| 00:00 | Welcome folks. This is the second of the Chapter three material, or |
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| 00:06 | cover the rest of the functions of pro chaotic cell structures and functions thereof |
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| 00:14 | recall that they're starting learning objectives for section of course. And so again |
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| 00:22 | use these as a checkpoint checklist just make sure you're familiar with each of |
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| 00:29 | and you know, just kind of a guide um for what you should |
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| 00:35 | after having finished this um module. , so here we're going to so |
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| 00:42 | time we talked about um really the to sell envelope um inter membrane |
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| 00:52 | gram negative, gram positive, um micro bacterial cell wall um so kind |
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| 01:00 | ending with capsule uh structures external to cell wall. Um So um um |
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| 01:09 | capsules, slime layers and biofilms. now we're basically going internal right internally |
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| 01:16 | going on in the structures and functions the cell more or less. And |
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| 01:21 | here we're starting with several skeletal So I'm sure you're quite familiar with |
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| 01:28 | the eukaryotic side of skeletons. So just showing you kind of uh as |
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| 01:32 | a recap of this, what you've before uh and the extensive network of |
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| 01:40 | , filaments that are common to eukaryotic are quite extensive network, highly specialized |
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| 01:49 | varied functions. Right? So we we call that, you know, |
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| 01:54 | tubules and actions are typically um involved certain types of motion um Structural |
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| 02:04 | Uh and we found what's been found that in precarious, this has been |
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| 02:10 | the last 10 years or so. found that there are analogous psycho skeletal |
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| 02:15 | of bacterial cells now by no means that the kind of extensive network you |
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| 02:20 | there? Because of course a lot these in the eukaryotic cell. A |
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| 02:24 | of these function in conjunction with organelles different types in many cases. And |
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| 02:28 | of course bacteria don't have that and involved in in replication division of the |
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| 02:34 | . So uh but nonetheless cells have found to have some of these um |
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| 02:41 | skeletal elements for functions typically involved relating um whether it's a cell wall |
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| 02:49 | some aspect of replication um like the synthesis uh the division of the cell |
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| 02:59 | uh these kind of processes and sometimes form shape of itself. So this |
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| 03:03 | kind of where we see the functions this bacterial psycho skeleton. And here's |
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| 03:08 | example of the one where you know of there was an idea that maybe |
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| 03:12 | was some kind of psycho skeletal element in mutants of bacillus, bacillus or |
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| 03:17 | shaped bacterium of mutants in this with in this M. R. |
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| 03:23 | B. Uh component which is analogous homologous to acting filaments that we see |
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| 03:32 | new carry those. Um And we M. R. E. |
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| 03:37 | Previously in the synthesis of like on that occurs in cells and so acting |
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| 03:47 | kind of like a scaffold to guide whole process is the protein complex. |
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| 03:52 | nonetheless you know when they found out were mutants in these, you see |
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| 03:55 | non mutant type on the on the and the typical rod shaped bacterium that |
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| 03:59 | the right, lacking the M. . E. B, would come |
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| 04:02 | with these basically circular shaped cells. that became an inkling that, you |
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| 04:07 | , subtle skeletal elements are involved here so again. These are four uh |
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| 04:13 | know, writing, shape and form could uh may provide protection and other |
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| 04:20 | . There's still a lot of being with these elements but certainly in terms |
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| 04:24 | shape, form and contribution really in aspects of cell division. Cell wall |
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| 04:31 | . Okay, so the FTS dizzy is one that's found in um I |
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| 04:40 | most all bacterial cells whether your poxy rod shape or what have you. |
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| 04:47 | It kind of it's in the middle at the cell, so it kind |
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| 04:50 | defines the cell diameter uh informs a called the ring. That is important |
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| 04:57 | ation of the cell. So when cells divide, uh bacterial cells |
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| 05:02 | you have expectation also archaea in the way you have a septum form that |
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| 05:07 | splits the cell. Okay, And F. Tsz ring is instrumental in |
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| 05:13 | . Um Now, in addition the may have it's a rod shaped |
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| 05:18 | it may have things like M. . E. B. Which um |
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| 05:23 | is uh within the hair cell membrane near it and bringing about the formation |
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| 05:32 | cell wall material. Okay, we that earlier. How contributes to |
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| 05:37 | And so there's arcs of this material the rod shaped cell and that's how |
