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BIOL 2301 Human Anatomy & Physiology I - BIOL2301 lecture06_0201
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00:04 All right, y'all, let's get party started because it is a
00:07 right? That's why you showed All right. So what we're gonna
00:12 today is we're gonna cover um basically different things. We're gonna finish up
00:17 uh how we send molecules back and across the membrane. I promise
00:21 it wasn't gonna be particularly interesting because . Uh but really the whole reason
00:26 this stuff is important because cells need talk to each other, right?
00:30 created these compartments that allow for specific to occur. And so now we
00:36 to be able to allow these specialized to communicate. And so we're gonna
00:41 at the different means of communication and it happens. And then from
00:45 what we're gonna do is we're gonna back out again and look a little
00:48 more at the anatomy. We're gonna at the surface of the cell,
00:51 it interacts with the uh how cells with each other and hold each other
00:55 . So we can create tissues. then finally, towards the end,
00:58 gonna deal with the question of mitosis we'll just kind of rip through all
01:02 . All right. But kind of big picture today is gonna be really
01:06 do cells talk to each other. so what we're looking at up here
01:08 this slide is kind of a continuation what we were looking at on
01:13 And we're basically saying, hey, order to get something across membrane,
01:16 gonna have some sort of mechanism that molecules to move back and forth.
01:22 so these molecules typically in your body hydrophilic, they like water, they
01:27 like being around fat. And so plasma membrane serves as a barrier.
01:31 we've got to put doors in the membrane and that's what these channels and
01:36 carriers are. The thing is, that these types of proteins are
01:41 very specific for what they allow to over. So like this door here
01:46 allow anything through it, right? long as it can open that
01:50 you can get pass through. It matter if you're a human male or
01:54 , it doesn't matter if you're a , it doesn't matter if you're a
01:56 or a rat, you can go that door. Mosquitoes can go through
02:00 door, right? So there's there's no specificity to what that door
02:05 in and out. As long as door is open, you can pass
02:09 the thing about proteins though, remember that they have a specific shape and
02:13 only recognize very specific things. And there is a high degree of specificity
02:19 these molecules. All right. So molecules like channels can be opened or
02:25 and when they're open, they will what they can recognize to pass
02:30 I'm gonna just kind of we're we're gonna look at a couple of
02:33 generic terms, but just as an , uh sodium is something you
02:37 you want to move uh out of . All right, because we basically
02:41 or sorry, you wanna move it cells. And so uh the mechanism
02:46 do so is primarily through channels, there are some carriers that do that
02:49 well. But just to give you idea, there's something on the order
02:52 200 different types of sodium channels in body. All right. So it's
02:59 just like, oh well, you , we'll just make something no,
03:02 is a high degree of specificity and sodium channel won't allow potassium to pass
03:06 even though potassium's a smaller molecule than is right. So the specificity has
03:11 do with the shape of the element the ion or the molecule and its
03:16 with the the parts of that particular . But this is what this is
03:20 of looking at. So they can open in this particular case, this
03:23 the open one. So it's allowing to flow through if it's closed.
03:26 , we say it has a a to it. And so what you
03:29 is you can open and close the . And generally speaking, when you're
03:32 about a gated channel in general gated , uh if you talk about one
03:38 open, it's just that the gate always open, it's stuck in the
03:40 confirmation. All right, with regard carriers, they have binding sites to
03:46 that again, recognize something specific. when they change their shape, that
03:51 site changes shape as well, which what this allows it to recognize the
03:55 is carrying. So the reason you're to bind something up and then let
03:58 go is because of that change, there's a limited number of, of
04:03 uh binding sites. And so, that should be routes. Um uh
04:09 , in essence, when you're moving , they're gonna be limited to how
04:13 they can move at any given just like the door, only two
04:16 can go through at a time. you're lucky, it's usually one person
04:19 a time. So there's a limit how things move. So the types
04:25 channels that we're gonna see, we to them as being gated because they
04:29 that, that door or gate to and they recognize or are activated by
04:36 types of modalities. That's just a word for saying different things to different
04:41 . All right. So like these just four examples, the most common
04:46 of modalities. So some channels are be are, are gonna be stimulated
04:50 open or close, dependent upon the around the molecule. We call that
04:55 gated. If they have a molecule binds to them, that causes the
05:00 to open or close, we call ligand gated. So whenever you see
05:03 word ligand, you can just think that binds something, that's all
05:06 that's all that it means. And , uh in either case, what's
05:11 happen is is that that either the electrical activity around it causes a
05:16 in the shape because of the electrical or the uh the side groups,
05:20 , the positively charging, negatively side are gonna reconfigure themselves to open or
05:25 when it comes to the leg in you're doing is you're buying something and
05:28 changes the shape and that causes the to open. All right.
05:32 typically, uh voltage gated uh and gating can be both in intercellular or
05:37 . So, the idea being is you'll find them either on the surface
05:40 you can actually find them inside the themselves doing things. And we'll see
05:44 of this probably later in the Mechanical uh sensitive is just fence word
05:49 saying mechanically gated. Um ever been by something pinched, stabbed, you
05:56 , something like that. We've already about the, the uh Indian burns
06:00 stuff like that, right? the reason you detect those is because
06:04 manipulating the cell and changing the shape the cell, right? So you
06:09 physically or mechanically changing the shell When you mechanically change the shape of
06:13 cell, you're mechanically changing the shape the uh channel. That's why it's
06:18 gated. And that's what it's detecting change in shape. So, usually
06:23 , pinching, ripping, that sort things is what these are going to
06:27 . And then we also have thermal channel, these are gonna be gated
06:31 very specific temperatures. Um, so you touch something that's really, really
06:37 , notice how it feels kind of . Have you ever noticed that?
06:40 , your body doesn't know the difference the types of temperatures. It just
06:44 that there's a change in the And so your brain registers change extreme
06:50 as the same sort of sensation. what you're doing is you're opening up
06:54 thermally gated channels. All right. they respond to changes in temperature.
07:00 promised this to you that we're gonna about this a little bit more the
07:04 and secondary active transport. And what we're doing is we're talking about
07:08 type of carrier when we're talking about active transport as a type of
07:14 All right. So think about a . Can you picture a pump?
07:18 ? A pump moves something in a direction and typically it's moving in a
07:23 it doesn't wanna go. And that's what active uh transport is. It's
07:28 something in a direction it doesn't naturally go. And so in this particular
07:33 , with primary active transport, we we're using energy directly. And in
07:37 case, what we're doing is we're energy that's being stored up in that
07:40 called A TP. And we're breaking last little phosphate bond and releasing the
07:46 and we're moving that energy to the of interest here. In this particular
07:51 , the pump. All right. this is the most common type of
07:55 in the body. It's called the potassium HP A pump. And what
07:58 doing is you're taking that energy so you can pump sodium uh into or
08:03 of the cell and you're moving potassium the cell. All right. And
08:07 what you can do if you can for a moment, I'm the plasma
08:11 , my hands represent the amount of inside and out of the cell.
