| 00:01 | Ok. Yeah. Yeah. testing. Testing, testing carry |
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| 00:18 | Hey folks. Um we are going finish up um unit three today and |
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| 00:32 | you look on canvas, uh the four stuff is all up. Everything |
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| 00:36 | need. Unit four is up So we'll start on that next week |
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| 00:42 | um uh that screen looks weird. uh let's see here. Um So |
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| 00:50 | we've got a so uni quiz opens . Uh Nope, not that |
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| 01:00 | lights, lights. Um There is uh smart work do on Monday um |
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| 01:13 | this week. Ok. Ok. , there we go. Ok. |
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| 01:24 | Let's see what else? So smart do on Monday, the schedulers |
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| 01:29 | So remember the exams uh next And um so as always make sure |
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| 01:35 | stick to that damn review sheet, ? Because we didn't cover any of |
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| 01:40 | in their entire entirety chapters, So make sure you stick to |
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| 01:46 | And uh so remember the quiz that's be uh you know, covering a |
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| 01:50 | more comprehensive. You have like a more time to finish that. It's |
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| 01:55 | 20 I think it's 20 questions. And uh so just remember to do |
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| 02:02 | uh by Monday. And uh I that's it. OK. So, |
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| 02:12 | let's see here. OK. All . Um So context here, |
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| 02:21 | So we are um are talking about gene regulation, right? So, |
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| 02:28 | the importance of that um that, know, obviously it's one thing to |
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| 02:34 | proteins, the whole DNA RN A , right? Transcription and translation, |
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| 02:40 | cetera. Uh But certainly, and, and that uses lots of |
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| 02:45 | , right? Because you're building basically building a, making a transcript |
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| 02:50 | putting together nucleotides, right? Um synthesizing a protein is putting together amino |
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| 02:57 | , these are all anabolic process processes energy, right? So you don't |
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| 03:03 | to be doing these functions just willy . Um because you're just gonna be |
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| 03:08 | energy, right? So, gene , especially in new carriers is a |
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| 03:14 | , big deal, right? Um we're more complicated, we have, |
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| 03:21 | know, think of, think of happens as you go from the zygote |
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| 03:27 | right before you pop out of the , right? All the changes that |
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| 03:31 | , you know, those are all all have to happen in the sequence |
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| 03:35 | to develop into a fully formed right? So, of course, |
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| 03:40 | gonna be T control. OK. as it is in any living |
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| 03:45 | OK? So it's a big And um and so obviously, if |
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| 03:51 | we go from DNA to protein, ? If that's where you're gonna control |
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| 03:56 | , right? You're gonna control control at different levels. Um |
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| 03:59 | and either to increase or decrease it shut it off completely. OK. |
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| 04:06 | uh so the, and so here's of the, the levels, |
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| 04:10 | And I posted the slide on It was, I just kind of |
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| 04:15 | little more, maybe a little more different way to look at it. |
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| 04:18 | But these terms we look at and look at things other than lack |
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| 04:24 | We started the trip OPERON. So look at other things that fit into |
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| 04:27 | of these other categories. So we the top uh DNA, the transcription |
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| 04:33 | the RN A ply. All So remember in transcriptional control, you |
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| 04:38 | formed the transcript yet, right? the question is, are you gonna |
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| 04:43 | that or are you not? That's what transcriptional control is. So |
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| 04:46 | affecting the RN A ply. Signal factors can also be affected |
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| 04:51 | And we'll see an example of, , of that today, although uh |
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| 04:56 | doesn't fall into actually the transcriptional but we don't also, we don't |
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| 05:01 | into all the examples your book gives . So there are some examples where |
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| 05:04 | does fit there. Um But basically dealing with the promoter operator when you're |
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| 05:10 | with uh transcriptional control. OK. Post transcription was kind of a more |
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| 05:15 | term that actually covers all three of . So if two junior regulation, |
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| 05:22 | have two gene regulation, guys are to each other. Oh yeah, |
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| 05:26 | working on this posttranscriptional mechanism of control specifically it's you know, related to |
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| 05:33 | or, or instability or posttranslational. just kind of a more of an |
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| 05:40 | term if you will uh these are more specific terms that fall under |
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| 05:44 | OK. And so we looked at lactose opera. OK. It was |
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| 05:50 | first example. So uh remember uh that um the control, OK. |
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| 05:59 | um one level right is the is repressor operator, right? Having |
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| 06:06 | active uh repressor in the absence of , it'll bind blocking expression uh in |
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| 06:14 | presence of lactose, you form allo , which is the inducer that binds |
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| 06:19 | repressor in activating it alleviating the the on transcription. So you get expression |
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| 06:26 | that scenario. But remember the effect glucose exerts on the whole thing, |
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| 06:32 | ? So glucose is present in addition lactose glucose overrules through affecting cyclic A |
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| 06:40 | levels. OK? Because that will OPERON also needs that activator complex which |
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| 06:47 | a combination of cyclic A MP and receptor protein for it. And so |
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| 06:52 | go to the promoter and increase And that's and that's is influenced by |
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| 06:57 | glu glucose presence, absence of OK? I also remember that glucose |
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| 07:03 | uh the presence of glucose blocks the of lactose, right? So it's |
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| 07:09 | it's a uh it has that's what call it. The tite repression, |
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| 07:14 | ? Glucose is blocking these, the of these other types of catabolite. |
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| 07:19 | what lactose is. OK. Um questions about that? So, like |