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| 05:44 | uh has so often synthesis occurring um college factor, which is a what's |
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| 05:53 | they comin shaped or crescent shaped Vibrio is a term we often hear |
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| 06:01 | for sales with the shape. Um have of course the F. |
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| 06:05 | S. Z. And so note that is comin right to each of |
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| 06:13 | cells here because it's gonna be insect ation. Okay, so we |
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| 06:17 | that but also the present in in common shaped cells forms right here on |
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| 06:24 | side. Okay, so it kind bends the cell on that side to |
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| 06:30 | this kind of common shaped cell. we see how the skeleton kind of |
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| 06:36 | to maintain form and shape of the and assist in cell wall synthesis. |
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| 06:42 | So here further with cell division. . And the production of this device |
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| 06:48 | complex. Okay, that forms uh part of this um side of skeletal |
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| 06:56 | . And so again, expectation processes splits the cell into. And you |
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| 06:59 | see there with a the caucus shaped sell that the pinching in occurs septum |
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| 07:08 | inward. You see it here and this side and they're gonna meet in |
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| 07:13 | middle creating two selves. Okay, so that occurs there's the F. |
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| 07:21 | complex, that's in the middle of cell um and then bringing uh so |
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| 07:28 | the opposite end of the same things . So we're gonna meet in the |
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| 07:31 | and create that uh septum that will the cells. Okay. And so |
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| 07:36 | course this is going on. You a rapid synthesis of everything that's in |
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| 07:40 | cell envelope. So if your gram , you know, you have the |
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| 07:43 | membrane and you have of course the I can in the middle and the |
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| 07:47 | plasvic space. So that is all synthesized. Um And as I |
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| 07:52 | is the septum forms and then splits cell into. Okay, And they |
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| 07:57 | that complex a uh device um Okay. And so in in a |
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| 08:05 | shaped cell you have just the ftse . You don't have the M E |
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| 08:10 | B M R E B component is you see in the rod shaped |
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| 08:14 | Okay. Um so uh and so so we go from then and we'll |
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| 08:24 | we'll revisit segmentation and cell division in little bit as we talk about in |
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| 08:31 | context of DNA replication. So we'll back to this a little bit. |
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| 08:36 | uh so nuclear Lloyd. So the nuclear would first and foremost is |
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| 08:41 | an organ l there's there's no membrane the chromosome. Okay, so it |
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| 08:48 | is an area occupied by that um . Okay, so bacteria of course |
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| 08:58 | um excuse me, I have a servant of chromosome there's variations, but |
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| 09:06 | few. But most will have that circular chromosome. And um again about |
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| 09:13 | 5 million base pair, average size size range. And um but of |
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| 09:20 | many loops are occurring in the chromosome help keep it contained inside the |
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| 09:26 | Uh DNA binding proteins. There's an which is the origin of replication that |
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| 09:31 | going to be attached at the central of the cell. Okay so the |
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| 09:36 | Tsz psycho skeleton plays plays a part and kind of orienting with the origin |
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| 09:44 | story. And um at the middle the cell and you see there the |
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| 09:51 | kind of has loops and folds they domains. Um some parts are gonna |
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| 09:56 | more uncool than others because of course to be transcription going on transcription, |
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| 10:03 | and somebody else. Some parts of D. N. A. Continuing |
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| 10:07 | being being transcribed and translated. Others . So it's gonna be different degrees |
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| 10:12 | coiling. Um super calling, carried by DNA gyre ace to help construct |
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| 10:19 | and make it fit as well as binding proteins to kind of keep it |
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| 10:23 | together. But there is an attachment at the origin uh to the inner |
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| 10:29 | of that inner side of that cell . Now transcription translation. So um |
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| 10:38 | in precarious it's um so remember that is the flow of information right from |
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| 10:43 | . N. A. The Genes uh that's transcribed into RNA. |
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| 10:48 | then it's finally translated into protein. ? Essential process of any living |
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| 10:54 | So in in precarious this process is in other words they can occur virtually |
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| 11:03 | . Okay and that's because prokaryotes lack nuclear membrane. There's no remember in |
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| 11:12 | in new carrying a nuclear membrane creates partition that separates transcription from translation. |
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| 11:20 | occurs outside the nucleus. In the the side is all. So in |
