| 00:11 | Testing, testing, testing. Hurry . Ok, folks. Happy |
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| 00:20 | Um All right, usual stuff. , let's see. So we're doing |
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| 00:30 | chapter 10. This is the last we'll cover before the exam. |
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| 00:37 | next week. Uh, we start last unit. Ok. So it's |
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| 00:41 | about, um, immune system et cetera. Uh I haven't put |
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| 00:49 | , I haven't opened it yet but do that before the end of the |
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| 00:52 | . Um, that material. um, and we'll finish everything this |
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| 01:00 | . I don't, I don't see being any carryover. So, |
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| 01:04 | so they is kind of just going will end, will end at the |
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| 01:10 | of the trip to Fan Arron. cover like the part one of that |
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| 01:14 | then do the rest of the stuff Thursday. Uh Let's see. |
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| 01:18 | you know, quiz, remember those gonna be a little more comprehensive, |
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| 01:22 | ? So it's gonna cover seven through . Uh, remember that, you |
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| 01:27 | , stick to that, you whatever you use as your source to |
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| 01:33 | you read the book, right? you don't read the book, then |
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| 01:35 | doesn't matter. But, uh, you read the book, um, |
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| 01:39 | you know, I'm not covering the of any of these chapters, |
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| 01:44 | So use that to keep on track the uh the exam review sheet or |
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| 01:49 | lecture notes. Just remember that. remember that over there and that I'm |
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| 01:55 | covering all the chapters in their Ok. So, um, you |
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| 02:00 | want to waste time going over stuff not relevant? Ok. Um |
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| 02:06 | what else? So exam three schedule already opened and uh there's a smart |
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| 02:11 | . I think the Chapter 10 smart is due next Monday. So, |
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| 02:15 | right. Uh, once I was to uh mention this, so, |
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| 02:22 | , if you are one and I many of you are interested in |
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| 02:29 | in uh professional school, right? school, et cetera, right? |
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| 02:36 | you will, and I know the is hard, you can see it |
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| 02:39 | , but I'll post it on canvas you can have access to it |
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| 02:44 | She's a Doctor Ogletree has been offering for several semesters. Um And uh |
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| 02:51 | basically it's, if you're interested in professional healthcare profession, right? How |
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| 02:57 | get into their, into the, it's optometry or medical school, |
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| 03:01 | whatever it's, how do you do ? Um, there'll be people coming |
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| 03:07 | from these professions to enlighten you, assume on the process and what it's |
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| 03:12 | about. So, you know, , it's there, it's a one |
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| 03:16 | course in the spring. So you know, ok, and So |
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| 03:22 | , I'll, I'll again, I'll this on canvas as well so you |
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| 03:25 | look at it. So. All . So what everybody, so I'm |
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| 03:28 | to see. Ok. So did win the Halloween contest? Well, |
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| 03:38 | it was hottest Ken. It was and Barbie. Right? So it |
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| 03:41 | a couple, they changed it So it was best Ken and |
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| 03:44 | whether you were a couple or I had nothing to do. So |
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| 03:47 | I win? Of course, I . Oh, so just think. |
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| 03:55 | , ladies calm down. So here's , here's a close up. It |
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| 04:01 | abs man. And if you think real, it's, it's not. |
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| 04:07 | it's actually a shirt but that was . I have the, the shirt |
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| 04:11 | , wow, ok. Plus the lighting that probably helped you. So |
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| 04:15 | but the, the way, So, uh anyway, so I |
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| 04:21 | . Ok. Um And that was uh that, and that's not my |
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| 04:25 | , by the way. Um She's better looking but she, she is |
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| 04:32 | this is uh that was the Barbie . So Cowboy Barbie. OK. |
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| 04:37 | , um anyway, so enough of OK. Uh uh gene regulation. |
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| 04:46 | we are going to go into today kind of the terminology used the levels |
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| 04:53 | control and then the specific examples. specifics in terms of La Opera, |
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| 05:01 | Fan Operon and then uh some kind different um aspects of control. We'll |
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| 05:09 | on that over that Thursday. So, uh I think it helps |
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| 05:15 | the, with both of these Uh there's animations, uh I think |
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| 05:19 | helps to view those. You can kind of a picture of what's going |
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| 05:23 | . Um It's not that complicated but is the, you're gonna have to |
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| 05:30 | la opera and Tripen opera and there differences there obviously. So you wanna |
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| 05:36 | able to compare and contrast those OK. Um In terms of the |
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| 05:41 | when the control happens and when it , OK. So, um so |
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| 05:48 | before we get there, we'll go LAC Operon today. OK. And |
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| 05:53 | , uh I'm sure um we used cover an intro bio, we used |
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| 05:59 | cover Lac Opera. We don't do anymore. Um That's been for several |