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| 07:25 | said, look at the animations, think that helps. OK. Um |
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| 07:31 | as we go into the Tripen O which we started at the end, |
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| 07:34 | time, you're gonna wanna make sure got, you know, this black |
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| 07:39 | straight because you're gonna have to be to compare the two. OK. |
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| 07:44 | um so we ended here, we at the kind of the basic uh |
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| 07:51 | and what you're seeing here um or you're about to see and what we |
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| 07:56 | about that at the end last time relation to the Tryptophan opera that control |
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| 08:02 | takes care of most of the um repression of the Opon, right? |
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| 08:14 | there's an additional like we had an layer with Glu uh the Black Opera |
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| 08:19 | the glucose effect. We have also , another layer to try thehan |
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| 08:24 | And that's that, that's that attenuation . OK. So that one can |
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| 08:28 | a little bit complicated. So we'll through it um bit by bit. |
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| 08:34 | first, so first and fore remember hip opera, lactose opera two |
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| 08:42 | different in terms of uh of their of metabolism, right? So, |
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| 08:48 | Operon is about metabolism that's bringing lactose break it down. All right, |
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| 08:53 | into glycolysis. So we can make , right? Tryptophan Operon is the |
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| 08:58 | . It's an OPERON set up to synthesize tryptophan. OK? So we're |
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| 09:03 | tryptophan, we're not eating it through opera. OK? Um So we |
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| 09:09 | the same, you know, remember operon structure, right? The regulatory |
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| 09:14 | . So we have a promoter, ? Regulatory protein and promoter operator |
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| 09:19 | right? And so they code for um the uh transcript obviously and then |
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| 09:29 | enzymes that um set the size OK. I'm starting with this uh |
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| 09:35 | material, five different enzymes. We tryptophan. OK. And so it's |
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| 09:41 | uh a repressor as well. And so tryptophan and the repressor work |
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| 09:48 | . OK. So tryptophan is kind self regulating. OK? We have |
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| 09:53 | inactive form where tryptophan is not bound tryptophan is the corepressor. OK? |
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| 09:59 | involved in its own regulation, So if we have little or no |
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| 10:05 | fan present, then it's gonna be inactive form and we get expression. |
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| 10:09 | remember crypto fan is gonna be use it to make proteins. So |
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| 10:16 | it sells in a high demand, protein, higher protein synthesis producing |
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| 10:23 | which it would be if it was quickly, right? Rapid growth, |
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| 10:27 | when cells divide rapidly, gotta make of proteins to keep that sustain that |
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| 10:32 | of growth. OK? And so is one of 20 amino acids guaranteed |
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| 10:38 | there's gonna be at least one tryptophan , in every protein. OK. |
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| 10:42 | it's essential to keep this being expressed you have a high demand for |
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| 10:46 | right? This stuff is going, away. So it during that period |
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| 10:53 | rapid growth, if you are able , if you measured the levels of |
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| 10:58 | crypto fan, it'd be very low it's being used as fast as it |
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| 11:03 | made. OK? Um But we know our growth curve will eventually flatten |
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| 11:11 | , right, become limited. And this tryptophan would not be being used |
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| 11:16 | fast as being made, right? it accumulates. So now it's free |
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| 11:22 | bind the repressor, right? And we activate the repressor now because you |
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| 11:28 | need, if it's crypt thehan is , it means it's not being |
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| 11:32 | So don't make it, you're wasting , right? So crypto family bind |
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| 11:36 | pressure, activate it and will block . OK? So this control, |
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| 11:44 | see that takes care of, I'm gonna put a number on it, |
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| 11:48 | it takes care of most, let's 99% of the control the chip opera |
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| 11:53 | is through this. OK? But . So before we go on uh |
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| 11:59 | questions about it, OK. So again, it's, it's, |
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| 12:04 | similar to LAC Operon, it's about and inactivating a repressor, right? |
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| 12:09 | the conditions are different, right? The the presence of lactose, |
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| 12:16 | which then goes to all of lactose binds to repressor um inactivating. |
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| 12:22 | Here, cry to fan the corepressor to the repressor activated, right? |
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| 12:29 | . But it's it and it goes really the the type of metabolism we're |
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| 12:34 | about. So crypto fan, that's critical pathway, right? You can |
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| 12:39 | coli can live without Black Opera. ? It couldn't even have enough. |
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| 12:50 | pretty sure E coli can find other . OK? Um But it can't |
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| 12:56 | without making proteins. OK. So of the logic here if you will |
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| 13:02 | that's kind of what the end product things, right? So that can |
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| 13:06 | kind of a gauge in the cell OK. Are we having rapid |
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| 13:11 | Do we need lots of this amino or do we not need that? |
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| 13:15 | so kind of like the control? that makes sense if it's a very |
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| 13:19 | pathway type process. OK. Um I, I think all the other |
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| 13:26 | meal acids are controlled the same OK. So um now the uh |
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| 13:35 | we should be present, as I , it would accumulate, there wasn't |
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| 13:38 | demand. So growth was stopping. was it, it didn't uh it |
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| 13:43 | need that level of protein synthesis. it would build up and then then |
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| 13:47 | itself off. OK. So So here is a comparison. |
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| 13:56 | So we have E Coli uh which the lac operon and the TRIPP |
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| 14:02 | right? Is grown in minimal minimum . I don't remember what that |
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| 14:08 | So we've added uh both lactose and to the medium, no glucose is |
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| 14:17 | . OK. So what can you with respect to the lack and Trip |
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| 14:22 | . Yeah. So uh black opera the opera expressed in black opera. |