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| 11:26 | they there's no such barrier. And um as we can see here so |
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| 11:33 | the diagram on the right we see portion of a cell and we see |
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| 11:38 | chromosome and we see these little we these red circular bean shaped structures. |
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| 11:44 | are ribosomes. Okay that's uh these are ribosomes. And then the um |
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| 11:54 | and blue is the M. N. A. S. So |
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| 11:57 | the M. RNA is blue and gold is the protein peptide sequence being |
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| 12:04 | . Okay so I'm just gonna show here on the left. So a |
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| 12:11 | of it has been circled. That's the policy zone. Okay so |
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| 12:15 | policy was basically the structure containing a ribosomes on the transcript and translation occurring |
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| 12:23 | those ribosomes. Okay so here is segment of D. N. |
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| 12:33 | And races what brings about the transcription form a messenger RNA. Okay and |
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| 12:40 | once that M. R. A. Begins to appear. And |
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| 12:44 | remember this is going to be the prime end as soon as that appears |
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| 12:52 | actually a sequence here, it's called ribosome binding site R. B. |
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| 13:00 | . For short ribs um binding site appears. And once it appears ribosomes |
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| 13:05 | begin to bind to that transcript. as you see there it binds and |
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| 13:10 | begins to travel To three prime And of course synthesizing protein translation is |
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| 13:18 | . Okay so you see the poly chain coming out of there and so |
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| 13:24 | as one goes another one then will bind to the transcript. So we're |
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| 13:29 | have multiple ribosomes all along the length that transcript. And of course the |
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| 13:36 | of the pipe peptide chain is increasing it gets toward the three prime end |
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| 13:42 | is over here that um that's the of translation. So the pipe peptide |
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| 13:55 | going to be longer as you're going the three prime end. So what |
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| 13:59 | means is we have a a tremendous of cooking sentences that can occur at |
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| 14:06 | given time. Um This again is of the several reasons why bacteria can |
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| 14:11 | so fast is in order to grow . You have to make you have |
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| 14:16 | make your sailor material very quickly if gonna grow quickly. And that means |
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| 14:20 | of protein synthesis and that's exactly what can do with this policy zone polly |
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| 14:26 | mechanism and basically having transcription and translation together. Um lots of protein being |
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| 14:34 | from its various genes it needs very . Okay and of course it's all |
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| 14:39 | control so we can stop it all once as well. Stop it when |
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| 14:42 | needs to. So make sure a efficient uh system and and very able |
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| 14:48 | keep pace with fast growth. Um of course uh you're gonna have proteins |
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| 14:55 | are synthesized in in the cytoplasm um are for functions in different metabolisms. |
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| 15:02 | you also have proteins that will need go to the the membrane cell wall |
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| 15:09 | or or outside the cell. And what these that's what the synthesis up |
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| 15:14 | is all about the srp or signal proteins that recognize sequences on proteins being |
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| 15:23 | that require them to be in the or outside the cell. Okay, |
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| 15:30 | really what that's about. So those for proteins that are for those functions |
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| 15:33 | membrane functions or extra cellular functions. , so synthesis is completed at the |
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| 15:42 | now uh cell division. So the when we compare eukaryotic division to pro |
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| 15:53 | division, what you call fish in division is mitosis. Okay, the |
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| 15:58 | products are the same. Okay, you see a simple eukaryotic cell with |
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| 16:02 | chromosomes. Remember you carry out linear and the appropriate with a single circular |
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| 16:09 | . So the end product of both the production of clones right, genetically |
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| 16:14 | daughter cells. Um Now mitosis is vision, their mechanistic mechanistic lee they're |
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| 16:22 | different. Okay so of course they any cell does as dividing. And |
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| 16:29 | have to segregation the chromosome and you the partitioning, it's just more complex |
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| 16:34 | you carry out. So you have phases. It goes through to um |
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| 16:40 | copy the chromosomes. Uh segregate And in order to make sure that |
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| 16:49 | have genetically identical cells and bacteria. not that complicated, right? You |
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| 16:56 | um you do hold on to the at the story. Uh and that's |
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| 17:00 | of that's kind of uh controlled by F Tsz, that's in the middle |
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| 17:07 | the cell. Should be right. that cyber skeletal element will help keep |
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| 17:13 | happening so that it ensures each half the cell gets a copy of the |