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| 06:04 | now. But so I don't, but I'm pretty sure has anybody had |
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| 06:09 | Opera near the courses yet? It it uh Biochemistry. Genetics. |
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| 06:14 | OK. Did you go into uh I'm sure you went into the |
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| 06:21 | the um what is it? There the, you have the, |
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| 06:26 | the absence of the presence of lactose it, but then also the glucose |
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| 06:31 | you went through all that. All . Well, then your expert, |
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| 06:34 | ? So, um the o on did it up. OK. Uh |
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| 06:40 | right, then maybe just if you that, then uh you can help |
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| 06:43 | others that have. How about So, um and probably it's likely |
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| 06:49 | get it more than that, you biochemistry and some other upper level bio |
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| 06:52 | , you'll probably see it again and sick of it by the time. |
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| 06:55 | if you're not already. OK. Anyway, so let's start here. |
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| 07:02 | . So kind of the basics, ? So here's let me open this |
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| 07:06 | . Um OK. So we have question, the internal response in the |
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| 07:14 | turns into an output action uh by cell due to the formation and functioning |
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| 07:24 | . So you have some kind of , the what the cell does about |
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| 07:30 | is typically through these things. Usually most of the time. |
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| 07:57 | OK. That, hey two let's count down from seven oh |
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| 08:14 | 654 21. OK. Point it's protein or proteins. OK? |
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| 08:24 | could be uh sometimes it can be RN A molecules um but usually it's |
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| 08:29 | be action of a protein subtype. . Um And so of course, |
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| 08:34 | gets us into the um regulation, ? So a an output as as |
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| 08:45 | in the previous slide occurs as a of some kind of something going on |
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| 08:50 | the cell, environmental or whatever nutrients present. Um What's the temperature? |
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| 08:56 | oxygen levels are concentration, these are things, you can probably list a |
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| 09:01 | more of what a bacterial cell would to respond to in its environment, |
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| 09:06 | ? And so you can't just sit do nothing or likely won't survive. |
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| 09:11 | you have to turn off and on genes, right, to uh |
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| 09:16 | to have a response. And so about controlling these things, right? |
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| 09:21 | , external signals um are um converted some kind of sensor protein on the |
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| 09:30 | . Uh This could be a receptor some type. It could be a |
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| 09:35 | of lactose operon. It's a, a transport protein. So it could |
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| 09:39 | a number of different things. But any case, it's, it's, |
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| 09:44 | senses what's going on through that and internally typically through expression of transcription |
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| 09:52 | maybe activators, et cetera, uh factor involved in this right to, |
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| 09:59 | turn on various genes, right? , um and that, of |
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| 10:05 | so remember what bacterial cells are we got the operon structure. |
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| 10:10 | And so the ultimately producing a protein some sort. OK. And so |
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| 10:19 | now the uh question here. So did uh I meant to show you |
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| 10:25 | . So I uh looking today so of a Halloween theme and related to |
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| 10:31 | regulation what they call zombie genes. . And I didn't know this myself |
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| 10:39 | uh um you or, or you're a living, those that are in |
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| 10:44 | living state like we are now, ? You're obviously, you're expressing |
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| 10:47 | controlling genes, different types when you longer cease to exist. You actually |
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| 10:55 | expressing genes. I didn't know that called a, you call it a |
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| 11:00 | it was a Greek. Greek term fan NAO transcriptome, which means the |
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| 11:06 | part has a Greek for dead So like you're dead, your transcriptome |
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| 11:10 | you are dead, you actually, actually produce um express some genes there |
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| 11:18 | uh like 2% or something like that , of the genome expressed. So |
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| 11:21 | thought that was, that's crazy. And it, and it relates to |
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| 11:25 | the cells, it's like this like response by your cells to say, |
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| 11:29 | , we're not ready to die So we're gonna still do some expression |
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| 11:33 | . OK. So I thought that uh interesting, but I'll, |
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| 11:38 | I'll post the article, you may interested in that. Um Anyway, |
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| 11:42 | on track here, right? So all about controlling genes, right? |
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| 11:45 | remember, and I've said this a times this semester you can ever see |
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| 11:50 | this process here. That is all energy required, right? Requires |
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| 11:56 | to do this, to make a to transcribe, right? All these |
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| 12:00 | are building processes, takes energy. of course, you gotta control |
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| 12:04 | You can't just be willy nilly, in genes when you don't need to |
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| 12:08 | you're wasting energy. OK? So is tightly controlled and again, based |