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| 14:29 | or no, like upper on Hope that's the H VAC system but |
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| 14:41 | uh in varies from Mars. Um . So Black Op One is |
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| 14:46 | Yes. OK. Because, We got the conditions right. No |
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| 14:53 | . All right. And lactose is . OK. Um Trip Operon. |
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| 14:59 | or no. No. Because um being supplied to the fan, |
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| 15:08 | And it's, it's going to bind the repressor and then what's not bound |
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| 15:15 | repressor elite right there? No need make it. You're, you're, |
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| 15:19 | being bathed in tryptophan. Why make ? All right. Uh Oops jump |
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| 15:24 | gun. OK. Um OK. Operon, what's the state of the |
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| 15:29 | ? So it's inactive, right? lactose operon? Because uh lactose is |
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| 15:34 | forming L lactose binds the repressor and it, right? And in the |
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| 15:39 | upon it is of course active. ? Because if the fans present |
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| 15:45 | we're, we're handing it to we're dumping into the medium. So |
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| 15:49 | there and it's um it's uh binding the professor activating it and but then |
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| 15:58 | the rest of it for its own . OK? And so cyclic E |
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| 16:02 | levels, they have no, no A on like like a P levels |
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| 16:13 | be high or low should be high I remember no glucose is present, |
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| 16:20 | ? So it should be hot. get the complex forms and you get |
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| 16:24 | of transcription, et cetera. So um OK. So let's look |
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| 16:33 | this. All right. So we went through this, right? So |
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| 16:36 | I said, this kind of right, involving repressor, right, |
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| 16:43 | uh levels of tryptophan determine whether you expression or not, right? That |
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| 16:49 | care of the majority of the But you still can have a scenario |
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| 16:56 | even though binding, right, remember bindings here, whether it's really whatever |
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| 17:05 | uh nucleic acid or protein protein, always a binding constant, right? |
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| 17:10 | bindings usually are not irreversible, they reversible to a certain degree. It |
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| 17:18 | OK. The point is this this protein, active repressor protein when it's |
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| 17:24 | , it's not there 100% of the there is a small portion where it's |
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| 17:29 | , right? And so when that happen, even in the repressed |
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| 17:36 | right, as shown here, um uh let me erase this. So |
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| 17:43 | as in the repressed straight, you here, OK? Well, in |
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| 17:47 | state, OK, you can get little bit of expression when that thing |
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| 17:53 | off. Now put a clamp on . All right, to really say |
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| 17:59 | , even when it's that 0.01% of time when it's not bound and it |
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| 18:05 | off, I still wanna be able control it. OK? That's where |
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| 18:10 | leader sequence comes in, right? the box, so every time a |
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| 18:14 | is made for this opera. That part, right? That boxed in |
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| 18:20 | , that's that leader sequence. There's a part of the transcript. |
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| 18:24 | And so it also serves as as another control, secondary control. |
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| 18:30 | ? And that's what we're gonna, what the attenuation mechanism is all |
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| 18:33 | Right. So we're gonna get into here in right now. And so |
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| 18:37 | it is, it's, um, a transcriptional control because we are affecting |
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| 18:45 | or not RN A Pyra can transcribe trip opera. OK? It's just |
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| 18:53 | controlling it is a ribosome. The is actually controlling it, right? |
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| 18:58 | it looks, it's gonna look kind weird, but ultimately, it is |
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| 19:02 | transcriptional control. It's just a ribosome kind of controlling it. OK? |
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| 19:07 | Brook calls it a sensor. So, OK. So number |
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| 19:12 | remember that when a transcript is the leader sequence is always a part |
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| 19:17 | it right up front. OK. is that the leader sequence uh does |
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| 19:24 | make any kind of usable protein, ? It's simply only there as a |
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| 19:32 | process. OK. Um The other is to note location, right? |
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| 19:40 | trip L is a leader sequence and here, this junction, that's where |
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| 19:45 | structural genes begin, actually goes It's not ABC de, it's E |
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| 19:53 | B A in that order. And so this is really the critical |
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| 19:58 | . So if Arne Pli is sitting , it started here, right? |
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| 20:03 | it goes the point of no return right there. Right? It's right |
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| 20:11 | , where it gets to the structural . So this, this um mechanism |
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| 20:17 | all about, OK? Is that is gonna be able to go into |
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| 20:22 | structural genes? Right? Will it there or will it stop? |
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| 20:26 | And that's the, that's really the of the whole thing, right? |
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| 20:29 | either allowing it to keep going or knock it off. That is what |
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| 20:35 | is. OK? So now it's . So then the question is, |
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| 20:40 | , what's, what's causing that whether not gets knocked off or keeps |
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| 20:43 | Right. So, so kind of backwards, then it's um about the |
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| 20:52 | from this leader sequence. OK. And so the transcript that's made um |
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| 21:02 | has secondary structures from RNAs molecules have structure or moves and, and |
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| 21:08 | OK. It's all a UGC OK. And so this RN a |
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| 21:14 | sequence can form these two loops actually . Um They can also form a |
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| 21:22 | , it's re loop. OK. so 1234 are the regions where there's |
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| 21:28 | where they can complement your base. . So the 23 can also form |
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| 21:33 | the 23 is actually the and uh writing. Hold on. Yeah. |
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| 21:45 | . OK. Um So we call the anti attend you later. That's |
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| 21:56 | , that's the 2323 loop is the attenuator. The attenuator loop is |