08:14 I have a pump on the outside the cell, what's happening is is
08:17 move sodium out of the cell that's get good, bigger and bigger and
08:21 and bigger. And the sodium inside cell is getting less and less and
08:25 . Do you see what I've created ? A gradient? Right? And
08:29 gradient is a representation of potential right? Because where does the sodium
08:33 go? It wants to go back , right? It wants to create
08:39 . So this pump is doing that regard to sodium. And it's also
08:42 that with regard to potassium. So can imagine, I'm pumping potassium into
08:46 cell. It's getting bigger and bigger bigger and bigger. I'm creating a
08:49 energy. And so there's less potassium the outside, there's no more potassium
08:53 the inside. Where does potassium wanna ? It wants to go out.
08:57 right. So what we're doing with pump is we're using energy to create
09:02 energy. All right, it's kind acting for those of you who've taken
09:06 kind of acting like a capacitor. you don't know what a capacitor
09:09 Don't worry about it. All But the idea here is I'm using
09:13 to move molecules in a direction. don't necessarily wanna go and with regard
09:18 the sodium potassium uh A TPAS, telling you everything about it. It's
09:22 and potassium and the A TP is you what it's breaking right to get
09:28 energy and it's moving those ions in directions. All right. So
09:33 they're exchanging in this particular case. , what's interesting about it is that
09:38 move three sodiums for two potassiums, I don't think we have to talk
09:41 them for you. But what we've and this is what that second statement
09:44 , is we're creating an electrochemical We're putting molecules in, in,
09:50 of balance and they're now wanting to where they were previously, but they
09:57 to depend on another mechanism to allow to happen. The pump is just
10:01 there going, I'm moving you in direction. It's like bailing water out
10:04 a boat. I'm just gonna keep you out, pumping you out,
10:07 you out. All right. if this difference in ion concentration is
10:13 representation of potential energy, how can use that potential energy? All
10:18 Now, this is where it gets . All right, because your
10:23 your muscles, your cells in general gonna use this potential energy to do
10:28 of the things that it needs to . All right. Now, this
10:33 an example, a simple example of pump. All right. So what
10:36 have here is what is called a pump. What do you think it's
10:39 protons? Yeah, see easy right. So again, what am
10:44 using? I'm using a TP that is being uh uh added to this
10:50 , the proton pump. And what every A TP I use, I
10:53 one proton across the membrane. And I'm creating a gradient and now I
10:57 potential energy. This is actually used over the place. One of the
11:01 that's used that you've already learned about the lysosome. What am I
11:05 I'm using energy to pump protons into lysosome. So I can create an
11:09 environment so that the enzymes in that can do their work. That would
11:13 an example. But generally speaking, I'm using that potential energy. I
11:17 use something like this a secondary active system. And you remember what I
11:22 on Tuesday, I said here we're energy indirectly. And what that means
11:26 , is I'm using the potential So I burn the energy over here
11:30 this pump system. Now, I've stored up energy and I want to
11:34 advantage of that energy to do something . All right. So I'm gonna
11:38 the example that they have up which is a sodium glucose pump.
11:41 can see over here this is the potassium A TP A. So I'm
11:44 potassium in, I'm taking sodium Sodium wants to go back into the
11:48 but it's not allowed to. All , but there is something that also
11:53 to go in the cell but it because it doesn't have a mechanism to
11:56 . So glucose. Now let me you when you go and get
12:00 do you expend energy to get that ? Like if you stand at Taco
12:04 and you order your, your $5 , you're just sitting there having to
12:08 to other people's conversation. I isn't that energy use? Using right
12:12 of a pain in the butt. to be that there was a Taco
12:16 right over here in that building that rebuilding over there. So sad.
12:20 gone. It used to be Now it's like I saw an ad
12:23 Taco Bell last night, I was everything under $3. I said,
12:26 you kidding? When I was in it was a 50 cent menu.
12:31 , I digress. All right. do you want to spend energy to
12:37 energy? In other words, for that glucose that you get in your
12:40 , do you want to use that to move the energy around? Because
12:43 what glucose really is. The answer no, right? You wanna use
12:48 energy for important things, right? escaping tigers. We don't do that
12:55 . OK. When I was in now. Yeah. All right.
13:01 we don't wanna use energy directly, we do need to still move molecules
13:05 glucose into storage. And so what have is we have a system where
13:09 have a lot of sodium over here wants to go into the cell.
13:11 have glucose outside the cell that needs get in the cell, but I
13:14 want to expend the energy. So I'm gonna do is I'm gonna couple
13:17 movement of those two things together. so what I'm doing is I'm
13:21 hey, uh I'll let the sodium if the sodium brings in the glucose
13:27 it. That's what that molecule is . And so it allows it to
13:31 . All right. So sodium goes binds up to this thing and it's
13:35 , all right, I'll change my but glucose has to come along with
13:38 . And so when that happens, changes the shape of the molecule sodium
13:42 down its gradient, it's happy glucose up its gradient. So you see
13:46 we've done here is we've pumped something we didn't use energy directly. We
13:51 the potential energy of the sodium wanting move down its concentration gradient. And
13:56 do this all over the place, type of movement, whether it's in
14:01 same direction that the same porter if moves in opposite direction, that's an
14:05 porter is used to move many, things in the body. All
14:11 Now, I'm gonna show you two here. Do not write anything down
14:16 them. I'm not gonna test you them. I'm just showing you
14:19 OK. So this right here is example of many of the uh uh
14:25 many types of carriers and channels and and pumps that you see in the
14:30 . So here you can see there a sodium potassium pump, potassium
14:35 there's a sodium channel, here's another of sodium channel. Here's a,
14:38 co transporter, right? So that's active transport. Here's a channel,
14:43 pump, another uh uh in this , this is gonna be uh a
14:48 transporter. It's really an exchanger because going in opposite directions antiport system.
14:53 , why do I show you The reason I show you this is
14:57 in the previous couple of slides, given you examples of these types of
15:02 and these mechanisms are conserved for multiple . All right. So once you
15:10 what primary active transport is, it matter if it's sodium potassium pump or
15:15 calcium pump. This is circa or another example of a circa uh or
15:22 scared it's gonna go really far Here is a proton pump. Proton
15:27 are the same thing. They're just something differently. But the mechanism is
15:33 the same. A channel is a is a channel. They're just moving
15:38 things, right? A antiport system the same no matter if you're doing
15:45 or this. I'm sorry, that's cot transporters are the same. Here's
15:49 weird co transporter. How many of molecules is moving? Look carefully.
15:56 many is it moving? Four One sodium, one potassium, two
16:04 ? But is the mechanism gonna be different than uh say this one?