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| 17:18 | . But again, it comes fairly and you carry outs, the time |
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| 17:22 | is 10-24 hours, maybe less in you know, cells that are like |
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| 17:29 | zygote that is dividing through Early stages development can be growing rather quickly for |
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| 17:36 | carry out that can be on the of maybe eight hours uh for a |
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| 17:40 | to divide. But for precarious, much faster we're talking, it can |
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| 17:44 | upwards of even a little less than minutes to as much as two |
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| 17:49 | That's about the average time. It be it can be longer than |
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| 17:52 | But for most it's kind of in time frame. So again, you |
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| 17:56 | , having that lots of reasons for small size, small chromosome. Um |
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| 18:02 | as much material to keep up with the policies own formation to produce lots |
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| 18:07 | proteins quickly. So all these factors why they can grow so fast. |
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| 18:12 | So in terms of replication, um all about the story sequence origin of |
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| 18:19 | , that's where replication initiates initiates. it's where strand separation occurs. |
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| 18:26 | remember it's gonna be it's gonna be attachment to the inner side of that |
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| 18:32 | memory. Okay. At the ori that's kind of how the cell holds |
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| 18:36 | to it. And the ftse complexes involved in that as well. I |
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| 18:41 | to help coordinate that. And so you see there as the strands open |
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| 18:45 | , you begin to get DNA synthesized remember that when you open them up |
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| 18:49 | create two replication forks and then a called the replicas um attaches at each |
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| 18:57 | . And each each rep is um two D. N. A polymerase |
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| 19:02 | okay because remember your DNA replication, you're copying at each fork, You're |
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| 19:09 | to copying the leading strand and the strand. Okay, so you're gonna |
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| 19:13 | to have a DNA plagiarize for each . Alright, so to represent contain |
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| 19:21 | DNA plum arises at each fork that then move away from each other as |
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| 19:26 | see by the direction of the This is bidirectional replication. So um |
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| 19:35 | will terminate at a sequence called the sort of red. And that's where |
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| 19:39 | complex will fall off and then you to complete copies of the chromosome. |
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| 19:44 | , so we go back to the . Excuse me. So you see |
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| 19:52 | soon as the Koreans copied, we the generation of so the orient gets |
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| 20:01 | and then also attached to the underside that saddle, plastic plasma memory. |
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| 20:10 | both both are kind of in proximity each other in in the middle of |
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| 20:14 | cell. And so from there we uh the copying. And so you |
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| 20:20 | the two referees owns here and they continue to copy uh strand the chrome |
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| 20:27 | . And then you see the ftse forming there in the middle of the |
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| 20:30 | . That's what brings about this dissertation the cell. Okay, So what |
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| 20:36 | note is that and I'll show you animation. What you notice is that |
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| 20:40 | before we've completed the first round of ? Right. Which is what's going |
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| 20:46 | happen here, You see before they already begun the next round. |
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| 20:54 | So it's as if the cells Okay, thinking a step ahead |
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| 20:59 | Right, So we know that one makes 22 cells make four. So |
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| 21:03 | already at the step here where it's primed to make four cells already, |
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| 21:08 | after the first two have been So again, that's why it can |
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| 21:12 | . That's why growth can happen so because of a process happening like |
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| 21:16 | Right? So you see the zeroing uh forming to create the expectation of |
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| 21:23 | cell. And it's the plane of ation kind of determines um uh the |
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| 21:34 | arrangement themselves. So whether you have cock C. Or whether you have |
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| 21:39 | or you have what are called tet , that kind of goes by the |
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| 21:44 | of the way the septum forms. . And then the plane form so |
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| 21:49 | are perpendicular to each other, or parallel that can kind of give you |
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| 21:52 | arrangements depending on the species. um now let me just show you |
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| 22:00 | real quick. Okay, so here's animation. And you have access to |
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| 22:10 | as well. So here is our chromosome and the story sequence. And |
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| 22:22 | uh the first part is for the to separate. And so you see |
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| 22:26 | they do, we're generating uh synthesizing . N. A. And we're |
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| 22:31 | copy that sequence. And then that automatically be bound to the inner half |
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| 22:37 | that cell membrane. So now we our two stories and we're beginning to |