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| 12:13 | what's going on around it, what's on inside of it, all |
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| 12:16 | to kind of uh modulate things. ? Um So levels of control. |
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| 12:24 | that's what this question relates about. . So that's why I mentioned earlier |
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| 12:28 | know the basics of, you DNA RN A protein, right? |
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| 12:32 | that's, that's how we're gonna control process at those various levels. |
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| 12:38 | So here we've got C tryptophan Operon , right? Can be controlled by |
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| 12:44 | Thehan itself, right? So that is one that um the, it's |
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| 12:52 | opera on, that is an anabolic . It controls the expression, the |
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| 12:57 | of Crypt fan. That's what the of the opera and do make |
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| 13:01 | OK. So one level of control a trip define that's made can inhibit |
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| 13:06 | of the enzymes that helps to make . OK. And so what kind |
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| 13:12 | what we, what do we call kind of control? OK. |
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| 13:26 | OK. Let's count down from So I did um I added a |
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| 13:32 | to this and I made it before . Um Obviously, I'll post it |
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| 13:37 | class but it, it's helped to of help you organize this um levels |
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| 13:41 | control. OK. Mm All So see, we got transcriptional, |
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| 13:58 | translational uh translational. So uh if answered e you're correct. OK. |
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| 14:11 | uh I'll explain, explain on this . OK. So um this one |
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| 14:16 | the next one. So multiple right? So DNA um you can |
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| 14:23 | nucleotides that can um that can uh expression uh like methyl cyto, for |
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| 14:31 | , OK. We'll look at, look at this Thursday, this thing |
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| 14:35 | phase variation where you're basically just like flopping DNA segments, inverting them and |
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| 14:42 | that alters transcription. OK. And a way to control, um RN |
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| 14:50 | , right? So you go from to RN A to proteins, |
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| 14:53 | So at the RN A level, multiple. OK. And one of |
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| 14:58 | is transcription, very common method of in prokaryotes is transcriptional control. |
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| 15:05 | So, so, but what it people often confuse this. OK. |
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| 15:11 | transcriptional control is deals with not, the fully formed transcript. It's before |
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| 15:21 | right? It's are we going to transcription or not? Right. So |
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| 15:26 | affecting the ability of the army pli to do its function, right? |
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| 15:32 | you either allow it or you That's transcriptional control, right? And |
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| 15:35 | what black operan will look at um defend OPERON. These are all transcriptional |
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| 15:42 | . OK. Um RN A OK. So um that has to |
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| 15:51 | with kind of think of it as half life, right? MRN |
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| 15:54 | So uh Mrnas are in the order seconds. OK. And uh or |
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| 16:01 | maybe, but not much longer, ? Compared to periodic transcripts, which |
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| 16:05 | be um on your order of hours days or even months, sometimes. |
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| 16:11 | . So there's different ways you can that um translational control, right? |
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| 16:16 | anything to do with the ribosome? you allowing the ribosome to function or |
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| 16:20 | ? OK. Uh posttranslational. So was the answer to the question, |
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| 16:25 | ? So here you've now made the if you're posttranslational. So you can |
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| 16:31 | affect expression, right? You can the proteins, you can add a |
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| 16:36 | group to it and activate it, ? Or maybe that will deactivate, |
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| 16:41 | . So there's different things you can at that level, it can act |
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| 16:45 | as a crypto fan. This can bind to an enzyme. Remember the |
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| 16:50 | uh we call allosteric right? Uh between with enzymes. So it can |
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| 16:56 | to an enzyme, right? And it. OK. So uh so |
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| 17:01 | these uh can happen and they can it, it's not just one happens |
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| 17:07 | that's it. They can all they all they all combine with each |
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| 17:10 | . OK. So the the slide see here is the one I made |
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| 17:14 | for class right now. Oh Let back up. All right. So |
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| 17:18 | is an important concept here. constitutive genes. So everything we just |
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| 17:23 | about here, post translational translational, cetera. Those are all ways to |
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| 17:29 | various genes. But there are some are always expressed and constitutive is what |
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| 17:34 | refers to a cons constitutive gene is much always expressed. OK? And |
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| 17:41 | are gonna be for things like critical type activities. Um you know, |
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| 17:49 | , certain metabolism, genes like maybe or, or, or |
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| 17:54 | Um uh These are functions that are always need to be going. And |
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| 17:59 | genes for that are, are pretty always expressed. OK? So what |
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| 18:03 | call another term, you might see call is what they call housekeeping |
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| 18:08 | right? Which kind of means what says, right? A housekeeping gene |