16:08 over here it's gonna move a potassium chlorine in that one. So it's
16:13 same sort of thing. One's going , one's going uphill and it's using
16:18 , that gradient to drive things So today is not the day to
16:23 them, but if you ever come them, it should be like,
16:27 , ok, I got it. like seeing a Ferrari and a
16:31 I don't know. Let's go with car again. Are they just
16:35 Just because one's fancier than the other a fancier name? And one has
16:37 little tiny, cute little horsey on . No, it's still a
16:41 It still drives you forward. One happens to go faster than the other
16:45 sexier than the other or whatever. right, the smart car is
16:48 isn't it? Yeah. Ok. I show you this so that when
16:55 look back at these things, you're , these are mechanisms that are being
17:01 to drive all sorts of types of in the cell. We good with
17:07 . OK. Getting scared. So you're talking about channels and you're talking
17:13 carriers and you're talking about pumps, talking about little tiny elements,
17:18 For the most part, sometimes you talk about a small molecule like
17:22 But generally speaking, there are bigger in the body that you need to
17:26 around that are too big for channels carriers and pumps. And instead what
17:31 have to do is you have to things that are gonna be encased in
17:36 vesicle. And so vesicular transport. remember we talked about vesicles already.
17:41 one of the things that we do the ves is we're going to bring
17:44 into the cell or we're gonna move out of the cell. And this
17:46 what vesicular transport is now because these big and they have to be shaped
17:51 they have to mane maneuver or manipulate around and bind them up uh through
17:56 snares that we talked about, they're gonna require some form of energy
18:00 All right. So energy is gonna used with vesicular transport. But the
18:04 here is I am creating a whether I'm bringing it in or pushing
18:09 out, creating a, a structure is um uh basically spherical in nature
18:14 it's gonna car contain within it, materials I'm either secreting or bringing in
18:19 it might include those things in which going to insert into the membrane.
18:25 we have some terminology here. All , endocytosis. When you see that
18:30 means to bring into the cell. right. And there are different types
18:35 endocytosis. When we're talking about adding to the membrane or secreting things.
18:40 would be the term that we would ? Do you think exocytosis moving out
18:46 the cell? All right, exo cyto cell and then the osis refers
18:51 movement because it's from kinesis. All . So, with regard to
18:57 so now what we're doing is we're this direction, we have some basic
19:02 . All right. So first is . So when we looked at the
19:07 of the lysosome and it came across bacteria, not the lysosome, the
19:11 that we're gonna bring in that That would be an example of
19:16 All right. So what we're doing ptosis and why it's distinguished from the
19:20 is that phagocytosis takes the membrane and extends the membrane outward and engulfs the
19:29 that it's, that it's uh containing trying to capture. All right.
19:33 you can imagine if this is my membrane, I'm reaching out and I'm
19:38 something and now there's something stuck inside vesicle here that I've captured. That's
19:43 . I've ate something and that's what means. Cell eating. All
19:48 So typically the neutrophils in your uh macrophages in your body, um
19:54 sort of, of large cell that responsible for destroying foreign invasion. They
19:59 of use this mechanism. Not this not a common mechanism. All
20:04 But it's large material. Another type was observed around the same time was
20:09 well, sometimes the membrane kind of , in vagin its. And so
20:13 that means is the, the membrane downward like this and then folds on
20:17 . So you can kind of see , it's kind of going down and
20:20 it folds on itself and then it a vesicle and the stuff that it's
20:24 here. So notice I'm not reaching . I'm I'm I'm going the opposite
20:28 . I'm capturing things that are not specific. So in phagocytosis, I
20:32 the bacterium, I go and get bacterium. If I see dead uh
20:36 from the cell, I go out grab it. That would be
20:39 Pinocytosis, I'm pinching a portion of extracellular fluid off. That's pinocytosis.
20:45 cell drinking. That's where pinocytosis And then when I was in
20:50 that was the limit to what we to learn. It was like,
20:52 , that was easy. And then discovered another mechanism. It's like,
20:55 , there is a certain degree of that we can observe. In other
20:59 , there are receptors on the surface the cell and they bind up things
21:04 when they bind up those things, congregate into a unique area that have
21:08 special networks underneath the plasma membrane. is called a clain coated pit.
21:15 what the clain does, it attracts bound up receptors. And when you
21:19 enough of them, then the membrane vagin its just like what we see
21:22 here. Again, the difference being you have something bound up and what
21:26 does is it engulfs all those receptors that specific molecule bound to it and
21:32 it removes that molecule and then returns receptors back to the surface through a
21:37 of exocytosis. So what I've done this case is very specific. I
21:43 seeking something specifically and I have a to catch those things. So that
21:50 be receptor mediated endocytosis. So notice first two, well, really
21:59 not specific receptor mediated endocytosis specific. , there are other types that I
22:04 even know if I have them up . I don't on purpose uh that
22:08 kind of come to light as the gets better different mechanisms. But the
22:13 here is to demonstrate if there's something too big to use a channel,
22:17 are ways to get them inside the . Granted they're still in a
22:21 but I can then attack that vesicle lysosomes and other means to get the
22:26 out of it. All right. , these are all our mechanisms.
22:30 , channels carriers, vesicles, pumps. These are all mechanisms to
22:36 molecules around and what's gonna happen is I'm gonna use these different
22:41 sorts of methodologies to talk to other . All right. Now, let's
22:47 back up a couple of years. right. Probably before the COVID
22:52 And do you remember being in class being bored out of your skull and
22:55 writing that little note to a I guess you guys probably didn't do
22:58 . You always had phones. So gonna be a completely different metaphor,
23:02 we didn't have phones. And so I had somebody I wanted to talk
23:05 in the front of the class, would I do is I had to
23:07 a note and I would pass it somebody who would pass it to
23:10 to pass it and eventually it would to that person. They'd read the
23:13 and then they'd giggle up there and the teacher would say, what are
23:15 giggling about? And you'd sit there go, I'm not giggling. I
23:18 a cough. That's what I you know. So, how do
23:24 from different parts of the body, to each other. They pass
23:28 All right. And they're gonna do in different ways. Have you ever
23:32 a note to yourself? Yeah. . So, you know how to
23:36 a note to yourself? Have you written a note to somebody that you're
23:39 next to? I'm, I'm gonna tell you how bad of a student
23:42 was, there was a girl and , who sat next to each
23:46 we shared a note, uh, textbook. The textbook was a teacher's
23:50 that she got from her father. we didn't study at all. This
23:53 geometry way back when. So it really bad. So we would just
23:57 there, we would scribble in each in that book. We just go
24:00 and one day the teacher uh, to bring the textbook in class.
24:03 sat in the front row and he , can I borrow your textbook and
24:06 it? And he starts looking he's like, this is a teacher's
24:09 and it's like, oh, I, I forgot mine. I
24:11 to borrow my dad's like that was bad. But the idea here is
24:17 sat next to each other and we to each other by scribbling in the
24:22 . Right. And then of we know that you can write ha
24:25 a note and pass it back or it forward and stuff. Cells do
24:28 exact same thing. They talk to , they talk to nearby neighbors and
24:32 talk to people across the body, ? And that's what we're gonna be
24:36 at. All right. So, signaling is simply the way cells talk
24:41 each other. All right, they in different ways based on proximity,
24:47 on how fast the message needs to and who that intended target's gonna
24:51 All right. So they're gonna use methods. There are two basic types
24:55 signaling and that's really what this whole MP class is about. The first
24:59 is how do we talk? How we make these cells do things?