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| 22:41 | , copy our chromosome. And so a replication forks and we continue |
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| 22:51 | So there's a repo zone two of each with two summarizes and we continue |
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| 22:58 | . Right? So bi directional So you see we've already even before |
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| 23:05 | finish we have ribosomes being bound to going to be the next set of |
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| 23:13 | and splitting the two cells. And this one is almost done replicating. |
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| 23:21 | we'll form forces very quickly. And before we get done here, they'll |
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| 23:25 | be two more repos OEMs attaching as . So that's why we can get |
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| 23:30 | process. And so dissertation process occurs uh as you saw there, except |
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| 23:37 | again, F Tsz is instrumental in process. So it allows for so |
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| 23:43 | can replicate very quickly because the chromosomes so fast now. The phenomenon of |
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| 23:53 | aging. Okay, so particularly, know, in in uh rod shaped |
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| 24:01 | , uh you might wonder, is there cemetery is there is there |
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| 24:05 | other differences at polls of the And of course we can think of |
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| 24:10 | bacteria that may happen for them on end and on the other. So |
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| 24:14 | an example of a cemetery in the . Right? So that so that |
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| 24:20 | even without something obvious, you can have differences at the polls that maybe |
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| 24:24 | visibly obvious but can be differences in of the constituents that are at each |
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| 24:30 | . Okay, so in polar that phenomenon is about, you |
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| 24:36 | expectation occurs from the cell division that have what are called old and new |
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| 24:43 | . Okay, so you see here terms of blue versus red, that |
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| 24:52 | red indicates the old poles and blew new ones. Okay, so as |
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| 24:59 | replicate. Right? These this and will become new polls as you see |
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| 25:06 | . Okay. And these are kind aged, right? That was a |
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| 25:09 | poll at the beginning after it split now it's it's going to become what |
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| 25:14 | call old. Okay. And so have cells in the population in any |
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| 25:20 | population that have different proportions of old new polls. Okay. And um |
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| 25:27 | you can see that as the generations here. Right. And so what |
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| 25:32 | can happen at the older poles is tends to be a scenario where it |
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| 25:41 | um uh proteins, nonfunctional proteins and cells and they can aggregate stress aggregate |
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| 25:53 | , nonfunctional proteins at one. Uh older poll um the cell wall material |
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| 26:00 | to degrade at the old poles more than newer polls and that can make |
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| 26:05 | susceptible to license um Exactly why this is not sure. But um the |
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| 26:14 | poles because I guess you can participate cell division once that pull will will |
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| 26:22 | and can accumulate these these kinds of functional proteins and things so that I |
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| 26:30 | contribute of course to to the death the culture eventually. Um And so |
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| 26:36 | it also can make it for a that may have different because portions of |
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| 26:41 | the new polls within the within the can influence perhaps maybe resistance to |
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| 26:49 | you know, maybe a greater proportion older poles makes it less acceptable or |
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| 26:55 | resistant to antibiotics. So there there's evidence to support that now if we |
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| 27:01 | at um these three genera bacillus, back chairman color backed er uh just |
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| 27:10 | at a symmetry in in rod shaped , bacillus has um endospore former. |
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| 27:18 | and so uh they of course can a spore at one end. Not |
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| 27:22 | of them do but many can form former spore at one end of the |
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| 27:27 | of course creating an a cemetery. Qallab actor uses what's called a stock |
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| 27:34 | can have a flagellum depending on what environmental conditions are. So that's the |
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| 27:40 | of a cemetery the karate Bactrim shares other members of that group. This |
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| 27:47 | morphology called cleo morph. Okay and you see there is kind of polymorphic |
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| 27:54 | don't have a uniform shape. They're of called club shaped uh irregular |
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| 28:00 | And this has to do with uh differences at the poles where it's not |
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| 28:07 | . And you get this kind of irregular forms. And corona bacterium is |
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| 28:11 | for that corona bacterium, diphtheria um a disease causing type causing diptheria of |
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| 28:17 | . But that that's graphic just showing kind of some different arrangements of cells |
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| 28:24 | that you know uh coxon rods that is in in chains or in in |
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| 28:31 | or in tech dress. And these of shapes are due to the plane |
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| 28:35 | cept ation when they divide and kind how they're oriented to each other after |