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| 18:11 | one that's always kind of they're needed the, the day to day functioning |
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| 18:16 | the cell if you will like a to minute functioning of the cell. |
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| 18:18 | so those are always on. Uh But you know, in comparatively |
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| 18:24 | , most of these genes and organs gonna be controlled, right? But |
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| 18:28 | do have some that aren't, So, so this is the slide |
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| 18:32 | was talking about. So again, way to kind of interpret this. |
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| 18:37 | . So again, this is pretty explanatory DNA. All right, we |
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| 18:40 | talked about that. Uh transcriptional control affect uh involved as we'll see. |
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| 18:45 | course, the promoter operator because that's only preliminary interaction, right? So |
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| 18:50 | where that's where the action is going occur in terms of affecting its |
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| 18:54 | OK? It could involve Sigma right? So we don't go into |
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| 19:00 | the examples of gene control your book uh because there are several that Sigma |
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| 19:06 | , Sigma factors are effective. So you alter that, remember, that's |
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| 19:10 | , that's what, that's what um that are clima to the promoter. |
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| 19:15 | if you fiddle with the Sigma then obviously you're gonna affect the uh |
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| 19:21 | . OK? Uh posttranscriptional, So that's actually kind of a umbrella |
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| 19:28 | that can actually encompass all three of . OK. So it's a more |
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| 19:34 | term. If you will, you posttranscriptional, it could be one of |
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| 19:38 | three things and you know, if go on, I'm, I |
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| 19:42 | I know you will, you want sell bio or, or more upper |
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| 19:48 | classes and you talk about regulation. , you'll see that term and they |
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| 19:52 | actually refer to one of these three . OK? Because it's, it's |
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| 19:58 | what this means is OK? You've the transcript, OK? Now, |
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| 20:02 | can happen to it? Right. , you can alter stability of |
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| 20:06 | make it go away, degrade You can affect the ability of rhyme |
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| 20:10 | to bind to it. OK? Or if they're bound to it to |
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| 20:15 | make them translate or post translational, ? You go to the protein, |
|
| 20:20 | ? So, um anyway, and we just talked about these two and |
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| 20:26 | , so one thing we'll talk about are regulatory RNAs, right? These |
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| 20:31 | actually affect those stability. You can up degrading the RN A or it |
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| 20:36 | affect the ability to translate it. ? So, um anyway, that's |
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| 20:42 | of the, what's going on Any, any questions about that? |
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| 20:48 | , um so this question, let try and open a pole, an |
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| 20:56 | repressor. So here's, we're gonna some terms, right? Active uh |
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| 21:01 | , inactive repressor, uh activators, et cetera. OK? So an |
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| 21:10 | repressor in transcripts control are in operant . This way um an active repressor |
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| 21:19 | an inactive repressor. OK. And conditions that create, that create those |
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| 21:26 | be completely different, we look at opera. So for example, lactose |
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| 21:32 | could defend opera, both involve active active repressors, but the conditions that |
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| 21:39 | it are completely different. OK. So let's see. We're counting down |
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| 21:48 | 15. OK. I cross OK. An active repressor binds to |
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| 22:12 | operator. Yes, that is OK? Um To derepress means to |
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| 22:24 | the repressor, right? So an repressor basically binds to an operator |
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| 22:31 | and blocks transcription. OK. So eliminates a, it um doesn't require |
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| 22:40 | inducer. An inducer will actually inactivated allows or to carry out its |
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| 22:46 | No, if it's, if if it's doing a, then it |
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| 22:50 | do c but it's not doing either those. OK? And so e |
|
| 22:53 | the only correct answer here. Um So terminology, right? So |
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| 22:59 | terms depression induction, core cursor de , OK. So repress, you |
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| 23:06 | , you, you can, you what that means, right? Repress |
|
| 23:10 | , right? You're shutting him right? Um If you're, if |
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| 23:16 | un repressing them, the word is , right? You're so repressed means |
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| 23:21 | think of it as stopping transcription, repression means to alleviate the repression and |
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| 23:26 | transcription. OK. Induction means to transcription. A corepressor can be involved |
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| 23:37 | the repression action. So if you a corepressor, that means you must |
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| 23:41 | another two things coming together to make active repressor. OK? So we'll |
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| 23:46 | at those in kind of context of pictures here. OK. So there's |
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| 23:51 | gonna be some type of regulatory protein is controlling the gene or genes, |
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| 23:58 | ? Only the opera. OK. so um so in induction slash de |
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| 24:07 | , OK. And so both of promote expression of the gene. |
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| 24:12 | Hence on, OK. So here's example here. So we got um |
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| 24:19 | target gene is repressed. OK. in this scenario, here's the active |