25:02 most common type is through chemical All right. So here a chemical
25:07 gonna be released from the cell and gonna travel in the extracellular fluid to
25:11 cell that it's supposed to be communicating . So this is like that's like
25:15 gold standard, but it's not particularly . All right. So the other
25:20 that's used is, is an internal system that uses electrical signaling. All
25:26 . Now, there is some a to cell electrical signaling. Like think
25:30 your heart. Your heart uses an signal to tell the cell next to
25:35 what to do. But for the part, even the nervous system,
25:39 , you'll hear it referred to over over as being an electrical signal.
25:41 the nervous system primarily uses chemical. what they do is if I want
25:46 send a signal quickly from one part my body to the other. I'm
25:49 use an electrical signal across the cell go that distance just as an
25:54 All right, if I wanna wiggle big toe, the nerve fiber that
25:58 that signal begins in my spinal cord all the way down my leg and
26:05 all the way down to my big . So it's roughly what, 2.5
26:08 long, it's a pretty big right? And your body has nerves
26:14 long all over the place. And what I'm doing is I'm taking an
26:18 signal from one side of that cell moving it to the other side of
26:20 cell so that it will release a message. All right. So the
26:25 majority of stuff is chemical, but speed things up, what am I
26:29 do? Electrical? All right. it's gonna be within the cell
26:34 with very few exceptions to that So let's go through the methodologies first
26:42 to myself. Like I said, written a note to yourself. You
26:46 to go to the grocery store. do you do? You make yourself
26:48 list? That's a note to remind what to do. We call this
26:51 signaling. All right. So what we're gonna do is we're gonna
26:55 , for example, you can see my vesicle, I release that chemical
26:59 . It goes out into the extracellular . But on the surface of the
27:02 , I have a bunch of receptors recognize that particular message. So I'm
27:06 the myself what to do. if you're probably sitting there going,
27:11 would I ever waste the time? can't I just spend the time talking
27:15 ? Well, part of that is maybe what you're doing is you're
27:19 another pathway. Maybe I'm doing ABC and step E gets released and what
27:26 does is it tells step A to to stop doing what it's doing.
27:30 might be a reason. All Maybe you're not just talking to
27:33 maybe you're actually talking to other cells well and you just happen to be
27:37 communicating with yourself in terms of that . All right. So whenever you're
27:43 with any sort of cell signaling starting for every chemical that you're releasing,
27:47 need to have the appropriate receptor. you don't have the appropriate receptor,
27:50 not gonna happen. So, autor , I'm releasing the chemical, it's
27:55 to the right receptor for that chemical regulate something inside the cell that released
28:01 . All right. That's number Pretty simple. Yeah, I figured
28:05 one's the easy one. All then we get into a group of
28:10 called Perrine signaling. All right. , Perrone signaling, I'm gonna release
28:15 chemical message. And what I'm doing I'm uh releasing to the surrounding
28:21 All right. Now, we've got be kind of clear here. These
28:24 cells that are nearby, they're not to, they're not touching the cell
28:29 being released. All right, because a different type of signaling. But
28:32 we're doing is we're saying, nearby neighbors. Uh Here's a message
28:36 want you to deal with respond as appropriate. Now, some of
28:40 cells will have the appropriate receptor. of them won't only the ones that
28:44 the appropriate receptor are going to So this is Perrine signaling. In
28:50 little example, down here, we a neuron. So this is where
28:54 electrical signal would occur. But down , what we have at the very
28:58 of the neuron is it's releasing a message. So this is a form
29:02 Perrine signaling. All right. we might actually even say that it's
29:07 different type of Perrin signaling that we're get to on the next slide.
29:11 right. So Perrine signaling releasing out the extracellular fluid, nearby neighbors,
29:19 neighbors that respond are gonna have the receptor. So far. So
29:25 the type of weird Perrine signaling that distinguishing from the nearby neighbors is called
29:32 signaling. In juxta, juxta refers next to, all right. So
29:39 some sort of interaction that's going on the two cells that are next to
29:45 another. All right. So in top example, up here, we
29:49 an example of direct contact. And direct contact is one cell has a
29:57 . Remember what is a ligand, that binds another res uh molecule.
30:04 I'll have a lund on one and the other, I'll have the
30:07 And when these two cells come the ligand and the receptor recognize each
30:11 and that's when the communication occurs. right, your immune system uses this
30:16 the time. But this is also cells actually attached to one another.
30:21 is called a process called cell to recognition. It's like when you go
30:25 you meet somebody and you shake their and you look them in the eye
30:28 say, hey, it's good to you, my friend and you continue
30:31 the conversation. That's the recognition. a communication that's going on when you
30:36 touch and shake hands. All The other type is what you see
30:43 you have gap junctions, we're gonna about what a gap junction is a
30:46 bit later. But in general, you can think about is basically two
30:49 are attached to each other and they a pore between them so that ions
30:53 move back and forth in between. right. So here again is one
30:58 can produce a chemical that then goes binds to an internal receptor inside the
31:05 cell. So one cell is directly to the other cell through these
31:10 This is how your heart works, ? And in the case, your
31:14 , it's ions moving. So you'll one cell connected to another cell connected
31:17 another cell connected to another cell, long chain. And this one has
31:22 flow of ions that gets shifted to next cell, which creates that
31:26 causes that one to fire, which the next one to fire, which
31:29 the next one to fire all the down the chain. And this is
31:32 your heart beats rhythmically is because of gap junctions and this juxtaposition signaling.
31:41 right. So juxtaposition or juxta signaling a type of Perrin signaling. But
31:47 , what we're doing is the cells directly uh connected to one another,
31:52 next to neighbors, they're not nearby . All right. Does that make
31:59 ? That can be confusing. We're back there. I got a,
32:05 got a blink on that side. we good back here? All
32:09 back over in this corner. All right. You think when I
32:14 ? You're like, no, I get it because it creates a gap
32:20 the cells. All right. And I say a gap, think of
32:22 like um you have a, you two rooms right next to each other
32:25 you knock a hole through the two the wall. So you create a
32:29 in between them. Yeah, that's good, that's a good question.
32:34 Wayne, you told me that people science name things simply I don't understand
32:37 when I think of a gap. think of a space. Yes,
32:40 just where the space is located. right now. You think when I
32:45 and ask if you guys understand do you think that this might be
32:48 that a lot of people struggle Yeah. Uh huh. Uh
32:58 we just, so what we do we say the cells themselves are in
33:03 with one another but direct contact. I'm dealing with here is a receptor
33:07 uh interaction with a gap junction. is no receptor ligand interaction except internally
33:14 the cell. Is it closer? , it's no closer than All
33:18 bad example. I'm gonna give you bad example already shaking your hand.
33:22 that direct contact? Yeah. How kissing? Yeah, but I'm also
33:30 something, right? What do we it? Changing spit, right.
33:34 . So same, same thing, ? It's a, it's not any
33:39 . It's just a different type of interaction. Yeah. Oh That's a
33:48 question. All right, we're gonna the question to the class. Do
33:51 think that a gap junction is faster slower than direct contact faster?
33:58 Why bingo? Basically, it is exchanging from one cell to the
34:05 It's it's very, very quickly. that is a really good question.
