So here we're going to briefly revisit our map of the lesson on bio signaling pathways which is down below right here and of course we know that we've been exploring this map by following the left most branches first. And we've already covered G protein coupled receptors and G P C R. S. And all of these GPC are signaling pathways in our previous lesson videos. And recently we've transitioned to a new branch here for the receptor tyrosine kindnesses or the R. T. K. S. And so here in this video we're going to continue to talk about receptor tyrosine kindnesses as we introduce insulin and then the insulin receptor which is an example of a receptor tyrosine chinese. And so let's get started with insulin. Alright, so here we're going to introduce insulin, which is probably a word that you've heard before in your previous biology courses. And so you may already know that insulin Is really just a small protein or a small peptide for that matter. And more specifically, insulin is a small peptide with just 51 amino acid residues in it. And insulin functions as a hormone or a bio signaling molecule that can travel and affect other cells. Now, the reason that we're talking about insulin right now at this point in our lesson is because insulin is involved in classic R. T. K. Pathways or receptor tyrosine kinase pathways. And so as we move forward in our course, we're going to see very specific receptor tyrosine kinase pathways that utilize insulin now in our bodies, insulin signals the well fed state or the fuel abundant state. And so cells are capable of recognizing that uh we have just eaten a meal because we are well fed and that we have an abundance of fuel. Now when insulin is initially secreted, it's actually initially secreted as a as I imagine called pro insulin. Now recall from our previous lesson videos that's imagines are just the inactive precursors to active proteins or enzymes. And so initially it's going to be secreted as those imagine pro insulin by pancreatic beta cells in response to eating a meal. And again, when you eat that meal, you're going to be well fed and have an abundance of fuel. And so if we take a look at our image over here on the left hand side, notice that in the top here we're showing you the structure of pro insulin which again, which is again the is I imagine form of insulin. And so notice that pro insulin is a single polyp peptide chain here that has one amino end and one car box will end. But also notice that it forms these di sulfide bonds that were labeling right here. And so what you'll notice is that Zeus imagines are usually activated through prodi allyson or the cleavage of the protein. And so what you can see here is we are showing you the cleavage sites which are right here and there's another cleavage site over here uh indicated right here. And so essentially what's being cleaved off is this blue portion of the pro insulin poor teen protein. And so when this blue portion is cleaved off, that actually creates what we have on the bottom half of our image, which is the insulin protein. And so notice that the insulin protein because of the cleavage is actually existing as two polyp peptide chains, the red one and the green one here. But total there are 51 total amino acids as we indicated up above. And notice that these two polyp peptide chains are actually still di sulfide linked together. And there's also this di sulfide linkage within the same polyp peptide chain of above. Now, over here, on the right hand side of our image, which you'll notice is we're showing you a diagram of someone eating a cookie, some kind of meal here. And in response to again, eating a meal, we know that the pancreatic beta cells in our pancreas, which you can see our pancreas is right here. This yellow structure that we're zooming into here in the digestive system and the pancreatic beta cells here in our pancreas are going to secrete the pro insulin or the insulin uh into the bloodstream. And once insulin is in the bloodstream, it can travel to distant areas and affect cells in different areas. So insulin acts as a hormone when it's secreted into the bloodstream. And so the exact functions and biological roles that insulin has when it's secreted into the bloodstream, we'll get to talk about as we move forward in our course. But for now, this here concludes our introduction to insulin. And again, we'll be able to see insulin in very classic our tiki RTK pathways as we move forward in our course. So I'll see you guys in our next video.
2
Problem
Problem
Proinsulin:
A
Is synthesized in three parts and then assembled for storage.
B
Is more active than insulin.
C
Is synthesized as a single chain, folded and then cleaved into insulin.
D
Stimulates insulin secretion.