|
| 24:27 | . OK. So, so this all about binding, it's all about |
|
| 24:31 | binding to DNA is what it OK. And so the protein binds |
|
| 24:36 | typically what we'll see, you especially in lack and trip opera on |
|
| 24:40 | is the operator sequence, right? we have a promoter, we got |
|
| 24:43 | operator, right? So the operator kind of where this action is |
|
| 24:47 | OK? Um And so the pressure . Now you have a physical blockage |
|
| 24:54 | RN a flier, right? This all because remember the operators by the |
|
| 24:59 | , right? And so RN a binds promoter but can't get around right |
|
| 25:04 | . It's it's being uh repressed, ? So there's a mask, a |
|
| 25:09 | on it, you can't go OK? But if you have an |
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| 25:13 | right, then it can bind, ? So remember when proteins bind or |
|
| 25:18 | binds a protein, it changes the , right? And so now it |
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| 25:22 | the shape that the repressor is now . OK. And comes off that |
|
| 25:30 | sequence, right? And so you , so the presence of inducer promotes |
|
| 25:36 | . All right. And that's essentially the lack opera is. OK. |
|
| 25:40 | example of that. OK. So the presence of lactose presence of lactose |
|
| 25:48 | expression. Technically not correct. It's a version, a variation called allo |
|
| 25:54 | , but we'll get into that Um So the corepressor repressor that mechanism |
|
| 25:59 | the trip is an example of OK. So um in there, |
|
| 26:06 | have a repressor protein but is in inactive state. OK? Because |
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| 26:16 | it has to bind a repressor excuse me to become an active |
|
| 26:22 | OK? And so in that it can bind to that regulatory |
|
| 26:28 | an operator and B expression. So you can see how um these |
|
| 26:34 | both, well, number one, definition of a active repressor and an |
|
| 26:42 | repressor is the same whether you're talking lac operon crypto opera or whatever |
|
| 26:49 | right? But the conditions that create can be completely different and you can |
|
| 26:55 | that here. So here's an active protein in this scenario, right? |
|
| 27:01 | the active one here is complex with corepressor. OK. So the presence |
|
| 27:11 | the corepressor is what forms the active , the presence of an inducer is |
|
| 27:20 | forms the inactive complex. So it's . OK. In terms of creating |
|
| 27:25 | two scenarios OK. But the, the meaning, right? That meaning |
|
| 27:30 | still the same an active repressor in scenarios, both examples um blocks |
|
| 27:39 | right? So active oxy, Active blocks it but it just how |
|
| 27:48 | both become active is completely different. ? Same with inactive. OK. |
|
| 27:56 | um but again, we're uh repeat as we get into the specific examples |
|
| 28:04 | each opera. OK. Um But questions about that, OK. So |
|
| 28:10 | , repression, repression, induction, . Um let's look at this. |
|
| 28:18 | activator. So activators can be a of the scenario. We'll see that |
|
| 28:23 | the uh lactose opera. So uh having the presence of lactose alone and |
|
| 28:31 | absence of glucose. Oh I'm the presence of weo alone isn't |
|
| 28:37 | There's, there's more to it as see. And actually what happens is |
|
| 28:41 | form uh an activator. OK. this kind of goes back to, |
|
| 28:46 | talked about last time and promoter OK? So the or lyra binds |
|
| 28:53 | a promoter and you can get right? Remember that level of expression |
|
| 28:59 | kind of down here. OK. to ramp it up, right? |
|
| 29:05 | , you put components on the promoter that helps to draw the pliers there |
|
| 29:11 | bind it very tightly. OK? you add things like transcriptional activators and |
|
| 29:17 | come bind at the promoter and that to tighter binding of the plum rights |
|
| 29:23 | more expression. OK? What we high level expression? So, Um |
|
| 29:29 | that's what activators do. OK. It can be multiple of them coming |
|
| 29:35 | the promoter that's common for eu periodic . Um Bacteria aren't generally that as |
|
| 29:43 | , but they can certainly have the of activators to enhance the promoter um |
|
| 29:51 | for the prelimerase. OK. Um , the um let's look at |
|
| 29:59 | So we're gonna get into the LA on here and we'll see exam, |
|
| 30:02 | gonna see examples of everything we just about repressor, uh inducer, et |
|
| 30:07 | . OK. So here uh which true about the lack opera. |
|
| 30:16 | So I give you some time to that Mr OK. And mm mhm |
|
| 31:06 | . OK. OK. Let's count from 10 sh sh sh Right? |
|
| 31:26 | It is B OK. So I think it helps to because when |
|
| 31:32 | compare and contrast la opera, hip and kind of the logic behind the |
|
| 31:38 | of those, it helps to remember both operas are for opposite pathways. |
|
| 31:48 | other words, La Opera is a bolic pathway. It's about the steps |
|
| 31:54 | break down lactose. So we can it as an energy source. Tryptophan |
|
| 31:58 | is a anabolic bio synthetic pathway. about making tryptophan, right? So |
|
| 32:05 | different things obviously. So uh so Operon, so obviously, that's |
|
| 32:11 | It's for the breakdown of lactose, the synthesis. OK. Um It's |
|
| 32:19 | example of transcriptional control, not OK. Because the end result |
|
| 32:27 | are we going to form the transcript not. OK. Um And this |
|
| 32:33 | inactive repressor. No, uh that's . Uh An inactive lack repressor |
|
| 32:40 | not, not prevents OK. La on expression. OK. So B |
|
| 32:46 | the only correct one because lack Y that transport protein for lactose, |
|
| 32:52 | it binds to it and brings it the cell. OK. And essentially |
|
| 32:57 | black Y is kind of the eyeballs lactose like the cell will only know |
|
| 33:02 | lactose is out there, if it that protein in its membrane. |
|
| 33:08 | Um OK. So here are the . So uh so la opera, |
|
| 33:17 | ? So we have a regulatory gene from the black opera, which is |
|
| 33:22 | genes, three proteins, but we need to worry about this one black |
|
| 33:30 | . OK. Zoy is all that us. Uh It's still not known |
|
| 33:36 | what the A product does for the . OK. This can be completely |
|
| 33:43 | , this is gonna be completely knocked and still the cell is completely capable |
|
| 33:49 | taking a lactose and using it. it has nothing to do apparently with |
|
| 33:53 | metabolism. So nothing to worry about . OK. So number one |
|
| 33:59 | is the bullet point you see OK. A low level always occurs |
|
| 34:04 | there's a reason for that. And low, I mean like one |
|
| 34:08 | two molecules worth OK. So nothing meaningful for the cell in terms of |
|
| 34:15 | lactose obviously. But, but it to generate this one here. |
|
| 34:20 | the why? Right. This So um because that's the way you |
|
| 34:27 | see if lactose is even present. gotta have that or else it |
|
| 34:31 | it, you know, it won't what's out there to, to be |
|
| 34:34 | to do anything if it needs to it. OK. So, so |
|
| 34:39 | there. So the perm, perm another name for transport protein and think |
|
| 34:44 | it as it makes a cell permeable lactose if you will. OK. |
|
| 34:50 | But it binds specifically to it brings in. OK. And the lac |
|
| 34:57 | Z function, OK. So lactose a guy sack, right? |
|
| 35:01 | you have to cleave it into uh and glucose. OK? And when |
|
| 35:08 | do that, it goes into the other function of the enzyme is |
|
| 35:14 | create the AOL lactose inducer, So this is the thing that actually |
|
| 35:19 | a form that does the actual OK? Not lactose itself. |
|
| 35:27 | The um so at high levels of , you get the the function where |
|
| 35:34 | we're breaking apart lactose and then funneling into glycolysis, right? Uh Glucose |