34:09 like that. That's, that's thank . Continue. OK. Now you're
34:17 a qualitative question. Is it faster , so with regard to all the
34:22 of cell signaling that we're looking at for electrical. I would probably say
34:25 yes, because it kind of falls the category very often into the category
34:29 electrical. All right. So the is that the fastest, maybe?
34:36 right, and notice my reluctance of committing to that answer.
34:40 So another hand here and then over . Yeah. Yeah. Ok.
34:47 . Oo itself, they can. once you move beyond yourself, so
34:57 specifically refers to talking to myself, ? So auto cell, but once
35:02 molecule moves and starts talking to other , and you can say,
35:05 that's Perrine signaling there, right? it's just a distinction in terms of
35:09 that is going. So if I'm my own signal that I'm doing autor
35:14 , but that signal, that's that cha or that chemical I've released
35:19 also have a Perrin component to right? Because I could be talking
35:22 nearby cells. So these are just of ways to define the type of
35:27 . So if I'm releasing a I just ask the question.
35:29 what type of chemical uh communication are doing here? Well, there is
35:32 type of Perrin signaling. OK. , that just means nearby says,
35:35 , this is a, well, primarily talking to myself. Oh,
35:37 long distance signaling which we're gonna see . Oh That means I'm sending a
35:41 of long distance away. You can multiple, right? But we're talking
35:46 in a very generic way and it's a way to kind of communicate or
35:50 if I'm talking to you about something like, if I say Perrone signal
35:53 in your brain, you think? , ok. Well, that's what
35:56 means. That's all that's that we're here. It's creating a common language
36:02 far. We're good. OK. slide is a long distance signaling.
36:07 . Yeah, he said he was get here. The other term you'll
36:10 when you hear long distance signaling is endocrine. All right. You
36:14 endocrine has gotten a little bit more loosey goosey with what its terminology
36:19 And that's OK. That's not a . But generally speaking, what we're
36:22 is we are releasing a chemical methods needs to travel a very long distance
36:28 from its source and most chemicals don't circulate through the body. You
36:33 that's, that's kind of a dangerous to happen is to release the chemical
36:37 there and say, well, go your way. So these molecules are
36:41 protected in some way. And what gonna do is they're going to enter
36:44 the bloodstream and they're gonna travel throughout body until they come across an area
36:49 those particular uh cells with the right are gonna be located. So this
36:56 when we talk about hormone signaling, is kind of what we're talking about
36:59 . And here's, here's one that's real simple right in your brain.
37:03 gonna talk about all these things a bit later. You have a hypothalamus
37:07 the hypothalamus talks to the pituitary, they're only about this far apart.
37:11 that would be an example of long signaling because they are not right next
37:15 each other. There's a distance because we're talking about molecule level distances,
37:20 ? And then so the hypothalamus releases that acts on the pituitary gland,
37:24 pituitary gland produces hormones and they go over your body. One of the
37:28 they'll go is to your adrenal right? And so the reason you're
37:32 is because your brain gets a signal says, hey, the water concentration
37:36 the body has dropped a little Uh We need to create a signal
37:39 from the pituitary gland, we're gonna a signal down to the adrenals to
37:44 , start releasing this hormone and that then goes back out through all the
37:49 . And so here what we're dealing we're dealing with a hormone with a
37:52 and a hormone to create a chain events to make you go get a
37:56 of water. All right. But , did I talk directly to the
38:01 gland with the nerve? No, sent out a chemical message. And
38:05 it might take a little bit of to get to where it needs to
38:09 . It's in circulation, it goes the blood and sometimes it goes out
38:13 it says, all right, I'm and it's like, oh,
38:15 there's no cells with the receptors and it goes back into the blood and
38:18 it keeps traveling around and says I'm . And if it finds the location
38:21 the right receptors, then the message delivered. So why would I do
38:26 this way? It seems really, inefficient because many hormones act in multiple
38:32 . All right, just use the of estrogen. For example, where
38:35 estrogen act? Let's just name some , ovaries. Is that an easy
38:41 ? Ok. Good. Uh breast . That's a good one,
38:45 Uh How about skin? Anyone here acne when they hit puberty?
38:50 OK. So we got that. what about hair? Do I see
38:54 here with male pattern balding? You're little bit young but you never know
38:58 , my best friend in high the one that was a blueberry that
39:00 into the he uh he started losing hair in high school. Why estrogen
39:07 , right? So here's a hormone doesn't act on one tissue or two
39:14 , it acts on multiple tissues. so by sending that signal outward,
39:20 able to hit multiple places at the time. All right. So let's
39:27 . Um uh in terms of which systems do this, your the nervous
39:32 plays an important role in long distance . The endocrine system by its name
39:37 tell you long distance signaling. what are we doing with these
39:41 What's going on? How, you , fine, I'm releasing a signal
39:46 goes someplace. What is it Well, what we're dealing with here
39:50 two different mechanisms of how a chemical on a cell. All right.
39:56 are broad, again, broad The first type of signaling is called
40:02 . And you can see the first of that word is from the same
40:05 as metabolism, right? So I'm a chemical reaction. And so what
40:11 see here is I have a signaling that cannot get into the cell.
40:17 right, it's hydrophilic. And so needs a receptor on the surface of
40:22 cell for it to recognize. And that signaling molecule finds that receptor on
40:26 surface of the cell that changes the of the receptor, which then activates
40:30 series of molecules. In other it's basically like a Rub Golder Goldberg
40:35 . This molecule turns on another molecule turns on another molecule which turns on
40:39 another molecule. What we're doing is taking an outside signal and turning it
40:43 an inside signal. This is a called transduction. I'm converting one thing
40:49 something else. And it's through this process where I'm gonna activate some sort
40:55 response inside the cell. So the molecule binds your receptor series of molecules
41:03 turned on and I get a response a result. All right,
41:10 when I'm talking about a response, can be both an inactivation or an
41:15 . So I might be turning on , I might be turning off
41:18 It's usually easier to think in terms turning things on, but that's not
41:21 the case. Now, why you're wondering, do I turn on a
41:27 bunch of molecules? Why can't I turn the thing on that I'm supposed
41:30 be doing? And again, the is is that one signal probably activates
41:34 things at the same time. The thing that we're doing here in this
41:39 of events is we're creating an One molecule might turn on one receptor
41:45 one activated receptor might turn on 10 100 of the molecules downstream. And
41:51 molecule for each one of its, turned on, might turn on 10
41:54 100 or 1000 molecules which might turn 10 to 100 to 1000 molecules.
41:59 so what starts off as something that a single itsy bitsy teeny tiny molecule
42:04 turned into a massive response inside the . This is what a transduction cascade
42:13 looks like basically activation, activation, . And what this is trying to
42:18 you is just one response. What doesn't show you is that this activated
42:23 may not just be turning on triangle might be turning on another molecule and
42:29 molecule might be turning on three So what I'm saying is that it's
42:34 not a linear path, like what seeing here, it's actually a path
42:39 expands outward. Did that kind of sense? Right? So multiple systems
42:47 being activated and inactivated simultaneously to create change in the cell. Now,
42:57 guys probably don't understand this just But for something happens when you become
43:01 adult is that the cost of electricity really, really angering to you.