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| 22:03 | So, remember attenuate means to limit to stop. OK. So the |
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| 22:09 | thing to note here is this junction , here's our junction here. |
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| 22:18 | Between where the structural genes start. note distance here, a tener loop |
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| 22:26 | distance here. OK. What's closer itinerary loop, closer proximity to that |
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| 22:36 | , the anti itinerary loop farther OK. There again is how this |
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| 22:42 | . This loop here physically locks off polymerase can't go beyond structural when it |
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| 22:51 | , that structural gene starts like right? The anti tenure loop is |
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| 22:57 | away. So it can't physically interact polymerase. It keeps built. |
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| 23:03 | So that's those two loops, which forms? It is what controls whether |
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| 23:10 | ray keeps going or it gets knocked . OK. So go back another |
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| 23:15 | or how does one loop form versus other? OK. Well, remember |
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| 23:20 | a transcript and ribosomes bind the right? They bind and start |
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| 23:27 | OK. So um so it's about the ribosome starts, uh stops or |
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| 23:35 | , right? Determines which loop forms tenuity or attenuated, right? |
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| 23:44 | because the secondary structure loops forming, are influenced by a big fat ribosome |
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| 23:51 | on the transcript and either allowing some to form and not others, |
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| 23:58 | So it's about where is the ribosome ? Stopping at? OK. Determines |
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| 24:03 | loop forms. OK. OK. what, what determines where the ribosome |
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| 24:08 | ? Well, these things OK. . So remember in the ribosome, |
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| 24:17 | , it, it parks itself on transcript and you're gonna have coons, |
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| 24:21 | ? So Trnas recognize coons to anti , right? And so you have |
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| 24:29 | types where you can have one that's that contains a tryptophan and one that |
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| 24:35 | it. Ok. So they both the same, right? Anticodon, |
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| 24:42 | ? AC C AC C. So recognize those Tripp codons, right? |
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| 24:48 | one is carrying an amino acid, tryptophan, the other one is |
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| 24:53 | So then what under what scenario would have uncharged? Trn A? If |
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| 25:01 | C is like starving for tryptophan? ? The so doesn't have any tryptophan |
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| 25:06 | not, not a lot of then it can't make a charge to |
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| 25:09 | A. Ok. And so that's of how tryptophan levels influence the levels |
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| 25:19 | charged trn A. Ok. Higher , so low levels, mostly uncharged |
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| 25:26 | pr news. OK. Lots of around lots of charged trn A. |
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| 25:33 | . So what happens is when an trn A plops itself down uh uh |
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| 25:38 | on the codon? Remember? So when, when you have Trnas, |
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| 25:44 | ? You link up the amino right? The chain growth that |
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| 25:50 | So if you have a uh trn sitting there that's not charged, there's |
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| 25:55 | to, to hook, hook onto , to hook on to the growing |
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| 25:59 | , right? So it stops, sits there, right? And so |
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| 26:04 | what determines whether you form which loop . If you have lots of, |
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| 26:08 | of uh tryptophan, lots of charged and here it comes, here comes |
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| 26:13 | trip code on bam, bam. come in, you connect and you |
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| 26:18 | , right. So there's no Right. Keeps going. So that's |
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| 26:22 | you have, I'm kind of taking from the end to the beginning. |
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| 26:26 | why you have, um, that's it affects the location where these coons |
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| 26:34 | at. Right. So here are two adjacent trip coons, right? |
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| 26:39 | here's a stop Codon, right? what we call the usual, the |
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| 26:44 | endpoint, right? Of a transcript to stop code, right? And |
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| 26:49 | it's got that, of course, the what kind of influences whatever it |
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| 26:53 | stop before then are those two trip ? OK. So if a ribosome |
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| 27:00 | there and there's not a lot of trip Trnas, then it's gonna |
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| 27:05 | OK. And then that means the loop forms, I'm sorry, |
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| 27:12 | So let, let's let's look let's go through this again. |
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| 27:16 | But um so it's, again, about the positioning of the RS which |
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| 27:22 | , what influences where the ribosome stalls stops is the levels of trn a |
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| 27:27 | tryptophan because that influences the levels of tras to charge tr A Yeah, |
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| 27:38 | are you with me, you kind of convoluted but, and I |
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| 27:41 | of it, I'm kind of taking from the end the other way, |
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| 27:46 | think, I think makes sense. . Um So it's all about positioning |
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| 27:51 | and stopping this prelimerase before it gets that new structural genes, right? |
|
| 27:58 | let's look at um here. So high crypto levels, right? So |
|
| 28:03 | this, if you like in the , right, we had e coli |
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| 28:07 | , we've added tryptophan to it. . So this would be what, |
|
| 28:10 | happening, what's happening here. So have lots of these, right, |
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| 28:16 | of these uh in that scenario. so as the ribosome binds and begins |
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| 28:22 | translate, it's gonna blow right through trip code out. There's no stalling |
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| 28:30 | right through and it goes to the stop point, which is the |
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| 28:34 | stop code on. OK. And can see how it's overlapping right here |
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| 28:41 | area one, here's area two, ? So it's got that covered |
|
| 28:45 | right? And so three and four form quite easily. OK? And |
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| 28:50 | note the distance right here to OK? And so, and |
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| 28:56 | here's, here's that junction, We gotta stop it before it gets |
|
| 29:01 | the purple structural genes. So, that's how it it, so it |
|
| 29:05 | interacts with it, right? And knocks it off. OK. So |
|
| 29:11 | prevent transcription, which is what you , right? You got, you |
|
| 29:14 | lots of crypt thehan, you don't to make it. But again, |
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| 29:19 | first mechanism we looked at right, repressor, corepressor thing that's gonna take |
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| 29:23 | of most of this control, but do have this as well as the |