|
| 35:41 | into don't need to know this. glucose six phosphate, I think and |
|
| 35:48 | this has to go another couple steps it can fall into glycolysis. Um |
|
| 35:55 | that's one of the reasons why glucose an effect on glucose kind of overrides |
|
| 36:00 | if it's present. OK? Because is readily assimilated into the cell. |
|
| 36:05 | that's what Glyco is, is geared taking in glucose and bam off you |
|
| 36:11 | other sugars that they can certainly The co I can use 30 different |
|
| 36:17 | so sugars, ok? But it's go through some steps before it can |
|
| 36:23 | into glycolysis. Ok? And that that like lactose, that those sugars |
|
| 36:30 | they're present and glucose is present, is preferred because it's easily into the |
|
| 36:37 | , takes less energy to get it the pathway. Um lactose and other |
|
| 36:43 | have to be a little more OK. So just keep that in |
|
| 36:47 | back of your head when we when we get there. Um |
|
| 36:52 | So um so really, it's about is why we have to have a |
|
| 37:00 | level of expression. OK? Um that's the eyeballs for the cell to |
|
| 37:07 | glucose lactose. OK? And that's of what we're seeing here. |
|
| 37:12 | So a low level of expression and , I mean super low, |
|
| 37:16 | Because the cell doesn't wanna waste energy . So you just gonna have a |
|
| 37:20 | of these, a couple of of um of these uh molecules, these |
|
| 37:29 | wise proteins. OK. And so and so another thing here to point |
|
| 37:35 | is that the binding, right? we see in this scenario that back |
|
| 37:41 | here, right, lack repressor is , right? So these bindings, |
|
| 37:48 | , whether it's repressor operator or inducer repressor that these are not irreversible |
|
| 37:57 | right? They come off and on and on, right. There's a |
|
| 38:01 | called binding constants. Now this this the the affinity that the molecules have |
|
| 38:05 | each other, right? And so you were to take like AAA camera |
|
| 38:09 | take a snapshot, right, in the scenario, you see here where |
|
| 38:13 | repressor is bound, well, you , almost every time you go down |
|
| 38:17 | and take a picture, it looks this or it's bound. OK? |
|
| 38:22 | there will be times when it's not . OK? Not a lot, |
|
| 38:29 | enough where you can make, you , low level expression, right? |
|
| 38:34 | a couple of molecules work, And uh in the time frames when |
|
| 38:39 | like that unbound, that's when you sneak in a couple Mrnas worth of |
|
| 38:46 | . OK? And that's enough. all you need. OK? Because |
|
| 38:50 | will allow you to make the black OK? And so now the cell |
|
| 38:57 | see what's um just try to get and draw an eyeball. I don't |
|
| 39:04 | I can eyeball. There's an right? That's how we can see |
|
| 39:10 | lactose factor. If it didn't, could have a bazillion molecules of lactose |
|
| 39:14 | the cell. It wouldn't know it it doesn't have that black Y out |
|
| 39:17 | . OK. Think of black Y the, the lighthouse on the |
|
| 39:20 | OK? It's looking for lactose. . So um so if it is |
|
| 39:26 | , obviously it can come in and be processed by the LZ, |
|
| 39:35 | ? Part of it goes to AOL , right? Um It's kind of |
|
| 39:39 | on how much is out there, ? And so the, the um |
|
| 39:46 | of AOL lactose will then buying pressure you, you can go from what |
|
| 39:50 | be like in this state here, ? Repression. We had a little |
|
| 39:55 | of lack expression to form a couple those permeation, put them in the |
|
| 40:00 | . Then if it's see, oh have a boatload of lactose out |
|
| 40:04 | then very quickly, it will ramp like 1000 fold in terms of |
|
| 40:09 | OK. So that can increase very . OK? If lactose is indeed |
|
| 40:14 | , if it comes in the then lac Z does its thing, |
|
| 40:18 | ? Creating the inducer and then cleaning into the sugars and then off to |
|
| 40:25 | and respiration, et cetera, So that change can occur very quickly |
|
| 40:31 | wrap up very rapidly. OK? And within minutes, it can be |
|
| 40:39 | . Again, because the operator right, the whole pathway is |
|
| 40:46 | So all the genes involved in the where you can turn on and off |
|
| 40:49 | one time, right? So um lactose out there, come on |
|
| 40:54 | right? Um Now, so so just remember that there's another layer |
|
| 41:02 | this as we'll see in a So, um again, here is |
|
| 41:08 | Black Opera. So in the absence Black Coast, the the lac repressor |
|
| 41:15 | , actually, it binds and brings . So the la, the lac |
|
| 41:19 | itself has an operator with its regulatory and it actually binds to that and |
|
| 41:26 | the operator for the lack opera. you can see how both both are |
|
| 41:33 | and it comes together. So now have a polymerase, can't do |
|
| 41:38 | can't get around that. OK. there's no expression. OK? Um |
|
| 41:44 | if we have ll Latos present, binds, right? And you get |
|
| 41:49 | . So the active and inactive right? The active one blocks |
|
| 41:54 | the inactive one, you get right? And you only get the |
|
| 41:59 | form if the inducer is present the lactose right now, lol lactose only |
|
| 42:05 | if we have lactose, right? um OK. So that's, that's |
|
| 42:11 | layer of it. OK. So questions about that part of it? |
|
| 42:18 | the next layer is the glucose glucose . OK. Um Make sure you |
|
| 42:24 | questions out there. OK. So so here this kind of this question |
|
| 42:31 | meant to kind of address that part it. OK. So high level |
|
| 42:38 | of the lactose operon requires all of steps except what? So this is |
|
| 42:49 | glu glucose comes in. OK. does it do do? Mhm mm |
|
| 43:29 | . A couple of seconds here. OK. Let's count down to |
|
| 43:55 | OK. Um It is see So um obviously high level expression would |
|
| 44:08 | the absence, maybe it's not obvious it does the absence of glucose, |
|
| 44:14 | of lactose, absence of glucose. . Uh A repressor bound with AOL |
|
| 44:19 | means we are inactivating the repressor. you, you want that um we |
|
| 44:26 | mentioned we need D uh And so , you need e that's that |
|
| 44:33 | that complex uh like A MP. the CRP, the protein that binds |
|
| 44:41 | it to make it complex. You that. That's gonna act as an |
|
| 44:44 | . OK? Um But this, is controlled by this. OK? |
|
| 44:54 | The levels of cyclic A MP, , are controlled by. And what |
|
| 45:02 | that is glucose, glucose levels control um cyclic A MP levels. |
|
| 45:08 | Uh So we're gonna see how how that layer fits here. |
|
| 45:13 | Um Because what you need is you high levels like A P to get |
|
| 45:19 | level expression. OK? Um All . So here um so again, |
|
| 45:28 | we're forming is an activator that's gonna us get even more lactose expression. |
|
| 45:35 | , glucose, uh I'm sorry, alone isn't enough, right? So |
|
| 45:38 | have to manipulate the cyclic A MP . And what does that is the |
|
| 45:45 | of glucose? OK. So um there's uh optimal levels of cyclic A |
|
| 45:53 | , right, it will bind to cyclic A MP receptor. So they |
|
| 45:57 | a complex, right? And they together at the uh promoter. |
|
| 46:03 | And so assuming that you've got, know, the all lactose present in |
|
| 46:08 | binding to repressor to get that off there. OK? Then to get |
|
| 46:13 | , that's and so that's not enough just getting this right this to come |
|
| 46:21 | right into that form because we have , which made all lactose to bind |
|
| 46:26 | if you get it off. That's not enough. You don't get |
|
| 46:29 | lot of expression. So you have have activators bound to the promoter to |
|
| 46:36 | get the ply binding to it, get expression. OK. So |
|
| 46:41 | what controls is glucose? OK. and again, like I mentioned |
|
| 46:46 | glucose is uh a more streamlined carbon if you will, right? It |