3
concept
Insulin
Video duration:
2m
Play a video:
Alright. So here in this video, we're going to introduce Insulin's three primary biological effects. And so, after eating a large meal like this guy down below right here, insulin can actually be secreted into our blood and signal many different effects throughout our bodies. And so we're not going to talk about all of the different possible effects that insulin can have. But moving forward in our clutch prep biochemistry course, we are going to talk about how insulin generates really three primary biological effects, and so notice down below. In our table, we have each of these three primary biological effects listed. And so as we move forward in our course, we'll talk about each of these three primary biological effects that insulin has inm or detail. Now, the first primary biological effect the insulin has is that it decreases blood glucose concentration, essentially decreasing the concentration of glucose in our blood after eating a large meal where the glucose concentration in our blood would be really, really high. And so really, this first effect here is probably the most well known effect that insulin has, and again we'll get to talk more about this effect moving forward in our course, and more specifically, we'll talk about the insulin RTK pathway that actually leads to this decrease blood glucose concentration. Now, the second primary biological effect that insulin has is that it can actually stimulate cell growth by regulating gene expression within the nucleus of a cell and again moving forward. In our course. We'll talk Maura about this particular primary biological effect, and we'll also talk about a different insulin rtk signaling pathway that leads to this, uh, stimulation of cell growth by regulating gene expression. Now, the third primary biological effect that insulin has is that it increases the synthesis of very specific lipids. And later in our course, when we talk about the bio synthesis and metabolism of lipids will revisit this particular primary biological effect then. But for now, this here concludes our introduction to Insulin's three primary biological effects. And again, as we move forward in our course, we'll talk more about each of these three. So I'll see you guys in our next video
4
Problem
Problem
Which of the following is NOT a biological effect of insulin after eating a large meal?
A
Increases the concentration of blood glucose.
B
Regulates gene expression to activate cell growth.
C
Stimulates the production of certain lipid molecules.
D
Decreases the concentration of blood glucose.
5
concept
Insulin
Video duration:
7m
Play a video:
in this video, we're going to talk more details about insulin's first primary biological effect, which is that insulin decreases blood glucose concentration. And so, after eating a high glucose meal, of course, the glucose concentration in our bloods is going to be pretty high, since again, we just ate a high glucose meal. And so insulin's primary job or primary function again after eating a high glucose meal is to help decrease that glucose concentration in the blood, which again is really high immediately after eating a high glucose meal. And so insulin can actually help to decrease glucose concentration in the blood in the following two ways that we have listed down below number one and two. And so, the very first way that insulin can help to decrease glucose concentration in the blood is, uh, that insulin will actually increase the expression of a glucose transporter called glute four and glue fours. Job is to import blood glucose into cells. And, of course, if you're importing blood glucose, then you're going to decrease the concentration of glucose in the blood. And so this is the first way again that insulin can help to decrease glucose concentration in the blood, and we'll be able to see this example down below in our image. Now, the second way that insulin can help to decrease blood glucose concentration is that insulin will actually indirectly affect CIDA Solich enzyme activity via bio signaling pathways. More specifically, rtk or receptor tyrosine chi nese bio signaling pathways. And it will affect the site of Solich enzyme activity in such a way that it will help to convert free glucose free glucose within the cell, uh, into glycogen. And so, of course, if we're converting free glucose into glycogen, then that's going to be decreasing the free glucose concentration inside of the cell and decreasing the free glucose concentration inside of the cell is really what's going to facilitate the diffusion of blood glucose into cells. And again, when blood glucose diffuses into cells, that is going to again decrease glucose concentration in the blood, which is again exactly what we say insolence Affect is all about decreasing blood glucose concentration. And so if we take a look at our image down below right here will be able to visualize what we've been talking about up above. And so notice over here on the left. What we have is a cell, and this is the cells plasma membrane. But within the cell, notice that we have these vesicles and these vesicles contain the glute four glucose transporter. But notice that when the glute four eyes in the vesicles like this, it's not actually being expressed. Its not able to do its job of bringing glucose into the cell, because again, the glucose transporters are in vesicles and they need to be in the membrane in order to allow glucose to come into the cell and then also notice. Over here on the left hand side, we have a relatively high glucose concentration inside of the cell. Now, of course, after eating a high glucose meal like this kid right here, who's eating this cookie here, packed with sugars, we know that the, uh, insulin is going to increase in our Bloods, and so there's going to be an increase in insulin after you eat a high glucose meal, and insulin is going to signal for these two events to take place. The first event is that it's going to signal for the increase in glute for expression and again, the second event is that it's going to, uh, signal for an increase in glycogen synthesis converting free glucose into glycogen. And so over here, on the right hand side, which will notice over here on the right hand side is that the plasma membrane over here is now, uh, expressing the glute for transporter. And so these vesicles that we're over here have fused with the plasma membrane so that they can express these again these glucose glute for transporters. And so this corresponds with the increase in glute for expression and then also noticed that over here on the right hand side that the glucose that glycogen synthesis has been increased. And so now we have a relatively low glucose concentration inside of the cell because glycogen synthesis is being increased. So you can see our glycogen structure over here. And so when we have a low glucose concentration inside of the cell on, of course, after eating the high glucose meal in our blood and notice up, here is our bloodstream. We know that there's gonna be a high glucose concentration after eating ah, high glucose meal like a cookie. And so when we have a low glucose concentration inside of the cell and a high glucose concentration in our bloodstream That's going to allow for glucose to defuse down its concentration Radiant. But it can only get through the membrane through the glute for transporter here. And so you can see here that we're showing the high glucose concentration in the blood on the glucose is able to diffuse through the glue for transporter into the cell where there's a relatively low glucose concentration. Since again, uh, glycogen synthesis is being increased. And so ultimately, these two events right here, you can see work together, toe help decrease the blood glucose concentration or the glucose concentration in the blood. And really, this is what we said the main effect of insulin waas that insulin is going to decrease blood glucose concentration again, as we indicated right here. And so this year really concludes our introduction to how insulin decreases blood glucose concentration. And later in our course, we're going to talk about the exact rtk signaling pathway that insulin is involved with, uh, to help elicit these two effects the increase in glucose transporter glue for expression and also the increase in glycogen synthesis converting free glucose to glycogen. And so I'll see you guys in our next video where we could get some practice with these concepts
6
Problem
Problem
What is the primary function of the peptide insulin?