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| 29:27 | like let's put a stop to OK? Um Now in the Loreen |
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| 29:36 | , so it's starving for these amino . Then you're gonna have mostly these |
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| 29:42 | ? Forms of tr A OK? amino acid attached to them. |
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| 29:46 | So in that scenario, then it's stall at those adjacent trip codons right |
|
| 29:52 | because here's the regular stop code on . It, well, before |
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| 29:58 | OK. So you see that now , the two, it's, it's |
|
| 30:03 | really the, the, the front of this transcript here, right? |
|
| 30:07 | the two, it's free, you buy. So 23 forms. So |
|
| 30:13 | , if you had and, and , and which loop forms is really |
|
| 30:17 | thermodynamics. OK? If you were take this, this transcript, that |
|
| 30:24 | sequence and plop it into a, buffer solution, what you mostly see |
|
| 30:29 | 23 loops. It's, it's, thermo dynamically favored likely because there's |
|
| 30:35 | there's more A T eight, I'm . A Uau only two hydrogen bonds |
|
| 30:40 | GC three, right? So it less energy to form, form the |
|
| 30:44 | loop, right? So if it's free in solution without a L, |
|
| 30:48 | 23 loop form, but what's preventing is the ribosome positioning. OK. |
|
| 30:54 | um the um so again, because , it stalled here, the two |
|
| 31:01 | is free to do its bank. the 23 forms and just looking |
|
| 31:06 | all right distance, right, much away. Can't interfere with it, |
|
| 31:11 | ? So it keeps, it keeps , keeps transcribed, which is what |
|
| 31:15 | wanted to do. Right. Lowry fan, you want to keep |
|
| 31:18 | OK, to get transcription. uh, let's see before you answer |
|
| 31:25 | question. Well, let's do this quick. All right. Um And |
|
| 31:30 | , you have access to this and the beginning part of this is what |
|
| 31:36 | seen already right? There is the , the whole thing. Um And |
|
| 31:41 | we have an active repressor binding and get transcription and that ha happens when |
|
| 31:47 | fan binds to the repressor, Corepressor repressor complex. OK. Um |
|
| 31:55 | this up a little bit. So goes away, uh repressor is now |
|
| 32:01 | and you get uh expression, expression right there. And so it |
|
| 32:09 | kind of just go up here uh , there, there we go Indian |
|
| 32:16 | . Yeah. So let's look at attenuation mechanism up here. OK. |
|
| 32:26 | back, a bit back, a back of it. Come on. |
|
| 32:37 | . So it do its thing. . Uh So you see the structural |
|
| 32:43 | don't start until a ways down to right. OK. So there's a |
|
| 32:48 | sequence and come on. There we . So we get transcription. So |
|
| 32:56 | that's always gonna be, you're always transcribe that. OK? And there's |
|
| 33:00 | leader, you get your four right? 23 anti attenuator, uh |
|
| 33:11 | and like that. So one and conform, you know, again, |
|
| 33:15 | that really doesn't um in uh because ribosome covering it. So, um |
|
| 33:26 | in the, what are they what are they gonna do first? |
|
| 33:31 | , in the presence of lots of , then you would get the, |
|
| 33:40 | thing is so slow. Let's keep here. OK? Because this guy |
|
| 33:45 | talking over this time. All 40 me for me, peptide Dr |
|
| 33:52 | , right? And so in high levels, you are going to have |
|
| 33:58 | of charges. Trip Trnas. All . And come on ribosome. There |
|
| 34:05 | go. So here comes the ribosome , boom. It's gonna go right |
|
| 34:10 | onto this regular stop code on in and that a tar loop forms and |
|
| 34:18 | is very close to the prelimerase and it off. Then in the next |
|
| 34:27 | , low trip the fan it of will stop. OK. Right |
|
| 34:36 | So the tooth really forms and it's away from the lime race. It |
|
| 34:40 | continue going Jack. Um All So let's uh look at this |
|
| 34:52 | OK. So the attenuation mechanism that block expression of the chip opera would |
|
| 35:02 | all of these except so what is exception that so blocking expression and don't |
|
| 35:22 | e there is an exception. So gonna be ABC or D OK. |
|
| 35:51 | . OK. Cutting down from OK. 210. And the answer |
|
| 36:12 | you, you picked, wait, picked my favorite question? Who picked |
|
| 36:19 | B? Who picked B well, know, you know the answer. |
|
| 36:23 | , who, who picked b, picked b, anybody else? Anybody |
|
| 36:28 | the back row? Yes. Why it? B, yeah, middle |
|
| 36:35 | without looking at your computer. that, mm. Right. |
|
| 36:53 | Yeah. So you're gonna have of course, because A, is |
|
| 36:56 | , is a function all the You're always going to get the MRN |
|
| 37:00 | of the leader sequence. Whether you the fan that's going to happen. |
|
| 37:06 | Again, repressed state, the levels leader transcript you form will not be |
|
| 37:14 | lot because it's mostly bound. But can, there's times when a little |
|
| 37:18 | of time that comes off, you a little bit OK? But a |
|
| 37:21 | happen at a, at some OK? Uh In every scenario, |
|
| 37:27 | formation of a tener loop, of , itinerary loop is what form, |
|
| 37:30 | the whole thing about blocking expression, form C OK? And of |
|
| 37:35 | uh C happens because of the, get lots of crypto fan, you |
|
| 37:39 | lots of charge trn a crypt thehan um you then will stall at the |
|
| 37:46 | code on. OK? And that's will form cause the 34 to, |
|
| 37:51 | form this one, right? I mean that is the exception, |
|
| 37:55 | ? But remember it's, it's, gonna start the, if we're shutting |
|
| 37:59 | down completely with the leader sequence, gonna want um that's gonna happen in |
|
| 38:06 | Hypopen which leads to lots of trip which means you're gonna blow through the |
|
| 38:12 | codons, they're gonna stop at the coon still the stock code on. |
|
| 38:16 | . So, uh to make, make b correct in this context, |
|
| 38:22 | would say the RS are installed at stocks that would make it correct. |
|
| 38:27 | it's not as written, it's not in this scenario, right? Um |
|
| 38:33 | questions about that. So, you , I it's a, with this |
|
| 38:39 | , Uh there's different ways you can about it. I find it helpful |
|
| 38:43 | go from the end back the other . But um look at the |
|
| 38:48 | OK. So it's all about in a nutshell. It's all about |
|
| 38:53 | allowing that ribosome to keep going and express and transcribe structural genes or |
|
| 38:59 | . So either knock it off or it keep going, right? So |
|
| 39:13 | of, I don't know, uh of it as a story, think |
|
| 39:17 | it as a story, right? um that might be a way to |
|
| 39:21 | you remember it. OK. Um you look at the animation, I |
|
| 39:26 | it helps. OK? And you turn on the closed caption, you |
|
| 39:30 | the whole nine yards or just rewatched lecture video. OK. So |
|
| 39:38 | 121, no, because the rival should be sitting on top of one |
|
| 39:47 | . Yeah, because one, that , I don't think foreign because r |
|
| 39:51 | basically sitting on top of it for most part. And So it's not |
|
| 39:56 | , you gonna be 23 or 34 most part. Yeah. You, |
|
| 39:59 | one of those two? Oh, forgot I had another question. So |
|
| 40:02 | quick here. So um OK. low versus high trip levels inside the |
|
| 40:09 | . OK. Uh low in intercellular . So, synthesizing tryptophan that will |
|
| 40:16 | under lower high. Yes. OK. Uh transcribe operon uh lower |
|
| 40:28 | . High levels. Yes. OK. Um The trip repressor corepressor |
|
| 40:37 | form low levels. No, high . Yes. Right. Um Charge |
|
| 40:45 | trn A is plentiful. Uh low area levels. No, I, |
|
| 40:52 | course, it's present you can make . We do sequence calls at trip |
|
| 40:58 | stop codes. OK. Um Which leader sequence forms low interest size or |
|
| 41:07 | interest size. So the low level gonna be the 23, right? |
|
| 41:12 | 23, high level 34. And obviously these lines would be present. |
|
| 41:19 | I mean, you know, it seems like I'm spending a lot |
|
| 41:22 | time on this. There's maybe like , a couple of questions on the |
|
| 41:26 | that will relate to this. um anyway, do you have any |
|
| 41:31 | ? Right. Right. OK. right. So let's look at something |
|
| 41:39 | . Well, I'm still going on this. That's uh let's uh just |
|
| 41:43 | going here unless anybody has any OK. So let's look at these |
|
| 41:47 | mechanisms. Let's get out of lack trip OPERON for God's sakes. |
|
| 41:53 | So uh stringent response phase variation, factor control, regulatory RN A. |
|
| 41:59 | in your book, goes into a more examples of different types. I |
|
| 42:03 | picked like a few just to give a little sampling. OK. So |
|
| 42:07 | stringent response, OK. So this also a I call a transcriptional control |
|
| 42:16 | you are affecting the transcription of in case, ribosome RN A genes, |
|
| 42:24 | ? So this happens when typically when cell is starving, OK? And |
|
| 42:29 | you're starving, as we just saw tropine uh mechanism, uh the levels |
|
| 42:35 | , of charged Trnas uh are right? So if you're starving, |
|
| 42:41 | it's starving, bacteria is starving, that can happen where you don't have |
|
| 42:44 | charged Trnas for their respective um amino . And so that will cause it |
