to answer this question on your own, pause the video. Now the answer to Question one is e receptor ligand interactions. Now the scratch heard analysis is not something that you really need to understand the specifics of Basically all you need to know is it's sort of like what we talked about with enzyme kinetics. There are some differences here, some important ones, too, but you don't really need to worry about that. The main point is that the scratch it analysis is a way to find K D, which is sort of like K M for enzyme kinetics except K D has to do with binding affinities. Or, I should say receptor lag annd finding. So the scratching analysis provides data on receptor ligand interactions. Specifically, it's there, so that you can find that K d, which is again sort of like the equivalent of K M from enzyme kinetics. Now let's move on to question two. Uh, when G protein coupled receptors bind their ligand GDP is replaced with GTP in protein cheat. So, uh, essentially, um, when the ligand binds to the G protein coupled receptor, there's a GDP already bound in the Alfa sub unit of Protein G. Right. We have our Alfa sub unit, and in there we've got G D. P. When re behind Ligand, GDP gets switched with GTP and that makes our protein g active. And also remember that that g the protein G eyes a g t p ace. So it's going to very slowly break down. It's bound GTP back into GDP, so it's gonna inactivate itself. But also remember that that can be, uh, that can be sped up with those gap proteins where GTP ace activator proteins and just looking at the wrong answer traces. Here. These G protein coupled receptors are not ion channels. When the ligand binds to the receptor, we activate G. That's how they carry out their function. Other receptors, for example, are ion channels, but we're not gonna talk about those. Really. A dental cyclists is not immediately activated. G is going to go over and activate a dental ill cyclists, so it's not the immediate result of ligand binding, but it is a downstream result. It's what G does once it's activated. Uh, there's not going to be any sort of enzymatic reaction performed on the Lagan. Um, and three receptor itself doesn't synthesize. G G is already hanging out hanging out there. G is made not made by the receptor. Now let's move on to question three. So protein kindness A is al hysterically activated by cyclic A M. P. And you might remember that protein kindness, a protein kindness a has that regulatory sub unit, our and the regulatory sub unit is gonna be bound into the active site. So here's our active site and when cyclic amp when camp binds al hysterically to the regulatory sub unit is going to cause the regulatory sub unit toe, leave the catalytic sub unit and free it up. Thio do its job. So, in essence, protein kinda say, is Alice Terek Lee activated by cyclic a m. P uh and, um, the uh, the wrong answer Choices here are, you know, should be fairly obvious why they're wrong. Uh, it's not Covalin binding, right? This is Alice Derek Binding. So it has to be, uh, like, easily reversible. Covalin modification would not be easily reversible. Um, affected by cyclic GMP at the phosphor elation site. No, completely inhibited. That's the opposite. And hide realized by cyclic amp no, it's activated. All right, let's move on to question number four. The hormone activated possible light based C can convert Foster title in a hostel for five Miss Phosphate to Die sel glycerol and in a hospital triphosphate. Now the abbreviated names for these are we have P I p to and die. So glycerol That's dag D A. G and in a stall triphosphate, That's I p three. So you might be more familiar with those names Are those abbreviated names? But these are the actual names of the molecule. And you might recall that, uh, that fossil ape a C is going to snip the bond between the between the hostel phosphate and the glycerol, the phosphate title in hospital. And again, what you wind up with are these two molecules and recall that diacetyl, glycerol and calcium are going to be used to activate protein kind A C and A hostile triphosphate is going to open up those intracellular calcium channels. Right. Let's talk about Question five. The auto phosphor relation of receptor tyrosine kindnesses Remember receptor tyrosine, kindnesses, air special Because they could cost for, like, themselves. So that auto phosphor relation depends on everything you see here. So, diamond ization of the receptor, right? We have to have those two components come together, dime arise, and then they will be, um, activated. We're ready to go. We'll need ATP to provide phosphate for the foster correlation. Right? We're gonna use a teepee for that wagon binding. We need lijin to bind our receptor dime er in order for it to get the signal that it needs Thio do the auto phosphor relation and that ligand binding is going to lead to confirmation All changes in the receptor through the membrane, right? Ligand binding is going to change the confirmation of the receptor eso. First we have demonization, then lying in minding. Then confirmation will change in the receptor and then we're gonna use ATP to Foss for a late the receptor. So then, uh, you know, it can carry out its various functions. And remember, insulin was theme model we used for our receptor tyrosine kindness. Now, speaking of insulin, let's move on to questions. Six. After insulin binds to its receptor, both A and B happened glycogen synthesis becomes on and it should be noted that both A and B happen due to protein kindness be so glycogen synthesis becomes activated. And this was that. E don't want to say terribly confusing but, you know, slightly complex thing that's going on here. So protein kindness be is going to you inactivate g s k three and remember that G s K three normally in activates glycogen. Uh, plate I'm sorry like a gin synthesis about right phosphor Elise glycogen synthesis. So if protein kindness be in activates GSK three, then glycogen synthesis won't be inactivated anymore and it will turn on. So that's how protein kind of speedy leads to the activation of glycogen synthesis and protein. Kindness be also signals the cell to move glucose transporters, specifically glute four transporters from internal membrane vesicles right. They're gonna be stored in those ended zones and protein kind sp will signal for them to be moved from the those internal membranes to the plasma membrane so that mawr glucose could be transported into the cell. All right, let's finish up taking a look at question seven. So steroid hormones are carried on specific are carried on specific carrier proteins in the blood because the hormones cannot dissolve in the blood. Right? Steroid hormones. Those have that sterile backbone, and I'm not gonna draw it out. It's the four fused rings, right? Super hydrophobic. Those Those sterols are super hydrophobic. They can't move through the blood on their own. They can. Uh, it's not that they're too unstable. It's that there to hydrophobic uh, targeting cells. That's not what it's about, either. Uhh. They don't need any help passing through the cell membrane. In fact, they'll readily diffuse through the membrane because they're so, um, there's so hydrophobic or lipa Filic. Maybe I should say so. They don't need help passing through the membranes, and they don't need carrier proteins to help them bind their receptors in the nucleus. Um, they'll do that just fine once they get in. The problem is that they can't move through the blood on their own. They need carrier proteins because they're too hydrophobic to be in that Aquarius, uh, acquis environment. All right, let's flip the page.