|
| 46:54 | it can come into the cell. remember as it comes into the |
|
| 46:57 | it gets um the the the way transported, it gets modified, |
|
| 47:02 | Phosphate to glucose, six phosphate and right into glycolysis, right? Um |
|
| 47:09 | sugars typically have one or more steps get it processed, but it can |
|
| 47:15 | into glyco. And so of that's something that takes time and if |
|
| 47:20 | is present, it will override it it will be used first. |
|
| 47:24 | So, so how glucose affects cyclic is in terms of levels. So |
|
| 47:29 | glucose, low psychic A MP OK. Low glucose, high psychic |
|
| 47:34 | MP. OK. I think it's to um to somewhat to the levels |
|
| 47:41 | some kind of uh an indicator in cell is uh a ATP ad P |
|
| 47:50 | . OK? And I think this also to the cyclic A MP because |
|
| 47:54 | need, you need these components to a MP. And so um this |
|
| 48:00 | kind of an energy uh indicator in cell. Typically you want ratios of |
|
| 48:05 | 1.5 and you don't need to know , but uh a 1.5 ratio is |
|
| 48:11 | of a healthy cell. It's you have like a little bit of surplus |
|
| 48:14 | A TP over AD P. And if you find that, OK. |
|
| 48:18 | , there's no glucose, maybe that goes down, right? And uh |
|
| 48:24 | can affect like A P levels. that if there's a little sugar out |
|
| 48:28 | , it will readily be used. ? So it has something to kind |
|
| 48:32 | , that's kind of, I think they're tie it together kind of and |
|
| 48:36 | glucose can influence the levels here. . So uh so the bottom line |
|
| 48:41 | that's why you have to have glucose , right? Or low levels of |
|
| 48:46 | . OK? Because then you get high levels of ST like E |
|
| 48:50 | So you get more of these little thingies, right? And so now |
|
| 48:54 | get lots of binding, these are that can then buy into this and |
|
| 49:01 | plop onto the promoter. I love . OK? So um lactose present |
|
| 49:09 | absent um gives you high level OK? And so the um mechanism |
|
| 49:20 | we call this metabolite repression, So, catabolite are basically um molecules |
|
| 49:29 | for energy, right? So the like metabolism. So it's a, |
|
| 49:34 | a intermediate inca tabs and some kind catabolite pathway. So which lactose |
|
| 49:39 | it can be broken down, And so uh glucose exerts depression over |
|
| 49:47 | things like lactose and sucrose and nanos they happen to be around glucose is |
|
| 49:54 | one, right. Use it first then then the other things OK? |
|
| 50:00 | that's what gives you what they call growth. Basically think of it as |
|
| 50:05 | looks like a, a fed uh a a fed batch growth |
|
| 50:10 | You have one hump and then another . OK? As we'll see, |
|
| 50:14 | ? So here we go. So you have lactose, glucose and lactose |
|
| 50:20 | . OK? You use glucose OK? And then once it's |
|
| 50:28 | then do you, do you switch lactose? That's what that kind of |
|
| 50:33 | rose curve if you will. Uh using one source and the next |
|
| 50:38 | . OK. So um so if you, we're gonna, we're |
|
| 50:44 | put cyclic A and P levels, ? So with A and P |
|
| 50:52 | right? And getting higher. And I think API OK. And so |
|
| 51:00 | glucose is used up, you those levels begin to rise and once |
|
| 51:04 | is gone, then you get and is present, of course, throughout |
|
| 51:08 | whole time, then it switches over that one. OK. And so |
|
| 51:13 | the molecular level, what's going on ? Is this? OK? We |
|
| 51:18 | glucose uh as I said, it in and gets phosphorated, right? |
|
| 51:22 | so of course, the protein that it in contains the phosphate group. |
|
| 51:27 | . And so as, as the is taken off of these subunits and |
|
| 51:35 | to glucose, right? It's now phosphorated. OK. And in particular |
|
| 51:42 | this two a unit that is OK. So it loses the |
|
| 51:48 | gives it the glucose and that enables to interact with lactose. OK? |
|
| 51:54 | permeates, excuse me, lactose OK. And so basically shuts it |
|
| 51:59 | . It's like a plug. Glucose come into the cell now. |
|
| 52:04 | Because of this, this component that's un phosphorated, pardon the glucose |
|
| 52:10 | mechanism. OK? And so when is absent, well, then you |
|
| 52:14 | have that because it's phosphorated. And lactose is free to OK. |
|
| 52:21 | that's at the molecular level. That's going on. OK. So um |
|
| 52:28 | uh so let's look at um let's at I'm trying to see what's here |
|
| 52:36 | . OK. So here's kind of , the whole gist of it. |
|
| 52:39 | uh let's just look at this here or in addition to OK. And |
|
| 52:44 | again, this is what's available to on canvas. OK? I think |
|
| 52:49 | might find it helpful. Oops, it. Yeah. There we |
|
| 52:56 | All right. Um Shut up. right. So lack opera. Uh |
|
| 53:04 | Of course, it's a small segment the chromosome obviously. And so um |
|
| 53:10 | up of it. So we're gonna the genes we just talked about |
|
| 53:16 | right? Like Zy and A, A doesn't really do anything, |
|
| 53:22 | in terms of this function. um, and it's kind of fast |
|
| 53:27 | , hurt a little bit. All right. So here we got |
|
| 53:34 | out here, right? And your perm ase, OK. And |
|
| 53:42 | um, so that lactose present, course, we have very low levels |
|
| 53:51 | expression. OK? Says here, than 10 molecules, right? Um |
|
| 53:58 | . So here we go. Uh right, it's kind of slow. |
|
| 54:03 | . So there's, there's the lac repressor, right? That's gonna code |
|
| 54:06 | the repressor protein, right? Um see there transcript and then so |
|
| 54:16 | DNA RN A protein, right? lack of pressure in that state it |
|
| 54:23 | . So here's the operator sequence for Black Opera and the lac repressor, |
|
| 54:29 | ? So it kind of comes together um like so and so that's not |
|
| 54:38 | that Arnie polymerase can't even transcribe, ? Physically blind from it. |
|
| 54:45 | So there goes are, you can't anything. Goodbye. Um Now, |
|
| 54:55 | mentioned, you can get a fraction the time when it is exposed, |
|
| 55:02 | get a little bit of expression. ? Because remember we need that for |
|
| 55:06 | lack Y in particular, OK. so again, again, we're talking |
|
| 55:10 | a couple molecules only, right? high level. And so um there's |
|
| 55:17 | lactose, so disaccharide. So you the two units there and the processing |
|
| 55:24 | lactose like break that apart, but likes does that and um also forms |
|
| 55:37 | all lactose. OK. Can you this up here a little bit? |
|
| 55:42 | we go. There it is. so let's go here. All |
|
| 55:51 | So there's our or ply race. in that scenario, inducers bound, |
|
| 55:57 | get transcription expression. So glucose absent present right, hundredfold, higher |
|
| 56:09 | Uh So that's induction. OK. um activator. So here's our activator |
|
| 56:20 | absence, high psychic A MP levels uh and activator forms. OK. |
|
| 56:28 | , um then in next scenario, present lactose present, OK. |
|
| 56:39 | right? Bring a MP production, ? So we don't have the activator |
|
| 56:45 | um and blocking transporter lactose into the . OK? Um So, |
|
| 56:55 | and here's this OK. We see here as we just saw and so |
|
| 57:07 | . OK. Once glucose is utilized we use lactose. OK. Um |
|
| 57:15 | that's like a tablo repression effect. right. Um By looking at |
|
| 57:22 | are there now we're going to tryptophan . So any questions about glucose? |
|
| 57:30 | the lack opera? Excuse me. . So I think it helps look |
|
| 57:33 | the animation. Um certainly review the lecture. Uh But you're gonna |
|
| 57:39 | to be able to contrast, compare Black Opera Opera. OK. Um |
|
| 57:48 | you know, from the mechanic mechanistic , it still a regulatory protein binding |
|
| 57:53 | an operator, but it's just conditions gonna change. OK. Ok. |
|