|
| 42:50 | stall as we saw how that happened the attenuation makers. OK. So |
|
| 42:55 | that kind of scenario, OK, um which can happen, of |
|
| 43:01 | when you know, you're, the are growing, right? And you |
|
| 43:04 | that stationary phase, right? You become limited, right? For |
|
| 43:09 | And that's of course, as a point for the cell as well, |
|
| 43:14 | ? So then it becomes AAA mode OK, let's conserve energy. |
|
| 43:19 | you know, we gotta, we keep, we're not growing like |
|
| 43:22 | So we don't need to keep synthesizing like we did before. So let's |
|
| 43:25 | it down, right? Kind of into survival mode and the way to |
|
| 43:29 | that is to, is to initiate activity that's associated with the ribosome. |
|
| 43:35 | this what's called El Rel um right. So it's a pro that |
|
| 43:40 | of hangs, hangs out with the . And when this scenario occurs where |
|
| 43:45 | kind of starvation and these, and um uncharged pr Nas begin to plop |
|
| 43:51 | in and arrives on stones. That's of what induces this whole process. |
|
| 43:55 | so this enzyme basically takes phosphate from TP and hooks it on the GTP |
|
| 44:02 | make this guanosine tetraphosphate. It's like little si signaling molecule. OK. |
|
| 44:08 | uh what it does it interacts with or Plimer specifically the beta subunit. |
|
| 44:15 | ply has beta and alpha units that to create the transcription and that will |
|
| 44:21 | alter their ability to really for the the um promoters that, that are |
|
| 44:28 | for transcription of ribosome RN A, . So these, these are the |
|
| 44:32 | of gene that the end product is a protein but is the RN A |
|
| 44:38 | . So, of course, the are made of RN A molecules and |
|
| 44:41 | , right? So if you're not the ribosome RNAs or expressing them, |
|
| 44:45 | not gonna make protein uh ribosomes, ? Which is what you want to |
|
| 44:49 | . If you're not, if you're really wanting to express the synthesized |
|
| 44:54 | then get rid of ribosomes. That's of what's happening here again, all |
|
| 44:59 | the effort to, to to uh really a stress situation, like |
|
| 45:04 | got to conserve energy, you you keep synthesizing proteins at the same |
|
| 45:09 | . So let's, let's inhibit um A uh primos RN A expression. |
|
| 45:16 | ? Because again, it's an anabolic for making primos RNAs, you're the |
|
| 45:21 | nucleotide that's using energy. So let's do that. OK? Um As |
|
| 45:26 | as let's by doing that, then default, you're lowering proteins as |
|
| 45:30 | which is energy consuming. OK. it's really about survival here. |
|
| 45:35 | Um So, because we are manipulating polymerase and affecting transcription, right? |
|
| 45:42 | call it a uh transcriptional control OK? For affecting the ability to |
|
| 45:50 | to transcribe. OK. So uh one here is way different. It |
|
| 45:57 | uh DNA. So now we're basically at the top level of control. |
|
| 46:02 | affecting your DNA. OK. So is something we see in a lot |
|
| 46:08 | pathogens. We'll bring, we'll mention again in chapter 26 or chapter 25 |
|
| 46:16 | in the context of microbial pathogenesis, ? This is a way for cells |
|
| 46:22 | can do this to hide from your system. That's what um immune avoidance |
|
| 46:28 | to. OK. Is hiding from immune system. OK. And so |
|
| 46:33 | this occurs with virulent genes in these that have multiple forms. OK. |
|
| 46:43 | It could be like uh with a , you have, you can have |
|
| 46:48 | constituents of a capsule and express different at different times with the flagellum. |
|
| 46:53 | remember it's that flagellum protein, You hook together to make a flagellum |
|
| 46:59 | you can have different variations of that amino ao sequences for those flagellum, |
|
| 47:05 | ? And you know, it could capsule could be fibri, it could |
|
| 47:09 | a uh a flagellum. Uh there's antigens that can change. OK. |
|
| 47:15 | so uh so, so why do ? Well? OK. So the |
|
| 47:19 | here is salmonella is a foodborne Um So it, it's mo through |
|
| 47:26 | . So remember in terms of the system, the things on the periphery |
|
| 47:31 | the pathogen, it's virus, protozoan and what have you the stuff |
|
| 47:36 | the outside surface proteins? A A S layer, gram negative uh a |
|
| 47:44 | of flagellum. These are all things the periphery. That's what your immune |
|
| 47:48 | cells look for because you can, can recognize them as an OK. |
|
| 47:54 | then we'll learn about this party next , but an antigen antibody interaction brings |
|
| 48:00 | lots of different effects. OK. um so the pathogens have evolved ways |
|
| 48:10 | get around that. OK. And of the major ways is to temporarily |
|
| 48:16 | their antigen profile if you will, ? Because doing so makes them |
|
| 48:22 | OK. Your immune system cells don't it. So it's all, it's |
|
| 48:26 | based on these things aren't permanent, all about time, right? You |
|
| 48:31 | , knowing how fast bacteria grow. they can buy some time, then |
|
| 48:35 | can rapidly grow and, and you , obviously cause serious infection. So |
|
| 48:42 | you, your body does the same in terms of buying time, |
|
| 48:45 | You get a fever that, that the growth of pathogens and so it |
|
| 48:50 | you time for your immune system to up, right? So it works |
|
| 48:54 | ways. Ok. So um so this works is like this, |
|
| 48:59 | So we have two forms of these proteins, two H one H |
|
| 49:04 | OK. So a A cells flagellum , the salmonella, its flagellum is |
|
| 49:12 | be made up of one of these . You do the H one form |
|
| 49:15 | the H two. OK. So this scenario, it's using the age |
|
| 49:21 | , OK? And so the two that control it B and C |
|
| 49:27 | Um So promoter, so keep your on that, right? The promoter |
|
| 49:33 | the whole thing. OK. Um in this scenario, we're expressing the |
|
| 49:40 | two flagellum because we're expressing this B along with part of the transcript and |
|
| 49:46 | is this repressor protein. OK. it is what binds and blocks expression |
|
| 49:53 | that second um flagellum protein, So this particular um salmonella is only |
|
| 50:02 | the H two flagella, right? the other one. OK. Now |
|
| 50:07 | happens? And this is kind of spontaneous event. I'm not sure what |
|
| 50:12 | rate is. Something like maybe once 10 of the 4, 10 of |
|
| 50:16 | six uh frequency, it will OK. So the recombining section is |
|
| 50:22 | green, right? And it contains promoter, right? That's the |
|
| 50:30 | it contains the promoter as part of section of DNA that we combine. |
|
| 50:36 | . So what happens is um the these hin genes synthesize a um |
|
| 50:46 | and then synthesize a protein that's that combine. So we call it Recombinate |
|
| 50:50 | scissors to cut it, cut it invert it. So sequence basically here |
|
| 50:55 | being rearranged, right? It gets out and then inverted. So you |
|
| 51:00 | see right here how it's flicked. so the promoter is right there. |
|
| 51:07 | so it is now um no longer in front of here because this is |
|
| 51:15 | codes for the age two, And for the repressor, OK, |
|
| 51:24 | two genes, OK. So that no longer expressed because the promoter which |
|
| 51:29 | in front of it has been went with the segment that we combined. |
|
| 51:34 | so now it's sitting over here facing that direction. OK. So you're |
|
| 51:39 | gonna express those two genes. And now the repressions alleviated here and we |
|
| 51:46 | make the H one, right? successive generations of this salmonella, the |
|
| 51:51 | rights will have the H one right? So, you know, |
|
| 51:56 | , it came in with an H , you know, and divided and |
|
| 52:00 | and made H two of Jones. then this event occurs to change the |
|
| 52:05 | C uh arrangement. And so then generations are now make the H one |
|
| 52:11 | one F OK. And so uh is just showing you kind of a |
|
| 52:15 | up of it, same thing, ? So here again, you see |
|
| 52:18 | uh this right here, right? the promoter for the two genes um |
|
| 52:25 | the H two form, repressor, expression of the C form. |
|
| 52:31 | And we get the spontaneous read. right. OK. And then here |
|
| 52:38 | , here we are over here facing direction. We're not gonna get expression |
|
| 52:43 | that. OK. And so so the strategy, all right. |
|
| 52:48 | let's look at this question. All . So the strategy here, |
|
| 52:52 | Um The ah here here, hold the uh so we have, so |
|
| 53:00 | have, I have to shout while change my batteries. Um um So |
|
| 53:07 | have in this question, the infecting have are, are that population 1 |
|
| 53:15 | 1 H one H two flagella as , will that strategy work when affecting |
|
| 53:23 | human? And by working, think terms of is it best for it |
|
| 53:31 | salmonella to do this in terms of this human and being successful is just |
|
| 53:37 | best way to do it? Answer is uh yes or no. |
|
| 53:43 | . How is that uh test Hm. There we go. |
|
| 53:54 | So one more time. So this population, it's affecting our |
|
| 54:04 | OK. Half have H one half have H two. Is that |
|
| 54:10 | way to do it or is there better way and better? I |
|
| 54:13 | in terms of the salmonella? So , you're trying to be a, |
|
| 54:16 | , an inf affecting salmonella that will success? Ok. Good to be |