43:09 right. And so like when you into a room that has a light
43:13 on, you get really mad and curse your Children and then you turn
43:18 the light and then you go into other room and then you find that
43:20 lights turned on, you do the thing over and over again. All
43:24 . Now, I don't know where comes from, but I think it
43:26 to do with what happens inside the . It's very molecular, right?
43:31 whenever you turn anything on, you just leave it on, right?
43:36 that means the system would stay on you want something to be activated and
43:40 do its thing and then you want to turn back off. And so
43:44 our cells and in our bodies, every system that gets turned on,
43:48 a mechanism to turn it right back . All these we refer to as
43:52 switches. And this example is not great one. It's just one that
43:56 saw. I think in your So I just used it. But
43:59 idea here is that we have a , right? So here's our
44:05 it's stays in its inactive state and it becomes activated, right? So
44:11 basically gonna be going through this cycle , right? So it goes
44:16 And if I didn't turn it then this whatever this is turning on
44:19 gonna cause problems. So what we is we have molecules that sit in
44:24 that do the opposite. So if turned it on, so this,
44:28 system right here turns it on, almost immediately we have a system that
44:31 it right back off again. So we've modernized, I don't know if
44:38 done this in your household, maybe parents did. But like there are
44:42 that just turn on and turn When you walk into the room,
44:46 had to do that with my daughter's because she always left the bathroom light
44:49 . I was five years old, years old. I just, it's
44:54 switch just she never did. So finally just so she walks in turns
44:59 five minutes later turns off. That's that is an automatic system so
45:05 So good. All right. So each of these cases, or
45:09 in the example that we just showed , we have a cell that binds
45:12 a surface receptor that turns on a . There's another type of system which
45:19 also a type of signaling and it's to what we've already learned about.
45:24 , hey, if I have a , all I gotta do is open
45:27 the channel. When I open up channel I get ions flowing into the
45:30 . And that change in the ion can cause a change in the activity
45:35 the cell. This is how your work. Basically, I open up
45:38 channel ions flow in I create electrical that then travels through the cell.
45:42 whenever ions are involved directly, we to this as ionotropic. So,
45:49 is chemical binding. A receptor ionotropic opening up a channel ions flowing through
45:54 changes in the cell. All Now, these are gonna be
45:57 very short lived. These take a . Now, why do they take
46:01 while? Because I got multiple steps the way. So they last
46:07 All right. But there's something that even longer than these two. And
46:11 the third type of signaling and it's nuclear receptor signaling, which sounds really
46:17 . All right. So we have nucleus inside the cell. So if
46:22 have a nuclear receptor, where do think the receptor belongs in the
46:29 Yeah. So the truth is is a nuclear receptor acts inside the
46:34 it can be found both in the or in the nucleus, it kind
46:37 moves back and forth between the But in this particular case, we
46:42 have a molecule that is not All right. So, hydrophilic lacks
46:47 . In this case, it's a , it doesn't want to be in
46:52 . And so what it does is it, it's capable of passing through
46:56 plasma membrane without any sort of And so what it's doing is it's
47:01 to get away from water as best it can. So its receptors are
47:05 inside the cell and when that receptor up to that hormone, that
47:12 what it's gonna do is it trans it relocates itself into the nucleus.
47:18 what we're gonna do here is that nuclear receptor with its ligand will now
47:24 on DNA directly. All right. , in this little picture, they
47:28 abbreviation and stuff. So it's just nuclear receptor. Uh an HR E
47:33 just a region on DNA that says is where that nuclear receptor binds.
47:37 a hormone response element. And what basically saying is when this molecule comes
47:42 binds here, it helps to change expression. That means it turns on
47:47 or it turns off genes and we're gonna define which one it's doing.
47:50 just, it's gonna be uh gene . All right. So these types
47:56 hormones turn on genes and when I on a gene, for example,
48:01 am I doing? I'm making new . All right. And that new
48:06 now is gonna cause changes in the of the cell now to distinguish this
48:11 quickly between me about uh metabotropic uh signaling. If I walked into a
48:16 and I wanna make it bright, do I do? As I go
48:19 to the light switch and I flick switch, right. I have created
48:23 activity that causes change, which is the all the machinery is all up
48:28 in the walls. All the wires on the walls, the lights turn
48:31 , right. So, metabotropic, machinery you need is already there.
48:34 I gotta do is flip the switch you're dealing with nuclear receptor. If
48:40 were, if you were to use same sort of analogy, if I
48:42 to turn on the lights in the , I have to build the
48:46 I have to put the wires I have to put the lights in
48:49 then they get turned on. All . So it's a longer process,
48:54 it's a process that then lasts All right, it sticks around for
49:00 longer period of time. So it's , it's particularly uh short, but
49:07 we're doing is we're changing what the is doing in the long term.
49:12 just are you, are you secreting or not secreting something? That sort
49:17 thing? So, yes, That's a good, I, I'm
49:22 I saw a hand up for this . OK. Very good question.
49:27 are we using this type of All right. If you look very
49:30 up here. It says hormone, example, a steroid. All
49:36 Now, your signaling molecules are gonna in one of two flavors. All
49:40 . Flavor number one is that it hydrophilic, it is a protein that
49:46 to hang out in the water Number two is gonna be a
49:51 So this is when we go back look at those slides of the mo
49:54 biomolecules. That thing when we're talking lipids and I had that little chart
49:58 all the steroids. I said, memorize this, please still don't go
50:02 it. But if you go look all those things, you'll see.
50:04 , these are all fats, those , all those lipophilic hormones are gonna
50:09 the ones that use this. So as an example, estrogen,
50:14 progesterone, aldosterone cortisol, I think got them all. Um I,
50:19 , I'm missing one. I'm not remember off the top of my
50:24 but those are the ones that use sort of me methodology. All
50:28 there's a lot of other hormones that none of them are gonna hit,
50:31 like follicle stimulating hormone, growth um adrenaline, all right, dopamine
50:39 , these things are gonna work in metabotropic mechanism. They like to hang
50:44 in water. So they bind to receptors. All right. So different
50:51 for different types of molecules so So good. All right. Are
50:57 ready to wrap everything up and start back out to the surface of the
51:02 because this stuff is like, you , itsy bitsy and hard to visualize
51:09 other questions about self signaling. So goal here right now is to introduce
51:14 to some ideas. All right, what we're gonna do is we're gonna
51:17 these ideas forward as we're moving through systems and asking the questions. All
51:21 . So how is this working? do, how does this, how
51:24 this system talk to other things? really what the goal is here.
51:29 I'm not gonna say, give me example of because you don't know any
51:34 yet, right? All right. the last little bit here is,
51:38 right. So cells with all these , parts that we've been talking about
51:43 the ability to talk to each other grouped together and they form structures called
51:49 . So how do the tissues What holds them all together? And
51:53 thing that really holds them together are specialized junctions in between the cells.