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| 28:40 | divide whether they form these kind of or not. Okay so there's a |
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| 28:46 | of course of shapes among bacteria. so um so here we look at |
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| 28:55 | some specialized structures and um uh and these we can put in the category |
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| 29:07 | either you know specialized structures that are of a particular type of metabolic |
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| 29:13 | A microbe may have. Um They also fall in the category of uh |
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| 29:20 | fruit storage or any energy storage Um uh So kind of in one |
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| 29:29 | those types of functions. Okay by means does anyone bacterium have all these |
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| 29:34 | ? Okay so certainly the first of we call structures that relate to um |
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| 29:40 | being an autotrophs if in some cases photo water trough. So remember that |
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| 29:45 | autotrophs are those that um rely on light uh conversion of light to chemical |
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| 29:55 | or oxidation of inorganic materials without using uh to get energy. So that |
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| 30:03 | your photo tropes and little tropes. then the energy is used from those |
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| 30:09 | to fix C. 02. Right these are your classic autotrophs. They |
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| 30:12 | be photo autotrophs or they can be or little autotrophs we call it. |
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| 30:18 | and so those those members of those can have these structures like Tyler coins |
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| 30:24 | example that you'd only find a photo because style opioids um continue light absorbing |
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| 30:31 | photosynthesis uh they're they're not organized as chloroplast organelles like a U. |
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| 30:38 | Radio. But there but there are of the cell's membrane that that are |
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| 30:45 | with these photosynthetic components and we call coins. The car box zones. |
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| 30:52 | again valid coins are not organized. not chloroplasts. Okay. They're just |
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| 30:57 | folding that can that are packed with photosynthetic components. The car boxy zones |
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| 31:04 | could be found you know in certainly traps because they're going to fix |
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| 31:09 | 02. But it can also be in in in may be found in |
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| 31:14 | Trust because it's it's about CO two and CO two fixation can occur oughta |
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| 31:20 | whether it's with light or without light on the type. And so but |
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| 31:24 | it's very active in in doing the . 02 fixation uh the enzyme that |
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| 31:29 | it out, it's called rue Biscoe short, it's short for rubio's 15 |
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| 31:33 | phosphate. This is the enzyme that takes the C. 02 molecules from |
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| 31:37 | atmosphere and combines it with a with sugar as part of the process we |
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| 31:44 | the fixation reaction. And so uh are particularly active in this can actually |
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| 31:49 | that enzyme packaged in high numbers in protein covered bodies that are called car |
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| 31:56 | zones as you see there in the . Um So additionally you may have |
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| 32:01 | gas vac you'll quickly in aquatic aquatic synthesizers, aquatic autotrophs. This is |
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| 32:12 | is uh certainly possible in order in to maintain proper depths in the water |
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| 32:18 | for optimal absorption of light. So photo tropes will have different optima of |
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| 32:25 | light they absorb. And that's of going to vary in terms of what |
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| 32:30 | is in water because it all depends how far light can penetrate. So |
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| 32:35 | vacuum, they can adjust their depth the amount of gas in their vesicles |
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| 32:43 | up or down for example to get optimum depth. So again that's something |
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| 32:48 | would find likely in a photo trophy depends on light of course. Uh |
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| 32:54 | it's different types of energy slash storage . So meta chromatic Granules there's karate |
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| 32:59 | again, so they're famous for having monochromatic Granules, they stained bright blue |
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| 33:05 | methylene blue. Um and what they are polymers of phosphate. So they |
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| 33:12 | as a quick energy store. Uh clipping off a phosphate group adding it |
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| 33:19 | A. D. P. To A. T. P. So |
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| 33:20 | a quick energy source for the cells have them and probably saccharine Granules. |
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| 33:28 | like glycogen and starch. Uh you're with these plumbers of glucose. We |
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| 33:33 | these implants, but there are bacteria can contain these as well, sulfur |
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| 33:40 | . So sulfur metabolism uh for bacteria can metabolize oxidize hydrogen sulfide. Uh |
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| 33:49 | can vary by species, some some produce the elemental sulfur as a result |
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| 33:56 | insoluble uh Some cell types hold onto as this one does. It's the |
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| 34:02 | Granules are those insoluble elemental sulfur others release it out of the |
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| 34:09 | Um Others can actually take that elemental and and further oxidize it. So |