|
| 54:24 | . So see what we get. . So if you answered uh who |
|
| 54:43 | BB as in boy, B as boy, B as in boy, |
|
| 54:49 | , 200 or something that we Anybody, anybody brave enough, I'll |
|
| 54:54 | you an A for the day. you, that's up anybody. Not |
|
| 54:59 | again, anybody come on don't be anybody, anybody, anybody. |
|
| 55:09 | Why? Mm Right. So it's like uh playing poker, right? |
|
| 55:26 | you're basically playing poker by showing your to everybody. OK? You're not |
|
| 55:31 | them right? Close to the chest , right? You're showing, showing |
|
| 55:35 | what you got already, right? of course everybody's gonna fold, |
|
| 55:39 | They're not gonna, you have like aces, right? And you show |
|
| 55:43 | that you go. Oh well, out, right? You're not gonna |
|
| 55:45 | any money, right? Not So essentially that's what's happening here. |
|
| 55:50 | only, these are the only two of the engine, then the body |
|
| 55:53 | seeing everything, right? And so system cells are primed and ready. |
|
| 55:58 | don't recommend, you know, even it does change, if these guys |
|
| 56:03 | to A, to an H two these guys flip to an H one |
|
| 56:09 | matter. So it's already the body's seen it, right? So best |
|
| 56:13 | go in with mostly one engine then when you, when it flips |
|
| 56:18 | body is like, your body will to, there'll be a delay before |
|
| 56:21 | body can see it and catch And that's when pathogen can grow rather |
|
| 56:26 | . Ok. So that's, that's best way if you wanna be the |
|
| 56:31 | from the pathogen perspective. Ok. And Niia which is causes meningitis and |
|
| 56:38 | diseases is very famous for doing this it can, it can have more |
|
| 56:42 | two engines and like maybe 345 or engines and flip from one to the |
|
| 56:47 | . OK. Um Any questions about ? Yeah. All right. Uh |
|
| 56:53 | factor regulation. So this uh your book has probably about five or |
|
| 56:58 | examples of this. This, this is, is, is not, |
|
| 57:04 | not a transcriptional control, it's actually a little different. OK. And |
|
| 57:09 | we look at the this this heat or we call so in in response |
|
| 57:15 | high temp, OK, like E and other types um being a |
|
| 57:23 | right? They grow at 37 or . Um elevating temperature of course, |
|
| 57:29 | proteins, nucleic acids, right? temp in nature, proteins unfolding, |
|
| 57:33 | cetera, right? So not So you have to have mechanisms in |
|
| 57:38 | to deal with the stress. And you do, right? And |
|
| 57:43 | genes that are involved in that response turned on by a specific sigma factor |
|
| 57:50 | the heat. Uh it's a heat sigma factor. OK. Sigma |
|
| 57:55 | right. So rpoh is the name the gene that codes for that sigma |
|
| 57:59 | that you see there. OK. what happens is you get transcription? |
|
| 58:05 | and, but it's folded up, ? So you see the the transcript |
|
| 58:10 | folded, it's hiding that um ribosome site. OK. So the transcript |
|
| 58:15 | made uh but it's folded. So , when we're at 30 degrees, |
|
| 58:23 | ? So at 30 C folded OK. Which makes sense because in |
|
| 58:29 | state, you can't translate it. remember these things aren't permanent, it'll |
|
| 58:34 | mostly like in that folded up state 30 degrees where they can, you |
|
| 58:38 | , it can come apart occasionally and it does, you get a little |
|
| 58:42 | of expression. And so to kind take care of that little bit that |
|
| 58:47 | made, right? Because you don't a heat shock Sigma Factory if you're |
|
| 58:50 | , if it's not hot, So you want to minimize the effect |
|
| 58:54 | that. So you have these other here, they're called chaperone proteins. |
|
| 59:00 | DNA JJ R pe DK, And they sort to kind of bind |
|
| 59:05 | it and then, and then signal for degradation, get rid of |
|
| 59:09 | OK? They also have another those those chaperone proteins, they kind |
|
| 59:15 | um are also made during the heat response to bind to proteins that are |
|
| 59:22 | because of the heat. So they to them to kind of keep them |
|
| 59:27 | . OK. So just remember So step one here. So we |
|
| 59:30 | 30 degrees don't need heat shock proteins . So we, we produce a |
|
| 59:35 | for the heat shock signal factor that's up like temperature. The temperature is |
|
| 59:40 | keeping it in that form. So only very little of it gets |
|
| 59:47 | in the protein but the the the amount that does gets attacked by so |
|
| 59:53 | speak the chaperone proteins that will lead degradation. Ok. Now, of |
|
| 59:58 | , when it is elevated temperature, ? 42 OK, temperature goes |
|
| 60:04 | then you want the heat shock signal to do its thing. Turn on |
|
| 60:09 | genes that will help the cells right? So you see how the |
|
| 60:14 | elevated temp has straightened out, so speak the the transcript. So it |
|
| 60:21 | of has has melted apart, So now that can be greatly translated |
|
| 60:26 | protein. So you make lots of OK, which will then act on |
|
| 60:32 | , and, and uh promote expression the heat shock genes. So among |
|
| 60:37 | , so this guy doesn't get degraded these chaperone proteins like it did |
|
| 60:44 | right? Because they're busy dealing with the proteins in the cell that |
|
| 60:49 | that are being affected by the high , they're sticking to those guys and |
|
| 60:53 | them folded and keep functional. And so the sigma factor is free |
|
| 60:58 | do its thing, right? Because are, those other guys are, |
|
| 61:01 | occupied doing their doing that function. . Um And so this is um |
|
| 61:11 | let me say, dang it, forgot, I lost my thought. |
|
| 61:17 | Did I? All right? If comes back to me, I'll |
|
| 61:22 | Anyway. Um So this is an of not transcriptional control because we're making |
|
| 61:27 | transcript, right? We're making the , it's rather a condition of, |
|
| 61:31 | we going to allow translation to Right. Uh Are we gonna translate |
|
| 61:36 | thing? Right. And so um , in order to make lots of |
|
| 61:42 | ? OK. So more kind of into the basket of like translational |
|
| 61:48 | OK. Um OK. Uh I remember what it was anyway, so |
|
| 61:56 | questions about that. So it's kind temperature in a way is kind of |
|
| 62:00 | affecting things here. OK. Um RNAs. OK. So these |
|
| 62:08 | of course not just a feature of cars, but of all all life |
|
| 62:14 | in us as well. Certainly our A molecules serving gene control uh as |
|
| 62:20 | control mechanisms. OK. The first these small regulatory RNAs, so that |
|
| 62:25 | gonna talk about these and we're gonna about um what are called antisense |
|
| 62:31 | So these types occur between genes between coding genes. OK? Um The |
|
| 62:38 | type antisense are exist within the it controls, OK. So whatever |
|
| 62:47 | scenario, whichever type it is, more efficient because you're not having to |
|
| 62:52 | and translate to make a regulatory The RN A that is the thing |
|
| 62:58 | causes the effect. So, from standpoint, it's, it's, it's |
|
| 63:01 | more efficient and less energy using. . Um And so this is my |
|
| 63:10 | . So remember the RNAs can fold right in the secondary structure forming what |
|
| 63:14 | call these hairpin loops. OK. this one in particular is one. |
|
| 63:19 | these have these, these regulatory whether it's this type or any |
|
| 63:26 | it's all about homology, complementary base to a target. OK. And |
|
| 63:31 | they do that, they basically block , a ribosome from being able to |
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| 63:36 | . So it's either that effect or leads to the degradation of the RN |
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| 63:40 | . So typically, that's what both these types lead to. Whether it's |
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| 63:44 | the regulatory RN A is, either translation and or degrade it, |
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| 63:50 | Um And so the staph aureus um it is a pathogen and like many |
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| 63:58 | , they will have steps to their . Right. First part is about |
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| 64:03 | to the host and it's about let's divide and proliferate, then maybe it's |
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| 64:07 | damage. So there is a stepwise and it uses regulatory RNAs to kind |
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| 64:12 | control the steps. OK. So see the typical effect. So remember |
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| 64:19 | , all right, that's that shine Barno sequence, right? So here's |
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| 64:22 | target and this is where the Rhino binds, right. So there's gonna |
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| 64:26 | homology between. So this is the A three, it's called here is |
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| 64:35 | guy. So it's homology, So it's complimentary based pairing, it |
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| 64:40 | on that target and blocks basically right. Ribosome can bind. Uh |
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| 64:45 | can also lead to degradation. So, um and so this next |