51:57 there are different types you can see . These are a list of the
52:01 types. Actually, when again, when I was in college, these
52:04 exist, everything was presumed tight And then they started recognizing that some
52:08 the tight junctions were different and that's the adherence junctions came up, but
52:14 very similar. But what we're gonna is we're just gonna walk through them
52:17 right. So the first type is desmosome. And so here in a
52:22 , what we have is we have whole bunch of intermediate filaments that are
52:25 with a plaque of proteins. So can think of it like this.
52:28 like taking a wire, attaching it an anchor and then the anchor is
52:33 in cement. All right. So kind of what this is like,
52:36 is like the cement and we're anchored it with all these wires. And
52:40 what we're gonna do is this is cell and we have the same stuff
52:44 the other cell. And so on side of that plaque is you have
52:49 that are in direct contact with each and holding on to each other.
52:53 right. So they're in direct And what you now have is you
52:57 a very, very strong structure. if I start pulling on these intermediate
53:02 , that force gets distributed throughout that plaque, and then that force is
53:08 directed across the cell to the other and then it's dispersed through that plaque
53:13 then it's distributed along the uh the of those intermediate filaments. And so
53:18 we've now done is we've created an so that stress forces can be distributed
53:23 a group of cells instead of a cell, right? And this provides
53:28 mechanical stability between your cells. So , going back to the Indian burn
53:32 you grab somebody's arm and try to their skin off. It doesn't come
53:36 off because all the cells are connected each other via these types of
53:42 This is a terrible picture but it that sort of that type of relationship
53:46 the cells because you don't have this of space. But do you see
53:49 we've done here? That would be desmosome, a Desmon Zoe, a
53:52 zone. Look how many de and is a cartoon, right? But
53:55 trying to show you is like, how many interactions. So if I
53:59 on this cell, it's gonna be , not just to this cell but
54:03 all the cells that surround it and to all the cells that surround those
54:06 so on and so on and so and this disperses the forces.
54:12 So characteristics, plaque, intermediate filaments with another cell through a bunch of
54:19 adhesion molecules that attach it to another zone. Half of a desmosome would
54:25 a hemi desma zone. Chey's All right. Now here, very
54:32 . The difference is is that I have cells surrounding everything. So for
54:38 , if you go into your you're gonna get down to the last
54:41 ce uh skin cell, which is epithelial cell and it's gonna be lying
54:45 top of a type of tissue called tissue. So there is no cell
54:50 . It's just a bunch of proteins another and, and loose uh cells
54:55 are affiliated in this matrix. So do I attach to a matrix when
55:00 not cells everywhere? Well, I my half desmosome and I insert those
55:06 adhesion molecules and they bind up to that are found in the connective
55:13 And so this is how your skin on the surface of the connective
55:18 Now, we're gonna do something here little bit gross. But I think
55:22 , you're, you're, you can it. Have you ever had to
55:26 the skin off of chicken? Like you're cooking, right? And if
55:30 notice when you start tearing it you can see that there's this thin
55:34 of white stuff that's not fat because fat is gross and yellow and icky
55:38 gross and the dog will eat If you just throw it like in
55:40 air, you'll catch it. You that. But what you can do
55:43 you can take your finger between the muscle and the skin and you
55:47 just run it through there, But that thing that's holding that skin
55:51 that you're tearing with your finger that the hemidesmosome, holding the skin down
55:58 that little white layer of connective If we skinned, you, same
56:07 I know that's out you is gonna gross. All right. So that's
56:11 type. Yes, ma'am to another tissue, which is usually gonna be
56:25 tissue. I know if I said always connective tissue, someone would come
56:29 to me. No, no. , usually connective tissue. All
56:34 Now you'll see on the slide. scary names don't memorize the scary
56:38 Those aren't important. It's just adding . All right. Adherent. When
56:45 hear adherent, what's, what's the that you hear? Adhere, stick
56:50 ? Right. And so what you here is another structure that is very
56:55 to the desmosome. All right. has different molecules that are involved,
57:00 right. But it's very similar. here we're using a different type,
57:04 used Integris over here, right? these are Integris again. I
57:07 don't worry about it, but we're a different molecule called c adherents.
57:11 closely related, but they're different. uh you don't use intermediate filaments,
57:18 act in so use micro uh micro . All right. Again, probably
57:24 at me and go well, why I care that they're different molecules?
57:27 , why does it matter? you know, different things, different
57:33 do different things. So where you're dealing with stress, you have less
57:40 than you did when you have an filament. All right. So the
57:45 is much more stiff when you see adherence junction. Have you ever done
57:53 um the Ziploc test? That's where put something and t the zip log
57:57 seal it, turn it upside down shake it. Now, that used
58:01 be their ad, it's like we're than the, the non name
58:05 And so they put spaghetti sauce in and shake it over like a wedding
58:10 . You know, would you do with the inferior bag? No,
58:14 a Ziploc you could. All Why do I mention Ziploc bags?
58:18 because that's what a tight junctions like what it does. And I'm gonna
58:22 you a different picture to help you this. What it does is it
58:26 two cells. You can see I've got a series of proteins on
58:29 cell and a series of proteins on other cell. And they basically come
58:33 and they interlock and what they do they create a seal between the two
58:39 . So we have a junction that now tight and so nothing can pass
58:44 between the two cells. That's the . All right. So passing between
58:50 two cells would be referred to as diffusion. Now, I'm just gonna
58:54 slides so that you can see this little bit better. So here you
58:57 see a series of cells here, don't have the tight junctions. So
59:00 got molecules over here. Look, flow freely between the two cells.
59:04 when I put a tight junction in , those molecules can't go in between
59:09 two cells. Those molecules have to through the cell which would be trans
59:15 movement. All right. Now, other thing that this does, which
59:20 think is really cool and it becomes a little bit later is that while
59:25 see these proteins here on the they, they actually create a meshwork
59:31 other proteins inside the cell so that create two distinct areas inside the
59:37 And you may create two distinct environments the outside of the cell. So
59:42 you're looking at here is epithelium. is a type of tissue that allows
59:47 secretion and absorption. So if I'm something, I'm pulling things into the
59:52 and then I'm gonna allow them to into the body. And so that
59:57 all the molecules on the surface on side are involved in absorbing those materials
60:02 secreting in uh materials. Whereas the on that side are gonna be
60:06 So I create polarity. So tight don't just serve as creating a a
60:14 between cells. It creates unique environments either side of those tight junctions,
60:19 creates a polarity for them. And is really important when it comes to
60:26 cells. Gab junctions. Here we again, all right, gap junctions
60:36 actually pretty basic. You can see here's cell number one, cell number
60:40 side of the cell has these they're called connections because they connect the
60:46 together. There's a whole bunch of types of them. I think there's
60:51 20 different varieties of connections, but can see what they do is you
60:55 six of them. 123456, they exist in a closed state or an
60:59 state. But what they do is create a channel in between the two
61:02 . So this is how I can ions in very small molecules and allow
61:06 that type of juxtaposition signaling. All , the juxta signaling that's occurring.
61:12 right. So there's a better picture that. How many slides to
61:22 Are you counting? If I was your seats, I'd be counting.