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| 34:16 | just depends on the particular species. it's possible to certainly see those Granules |
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| 34:21 | certain of these cell types. Um inclusions can be things like PHP. |
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| 34:27 | you see there which stands for poly . Uh The yellow box is basically |
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| 34:35 | repeating unit of the lipid. And see their bacillus with these large white |
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| 34:41 | Granules or inclusions. These are full ph b. So these can act |
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| 34:46 | course lipid is a energy source. so we can use that as an |
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| 34:50 | source uh for growth. Um So here are specialized structures. So |
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| 34:58 | magnetic zones are not uh nutrient Okay, These are specifically for |
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| 35:06 | Okay so magnetism is involved in magneto taxes is any kind of a movement |
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| 35:12 | chemo taxes. Photo taxes. That magneto taxes movement along movement in a |
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| 35:20 | field. Okay. And so the that possess these have magnetite crystals. |
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| 35:27 | so the orient them in the magnetic . And if depending on what side |
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| 35:32 | the equator on on the north in northern hemisphere you'll move toward north and |
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| 35:38 | . If you're in the southern you'll move downward and south southward. |
|
| 35:43 | . And so what's believed going on is that these bacteria have um It's |
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| 35:50 | related to their the way they use . Okay so they're what we call |
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| 35:56 | I'm sorry. They're they're either anaerobic their micro era filic. Okay and |
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| 36:02 | relates to the whether they need oxygen they don't they're considered an Arabs if |
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| 36:10 | if they if they do require oxygen respiration but but they can only handle |
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| 36:17 | levels too high level is toxic then call them micro era files. Okay |
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| 36:22 | micro files re spire using oxygen. just have to have it at lower |
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| 36:26 | so it's not toxic to them. these bacteria are typically aquatic and so |
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| 36:34 | need to seek the right depth. so remember that oxygen concentration and water |
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| 36:38 | vary by depth. So typically if go lower in depth um auction concentration |
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| 36:45 | go down higher in depth. Typically higher oxygen concentration. So it uses |
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| 36:51 | magneto taxes to kind of get to in the water where the oxygen levels |
|
| 36:58 | optimum for them whether they need low or none at all. Okay so |
|
| 37:04 | that will help you to adjust to um pillai from brie and stock. |
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| 37:12 | are comprising the same component. It's pylon. Um Typically from bri I |
|
| 37:21 | tend to be more um numerous um tend to be what you might call |
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| 37:28 | a specialized category that can be longer less numerous. Um Both the function |
|
| 37:37 | it's or for attachment. Okay. can also be a kind of related |
|
| 37:42 | that occurs with that attachment called twitching . Uh These are very important in |
|
| 37:49 | formation. So bacteria the biofilm formers have this and if they lack them |
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| 37:54 | will not form a biofilm. So sex pilots is an example of a |
|
| 37:59 | pilots involved in congregation. You see so that's where genetic transfer of information |
|
| 38:05 | cell types. Um The stock that see in this bacterium. Uh This |
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| 38:13 | one that is um related to uh levels. So in areas so this |
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| 38:22 | again an aquatic organism a bacterium. in aquatic areas where nutrients are plentiful |
|
| 38:31 | will form a stock and what's called hold fast to make it in |
|
| 38:37 | stick to a surface and be a there. And basically just be in |
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| 38:41 | area of optimal nutrition of nutrients where can just use those um and proliferate |
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| 38:48 | when nutrients become scarce in that area they will lose that stock and possess |
|
| 38:55 | flagellum will form in its place and will become motile. Obviously seeking um |
|
| 39:03 | rich uh environment. Okay so it's of a nutrient driven phenomenon. And |
|
| 39:09 | going to see a number of those semester in terms of you know nutrients |
|
| 39:12 | either either plentiful nutrients or lack of creating a certain type of behavior phenomenon |
|
| 39:19 | the bacterium biofilm. That way biofilms as a result of lots of nutrients |
|
| 39:26 | present. And and those four forms the in contrast because it's there's a |
|
| 39:30 | of nutrients or that can be one the one of the reasons. So |
|
| 39:34 | know with nutrients present or absent that have uh influences in terms of different |
|
| 39:40 | of structures and things we see in certain bacterial types. Um So the |
|
| 39:47 | motility is um related to the specialized to pilots. And so we see |
|
| 39:54 | here. Um So it's about, all about first and foremost surface attachment |
|
| 40:01 | its surfaces where again so you see this bacterium its pilots and it's on |
|
| 40:07 | surface and the and the pilots problem as it does. So it extends |
|
| 40:13 | you see there from here to And in doing so it will then |
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| 40:22 | at a point and then it will rise so it will retract. And |
|
| 40:27 | you see the dash line, how is actually moving right from there to |
|
| 40:33 | like so. Okay and so we extension two prelim ization. Then we |
|
| 40:40 | rise and the net movement forward. it kind of has a it's not |
|
| 40:44 | smooth movement as it's going across. it kind of is a herky jerky |
|
| 40:50 | hence twitching. A pilot goes attaches Diploma rises, moves forward and |
|
| 40:57 | the process. So that's not really smooth motion. That's what they call |
|
| 40:59 | twitching motility but it's all about movement the surface. Okay an attachment to |
|
| 41:05 | surface here you see the same So alternating between attachment pulling and then |
|
| 41:13 | and moving in different directions. Okay here there's certain bacteria that can form |