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| 64:51 | , it really just shows you don't to memorize this. It's just showing |
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| 64:54 | how it can work, not just block expression to, but to promote |
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| 65:00 | . So it can act actually depending the type, it can work both |
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| 65:03 | allow expression or uh blocking thrash. . And so you can see that |
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| 65:09 | here is A and B in terms translation, inhibit basically what we just |
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| 65:13 | , right? It binds here, the regulatory RN A, it binds |
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| 65:18 | the target and no translation. Here a regulatory RN A and this is |
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| 65:25 | form of the transcript, it's So it can't be translated right? |
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| 65:33 | the regulatory RN A comes in binds it and now you free that binding |
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| 65:40 | . So it can be translated. it's working 11 works one way and |
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| 65:43 | works the other allow block translation or it. OK? And it's all |
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| 65:48 | about binding and changing the structure, , whether the structure can either be |
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| 65:53 | that prevents translation or opens it up allows translation or whatever. So here |
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| 66:00 | promoting degradation or preventing degradation, So we bind there's target binding, |
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| 66:08 | ? We get degradation here is if and preventing the RN A SRN A |
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| 66:15 | will degrade the RN A. So preventing the degradation. So, |
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| 66:18 | just examples of how you know it work both ways and it's all about |
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| 66:23 | binding to the target, right? allowing the effect or not allowing the |
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| 66:31 | . Um And you see other examples too, either promoting processing or uh |
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| 66:38 | of regulatory protein, right? So in this mode here, it we |
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| 66:46 | active translation uh by binding up the protein here. So we alleviate the |
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| 66:56 | on translation. Now, the RS binding site is free, we get |
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| 67:01 | . So again, you don't need memorize each one of these things. |
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| 67:04 | just makes it just know that it , it works through binding base pairing |
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| 67:10 | the target. And that binding can lead to the um expression of that |
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| 67:17 | that gene or blocking work both right? Um So the last one |
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| 67:25 | is antisense on this. This is be a little bit trippy. |
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| 67:29 | So um it's very common, especially bacteria. You can see over 1000 |
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| 67:36 | that's basically about a third of e genes are controlled this way. Um |
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| 67:41 | so, difference from the previous one that those small RNAs, those sequences |
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| 67:47 | between genes. This guy is right in the middle of the gene it |
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| 67:54 | . OK. And so uh and , I meant to take this out |
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| 68:00 | I posted these notes, but just that stop transcription from your notes. |
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| 68:06 | ? It doesn't do that. the effects of these RNAs are either |
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| 68:09 | translation or degrade transcript, right? , um all right. So here's |
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| 68:16 | protein coding gene. OK. So we have a plus the plus minus |
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| 68:21 | , right? We have plus coding and a minus pi strand. |
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| 68:25 | So in the plus strand, all , will be the ants rnac, |
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| 68:32 | ? So right there uh because it's the plus, it in itself is |
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| 68:36 | plus. OK? And I just in the four base is just a |
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| 68:40 | of, you know, it's It's about complementary base pairing. All |
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| 68:44 | . So what happens is um there's four bases of the complementary anti |
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| 68:51 | OK? So when we express whatever this is coding for, we do |
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| 68:57 | usual process, right? We're we're gonna copy the template strand, |
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| 69:01 | minus strand and make a plus right? That's our transcript. |
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| 69:06 | And that's what we've done, This is our, this is our |
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| 69:10 | and we're gonna make translate that in protein, right? Whatever it |
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| 69:14 | whatever this one, this gene OK. Now, if you wanna |
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| 69:18 | it, OK, what we do we copy that plus antisense gene, |
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| 69:26 | ? We're gonna copy that strand. ? And of course, when we |
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| 69:33 | that, we're gonna make a minus , right? And So that minus |
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| 69:39 | is right here, right? Minus that's gonna be complimentary, right? |
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| 69:46 | , remember it's G TT A Um Complementary strand will be CAA |
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| 69:55 | right? And so you will get base pairing there and it'll bind to |
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| 70:01 | transcript of that gene and only of gene and thereby controlling expression, either |
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| 70:08 | translation being it being degraded. So that's the thing about these |
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| 70:15 | it can only control the gene sitting . OK. Um But the net |
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| 70:22 | is the same as with, with , with all regulatory RNAs bind to |
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| 70:28 | target block translation or, and, they degraded. OK. All |
|
| 70:35 | Um Any questions about that? So let's look at this question |
|
| 70:43 | Right. Yeah. Damn it, . OK. Uh OK. Which |
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| 70:53 | not correctly matched, right? This back to type of control. Does |
|
| 70:58 | fit? OK. Mhm Let me here at 10. So remember post |
|
| 71:50 | was kind of an umbrella term. . Um But there is one that's |
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| 71:57 | not correct at all. So let's . 10. Got number 10. |
|
| 72:10 | . Thank you. Oops, stop at one. Let's see. |
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| 72:20 | All right. OK. If who answered B as in Buster, |
|
| 72:31 | did you pick B phase variation that ? Mhm Right. So basically phase |
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| 72:41 | phase ation is at the level of DNA is level of control. |
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| 72:46 | So, but cation transcriptional, stringent , each shot, posttranscriptional, you |
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| 72:53 | be further specific and say it's translational it is posttranscriptional. OK. Uh |
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| 73:03 | sensor is translational also be MRN a , right? It, it degrades |
|
| 73:08 | . OK. So, all right . That's it. See you next |
|
| 73:13 | . Yeah, I'm sorry. Oh . Yeah. Yeah. Yeah. |
|
| 73:31 | phase variation is like free transcription. could say that. Yeah. Uh |
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| 73:37 | , |
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