A
To stimulate transport of glucose out of the cell and into the bloodstream.
B
To stimulate transport of proinsulin out of the pancreas and into the bloodstream.
C
To stimulate transport of glucose out of the bloodstream and into the cell.
D
The transport of epinephrine from the bloodstream to the cell receptor.
7
concept
Insulin
Video duration:
2m
Play a video:
in this video, we're going to talk a little bit about insulin. Second, primary biological effect, which is that insulin stimulates cell growth now, when the concentration of insulin is high. In some cases, insulin can also act as a growth factor. Now a growth factor is defined as a biological substance that stimulates cell growth, healing and or differentiation. Now what's really important to note here is that when insulin is acting as a growth hormone or growth factor, it's actually going to use a completely different bio signaling pathway than when insulin lowers blood glucose concentration. And so later, in our course, we're going to talk about two different bio signaling pathways that insulin is involved with. One of those bio signaling pathways will lead to decreased blood glucose concentration, and the other insulin pathway is going to lead to insulin stimulating cell growth, acting as a growth hormone. And so that's important to keep in mind as we move along in our course now down below. Here, in our example, notice that we're showing you how insulin can act as a growth factor to stimulate cell growth, and so notice over here on the left hand side, we have this cell and this Ellis accreting insulin, which we're showing like this, and in some cases insulin can act as a growth factor. And so it will bind to the insulin receptor, which we know is going to be a receptor tyrosine, kindness and rtk. And we'll talk more about that as we move along in our course. But it's going to, of course, induce signal transaction allowing for bio signaling, causing cell division essentially causing for a cell to multiply and divide. And so again, as we move forward in our course, will be able to talk about the exact, uh, insulin bio signaling pathway that allows it to stimulate cell growth. But for now, this here concludes our introduction to how insulin stimulates cell growth, and I'll see you guys in our next video.
8
Problem
Problem
The hormone insulin can function as a(n) ________________.
A
Secondary messenger.
B
Adapter protein.
C
Effector enzyme.
D
Growth factor.
9
concept
Insulin
Video duration:
1m
Play a video:
So recall from our previous lesson videos that insulin's third primary biological effect is that insulin increases lipid synthesis. And so insulin actually has a large effect on lipid synthesis. And in this video we're pretty much going to leave it at that. And that's because later in our course, in a completely different chapter, we're going to talk a lot more details about how insulin increases lipid synthesis. But for now, if we take a look at our image notice on the left hand side, we have this character who seems pretty healthy and uh pretty fit and he's eating this meal here. And of course, we know that eating a meal is going to lead to the increase in insulin. And of course here what we're saying is that insulin has a large effect on lipid synthesis and it will increase lipid synthesis. And so over here, what you can see is that lipid synthesis has been increased and our character seems much more lipid packed. Uh but again, this is really where we're going to leave it at. And later in our course, we'll get to talk more details about this idea right here. And so I'll see you all in our next video
10
Problem
Problem
What is the effect of insulin on lipid fatty acid synthesis?
A
It activates regulatory proteins that inhibit synthesis of fatty acids.
B
It increases the synthesis of fatty acids resulting in higher amounts of fat storage.
C
In causes fatty acids degradation by liposomes.
D
It decreases fat storage by converting fatty acids to energy.
E
None of the above.
11
Problem
Problem
Which of the following is NOT an effect of insulin?
A
It increases the rate of fatty-acid synthesis and storage.
B
It decreases the concentration of blood glucose.
C
It stimulates cell growth and division.
D
In stimulates the release of proinsulin from the pancreas.