|
| 41:22 | of their cell envelope and make connections other members of the population. And |
|
| 41:29 | doing so they can share proteins um . Um In some cases it compete |
|
| 41:38 | different species and there's been cases where resistance has been transferred in the same |
|
| 41:43 | . So there are types that can this and we call these extensions nana |
|
| 41:48 | through which this material passes a relatively phenomenon that's been discovered flagellum plural |
|
| 42:01 | I'm sorry singular plural. Um So . The bacteria is a motion in |
|
| 42:08 | eukaryotic cell is quite different. So it's a mechanism um that produces a |
|
| 42:19 | that's more of a wave type So think of a sperm flagellum. |
|
| 42:24 | motion is as a wave bacterial motion where the flagellum is rotating. So |
|
| 42:30 | more like a propeller rather than a . And so um the system itself |
|
| 42:37 | composed of this flagellum protein. Um I recall that with the cell envelope |
|
| 42:46 | a gram negative, we had that membrane component, the O engine. |
|
| 42:53 | called the O engine. Here we the flag Ellen protein. So that's |
|
| 42:57 | H. Engine we call it. it means is that um the |
|
| 43:01 | And O. Or historical designations. the H. Is the system itself |
|
| 43:07 | produce an immune response. And so have um uh antibodies to a number |
|
| 43:12 | these different proteins and we can identify bacteria. This is mainly for e |
|
| 43:18 | and salmonella types that are disease We can identify them through their H |
|
| 43:24 | using genealogical reactions. Um There can different arrangements of flagellum on bacteria. |
|
| 43:33 | as you see there there can be what we call polar flagellum at one |
|
| 43:38 | , it can be multiple at one , there can be one on either |
|
| 43:42 | that can be all around the periphery the cells. So all types are |
|
| 43:46 | and that can actually be used as criteria for identification as well. Um |
|
| 43:52 | the basic structure is and here we're at a gram negative cell. And |
|
| 43:56 | say that because we have an outer inner membrane and that para plastic |
|
| 44:00 | But gram positives can be motel as . The um structure contains this basil |
|
| 44:10 | which is anchored into the plasma membrane cell wall and a rotating hook that |
|
| 44:19 | a propeller motion of that um flagellum it's all of course. Andrew requiring |
|
| 44:29 | a tps to move it. But a process. It's a chemo tactic |
|
| 44:36 | process that's driven by the presence of . Okay. And so it's about |
|
| 44:45 | motion comes about through the uh proportion what are called runs to tumbles. |
|
| 44:55 | . And so what that refers to the rotation of the flu or flu |
|
| 45:02 | And whether it's clock, counterclockwise shown by counterclockwise, they are all in |
|
| 45:11 | . So for general martin sink and move in a smooth motion, rotate |
|
| 45:16 | in unison and form a smooth straight motion called a run. Okay. |
|
| 45:24 | opposite of that are what we call rotations of the flu gela and that |
|
| 45:29 | a tumble. Okay, So what it is the presence of attractants. |
|
| 45:40 | . And there are receptors on the pulling the cell that will if president |
|
| 45:45 | to the attractant and that will initiate increase the frequency of counterclockwise runs. |
|
| 45:52 | , more attractive present, increases the of runs. Okay, less or |
|
| 45:58 | attractant increases the frequency of tumbles. , so in a tumble, what |
|
| 46:04 | see if you have a run then a tumble, it'll kind of be |
|
| 46:11 | in place. Yeah, alright, then go off in some direction, |
|
| 46:21 | , whatever it may be. All , And then it can continue maybe |
|
| 46:25 | a straight line run and then tumble and then move and tumble again. |
|
| 46:32 | the idea is that by tumbling and off in a random direction that maybe |
|
| 46:37 | will encounter an attractant and then as level of contracted increase more runs will |
|
| 46:44 | . So we have more straight line into the attractant because presumably attractant is |
|
| 46:49 | nutrient likely that it can use and course it will want to use that |
|
| 46:53 | continue to go into that pool of and use it. So that's kind |
|
| 46:59 | the strategy behind this phenomenon is it's by the presence of attractants which will |
|
| 47:05 | the proportions of runs to tumbles. , And so as mentioned there, |
|
| 47:14 | it's what the motion is, what call a random walk. Right, |
|
| 47:19 | the company frequency is quite high here the logic here is to um that |
|
| 47:25 | this crazy back and forth, up down motion, it will run in |
|
| 47:29 | will detect some kind of attractant and will then force it into a biased |
|
| 47:36 | walk, such as that. so the frequency of tumbling has |
|
| 47:42 | the amount of runs has increased. , so that's what would happen if |
|
| 47:47 | sensing the presence of attractive, because wants to use that molecule. Now |
|
| 47:52 | say that you can also have repellents the repellent will actually create the opposite |
|
| 47:57 | . So it'll it'll do the opposite or so so that the soul can |
|
| 48:03 | the offending molecules. Okay, but , for chemo attractant, this is |
|
| 48:08 | it works. And so we can that uh let's look at this, |
|
| 48:16 | our animation and here it is a sell and we see that one's initially |
|
| 48:32 | a run counterclockwise rotations and that cell tumbles. So clockwise rotation and so |
|
| 48:42 | of it's on a random walk, ? Trying to hopefully run into some |
|
| 48:46 | molecules. It's actually a photo micrografx preparation. And so here is our |
|
| 48:55 | . So it can be receptors on cell surface that will bind and then |
|
| 49:01 | the levels the proportions of runs to . So there you see the receptors |
|
| 49:08 | influence the rotation of the flu And so the idea is something decreases |
|
| 49:15 | we're going toward attractive and sensing it increasing the level of runs. So |
|
| 49:22 | net movement is going toward the Okay so uh so that sums up |
|
| 49:30 | motility then. Okay so that then up this part too. So I |
|
| 49:38 | gone really over uh mostly internal structures the subtle skeletal elements, the nuclei |
|
| 49:44 | uh don't forget the party zone formation there um then prepare cell division and |
|
| 49:51 | of D. N. A. polar aging phenomenon expectation that occurs during |
|
| 49:57 | division. Uh then the very specialized uh Granules, inclusions etcetera um and |
|
| 50:05 | finding the flagellum for motility. So you're looking through the especially to the |
|
| 50:09 | structures and inclusion, the Granules Trying to try to think about what |
|
| 50:16 | some commonalities between these structures. What's ? All right, nutritionally nutritionally, |
|
| 50:22 | might you find in a photo audit , for example, what would be |
|
| 50:27 | to motion for example? So a of these structures are have some kind |
|
| 50:33 | commonality to them so it's helpful to about that as well. Okay, |
|
| 50:39 | that concludes part two folks. Next will be Chapter four which I'm trying |
|
| 50:46 | call is going to start with beyond growth and that that too, is |
|
| 50:51 | to be in two parts. Alright, folks. Thank you. |
|
| 50:55 | you next |
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