| 58:43 | count that here. I read, it myself. I'm looking at this |
|
| 58:46 | in a while. The ID is . The Tryptophan corepressor is tryptophan itself |
|
| 58:52 | that's the only one that fits. . So, um, ah, |
|
| 59:02 | we go. Ok. So, , yeah, so, crypt Thehan |
|
| 59:07 | is a anabolic pathway. It's about crypto. Yeah. So, let's |
|
| 59:12 | at, um, let's look at question. It, it just goes |
|
| 59:17 | kind of why it works the way does. Why the tryptophan, let |
|
| 59:22 | back up. Why the tryptophan Operon the way it does. It's kind |
|
| 59:26 | based on this. All right. which Operon could e coli live without |
|
| 59:31 | you had a mutant, the chances that mutant living are greater if you |
|
| 59:41 | um if you have this one rather not having it, it lacks this |
|
| 59:46 | and it probably is not gonna OK. 543. Ask yourself the |
|
| 60:21 | question. Which opera can you? not opera? Which, which metabolic |
|
| 60:27 | can you not live without? Which ? Which one do you have to |
|
| 60:35 | ? Does everybody in the world eat ? No. Does everybody in the |
|
| 60:40 | need to make crypto fan? Every protein in your body has to |
|
| 60:46 | at least one tryptophan in it. you're not making tryptophan, you ain't |
|
| 60:50 | those proteins. You did. So, absolutely, I can eat |
|
| 60:55 | bazillion things. It can eat tons different sugars, fats proteins. Whatever |
|
| 61:03 | is just one little grape on the . OK. So, absolutely, |
|
| 61:10 | can live without lactose o on. there are E CO S that, |
|
| 61:15 | don't even, there are mutants. can't use it and they live just |
|
| 61:18 | . Right. But they don't live trip defense. You gotta make |
|
| 61:22 | OK. So the trip OPERON um the structural genes uh are enzymes |
|
| 61:33 | synthesize tryptophan. OK. Using this compound called charis mate. Don't worry |
|
| 61:40 | that. OK. The thing to is that it's, it's not tryptophan |
|
| 61:46 | , right? We're not breaking tryptophan , we're making it OK? So |
|
| 61:50 | a kind of anabolic pathway. Um So repression, right? So |
|
| 61:57 | they, what they call the April , OK. This form here is |
|
| 62:02 | inactive form. OK? So the itself, so the tryptophan is uh |
|
| 62:08 | present little or no, the crypto , we have what's called de |
|
| 62:13 | That means we are un unpressed. go that way. So we are |
|
| 62:18 | expression, right? If there's no thehan present, then the cell is |
|
| 62:25 | using it as fast as it's being . OK? So which means it's |
|
| 62:31 | accumulated, right? Because remember we're this material, it's gotta be going |
|
| 62:37 | , right? So, um so it is accumulating, right, then |
|
| 62:45 | must mean the cell doesn't need, have a use for it, |
|
| 62:48 | Otherwise it would be going away as as being used. But if there's |
|
| 62:52 | use for it, it accumulates. . So in that scenario is when |
|
| 62:59 | binds to the A O repressor creating holo repressor, the whole repressor because |
|
| 63:07 | acts as a corepressor, right? corepressor plus a repressor holo receptor polo |
|
| 63:13 | . Excuse me. So that's the repressor form. OK. So |
|
| 63:18 | if crypto fan is present, But so remember, you know, |
|
| 63:23 | all generating from here, right? presumably the cell needs it, |
|
| 63:31 | For protein synthesis primarily, right? if the demand is not there, |
|
| 63:40 | it accumulates. OK. Um I it's like a uh guy gal loading |
|
| 63:50 | her um Amazon prime truck with OK. So you're throwing them in |
|
| 63:58 | truck, right? So as fast they're coming off the conveyor belt, |
|
| 64:02 | throwing them in the truck. Nothing is accumulating. OK? Doesn't |
|
| 64:06 | to accumulate until the truck is right? Then where's it going has |
|
| 64:11 | ? As photo can't put in Then you have boxes piling up, |
|
| 64:14 | ? So now we can, the are crypto fan. Now it's available |
|
| 64:19 | bind to repressor. OK. so the question is, right? |
|
| 64:27 | Whether you're uh in the, so active hoop pressure binds to the operator |
|
| 64:35 | expression. So again, it's, know, like LAC Operon, |
|
| 64:40 | It's about the, the active repressor is what blocks expression. OK? |
|
| 64:46 | the conditions that cause it here are from what had happened in the LA |
|
| 64:51 | . But the active repressor role is same block expression. OK. So |
|
| 64:56 | question is, when would it be ? When would tryptophan be present? |
|
| 65:02 | . So this question here is meant address that. OK. When would |
|
| 65:09 | fan begin to accumulate in a OK. So you got mid log |
|
| 65:16 | log with crypto fans being decol or of the above? OK. When |
|
| 65:27 | tryptophan begin to accumulate and eat the ? Mhm OK. Cutting down from |
|
| 66:10 | 21. OK. OK. So see who, who picked um c |
|
| 66:29 | picked c why did you pick C Yeah. Mhm. Right. So |
|
| 66:41 | late log, they would have, , they're becoming limited, so they're |
|
| 66:45 | limited for growth, right? And in mid log, they're growing like |
|
| 66:50 | , right? So in mid they're really not limited for anything. |
|
| 66:53 | when the cells are their fattest, ? Then they're dividing like like |
|
| 66:58 | And so um they're not really limited anything in that mid law. |
|
| 67:03 | And so naturally Tryptophan is gonna be off the assembly line who make protein |
|
| 67:08 | protein divide, divide divide, It's not until you get to the |
|
| 67:13 | late log is the, the Amazon truck is almost full, right? |
|
| 67:18 | put any more boxes in there. . So 50 fan accumulates and it's |
|
| 67:23 | happen in late log. OK? the Tryptophan being made, there's not |
|
| 67:29 | demand so very quickly, then it's shut that off. OK. So |
|
| 67:35 | not mid, mid log is, happy as a clam, right? |
|
| 67:38 | growing like nuts, right? Not for anything. OK? But it |
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| 67:43 | out of that until late log. it's gonna put the brakes on |
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| 67:47 | OK? Because still division is going , right? You'll have the same |
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| 67:51 | for proteins being made, ok? It's obviously not one trip. The |
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| 67:56 | is being kept the tab like that's if you never, if you never |
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| 68:01 | do that this, it's not it's being used. OK? So |
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| 68:07 | about uh so the accumulation is tied what's the need of the cell? |
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| 68:12 | I growing like crazy? I need of proteins. I need tryptophan because |
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| 68:18 | , like I said, I'm gonna that every protein in the cell has |
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| 68:21 | least one tryptophan, right? If not, if you're, if you |
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| 68:27 | are becoming limited, then you don't it. OK? Slow down. |
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| 68:34 | ? Because you're just wasting energy OK? Um Many questions about |
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| 68:40 | OK? Oh OK. Um So is part one. OK. So |
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| 68:54 | , look at the animations which is kind of confusing, look at the |
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| 68:58 | and it helps you can put the caption on it. OK? But |
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| 69:02 | all I got today folks. We'll up part two Thursday. OK? |
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| 69:08 | a good |
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