61:25 like 03 more to go. There's three. Is it three,
61:30 ? OK. I'm so sorry. better talk faster. All right.
61:35 , what I want you to do I want you to envision cells are
61:38 bald, all cells are incredibly busy covered with all sorts of molecules.
61:46 if you've gone back and you've watched video that I linked to on
61:49 you get a sense of that. video is showing you a neutrophil invading
61:54 blood wall or the, the blood wall, the endothelium and moving to
62:00 side of, of tissue damage. it's showing you how all this machinery
62:04 getting turned on and off. But of the things that it shows you
62:08 how those receptors are actually moved to surface of the cell and it shows
62:13 something looks a lot like this. for those of you who've seen the
62:17 does did the video kind of indicate that busy for the rest of you
62:22 haven't watched the video? Are you of encouraged to go watch it
62:25 Yeah, I'm telling you, you know, eight minutes of your
62:28 and it gives you a frame of , a vi a visual frame of
62:32 . And so what you can see is on the outside of the
62:35 that's the extracellular matrix inside of the . That's where the side of skeleton
62:40 . You can see the integral you can see the uh the sugar
62:44 that are coming off. So you're the glyco Cali down here, but
62:48 is not just empty up there. are proteins and other molecules that are
62:54 outside that create a barrier or an environment for that cell. All
63:01 this is gonna be secreted by the . All right is these just don't
63:05 show up there's all sorts of And again, these molecules, the
63:09 aren't so important for you guys. my upper level students, they'd be
63:13 OK, I've got to know these but what they do is they allow
63:18 unique interactions. So when we're talking the direct interactions that are happening between
63:23 , it's usually because of molecules that here on the surface, but they
63:27 to penetrate and pass through this extracellular . It allows cells to be anchored
63:33 very specific locations. The other thing it does, it allows you to
63:38 not just with other cells, but the environment surrounding the cell. So
63:45 is very, very busy outside the . And when you hear extracellular matrix
63:51 think tons of proteins doing stuff last bit here and we might even get
63:58 early if I shut up. You're like, yes, please shut
64:02 . All right. It's very easy wanna dive deep into mitosis. All
64:09 , mitosis is the mechanism by which replicate themselves. And what you're looking
64:14 is the cell cycle. You've probably it at least three times in your
64:17 at this point. Does that sound right? OK. So I just
64:22 to kind of define some stuff for . All right, you're familiar with
64:26 . All right, we have a a period of time in which we
64:29 preparing for division. So this is normal cell life that's going on.
64:33 then what happens is, is OK, time to divide. So
64:36 gonna make the machinery we need to to divide. And then we have
64:39 period of cell division where we create , a, an act, an
64:43 replica of the cell that we started . So we start with a mother
64:47 and we create two daughter cells and daughter. Basically, what you've done
64:50 you've just separated everything out here. those two phases, we have the
64:55 that is the metabolic and growth That is the part where you are
64:59 for division. So you're doing your activity. Oh, it's time to
65:03 . Let's get ready to divide and you enter into mitosis, mitosis is
65:07 division portion. All right. So dividing the cell and the nuclear
65:13 Now, if this were a general or an intro bio class or a
65:17 biology class, we'd go into more about this. I have this up
65:21 . So I just, we're just . All right. So the idea
65:24 is there are some sub phases when see a G, that's a growth
65:29 . All right, G stands for or gap. So if you have
65:33 G zero, that is a period the cell has exited out of the
65:38 of DNA replication, it's no longer . That doesn't mean it will never
65:43 again. It just means I'm focused doing what my job is. All
65:47 . So I can enter back into phase and go through the other
65:53 So the other stages include G one G two. So this is why
65:56 refer to them as growth. They variable length, things are able to
66:00 kind of do their, do their . But then between the two
66:04 we have a period of time where like, OK, we need to
66:08 for that division. So we're gonna that DNA that we have and we're
66:11 make an exact replica. So this the synthesis phase. That's why it
66:15 with an S, all right. I'm making DNA. So the G
66:21 while it's a growth phase, what also is, it's making sure that
66:25 DNA that I made is ready to into replication. If you screw that
66:29 , you're gonna screw the cell So it's not gonna let you
66:33 So there are specifics uh checkpoints that in both the G one and in
66:38 G two to ensure that you're ready progress forward into that phase,
66:42 We don't wanna lose a chromosome. that make sense? Right. We
66:46 make sure we copied things correctly. don't wanna copy homework badly,
66:52 Because then you're gonna get all your wrong. If you're gonna copy your
66:56 , make sure you do a good . Don't copy your homework. All
67:00 . So with that in mind, is the metabolic phases. The synthesis
67:06 , synthesis of DNA. Before I into replication, mitosis is the phase
67:14 we're actually dividing up the nuclear material dividing up the uh cell itself.
67:20 right. Now, you've all learned , I'm sure you probably learned I
67:24 interphase which is the outside phase and prophase metaphase, anaphase stela. Y'all
67:29 that. No. OK. just tattoo it to your body.
67:33 are things I'm gonna say if if you're a tattoo person, this
67:36 just something you tattoo to your IP mat prophase, metaphase,
67:40 telophase. All right. And I keep it simple in prophase. What
67:45 doing is you're starting to see the membrane or the nuclear membrane breaking down
67:50 you're starting to see the aggregation of DNA. So remember how he said
67:54 DNA is like a bunch of loose and then what's gonna happen is that
67:58 begins to condense down and make those tiny X's that we think about when
68:02 think about DNA. All right. those are the chromosomes. So it's
68:06 condensation and getting ready for division in . What you're gonna do is you're
68:10 line up those chromosomes in the middle the cell. Notice what we also
68:14 is we see the s the, material inside the cell is being divided
68:19 either side of the cell. All . But what we're doing is we're
68:23 pre prepared for that actual division. uh So I said anaphase, I
68:28 metaphase. So I mat P MA anaphase is when we divide everything
68:33 So the nuclear material goes to the sides and then telophase. What we're
68:38 do is we're now reorganizing the new and we're gonna start seeing the process
68:43 cytokinesis. Cytokinesis is a fancy word saying, cell division, cell breaking
68:51 . And what you're doing is you're an invisible lasso and you're putting it
68:55 the middle of the cell after the material is separated and you're now tightening
68:58 the lasso and squeezing that one cell two. So that's what you're seeing
69:05 the cytokinesis. There we go. that's the cleavage furrow. So I
69:13 you, you might get one question the exam that simply just says,
69:16 , do you know what prophase Do you know what metaphase anaphase
69:19 What is cytokinesis? I'm not gonna you to draw or identify because if
69:26 want to take biology one again, have you do that. Ok.
69:32 in order to become the organism that are, your cells had to go
69:38 thousands and thousands and thousands of mitotic , you began life as one cell
69:46 now you are billions. All With that, we have one more
69:54 before the exam just so, you , the exam covers everything in the
69:58 lectures up to that point. Did all see the announcement about CASA?
70:03 you haven't gotten your biometric done, it done before, let's just say
70:09 . Next week you have problems with to log into CASA. Make sure
70:13 logging into canvas, not the CASA . You weren't the first, you
70:20 the
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