| 00:01 | Okay so here we're going to close the end of Chapter one with a |
|
| 00:06 | of topics um concluding what we started last at the end last time |
|
| 00:12 | ecology uh then about endo symbiosis and origins. So um so recall that |
|
| 00:27 | mentioned Winograd ski in the context of microbiology um samples from wetland environments that |
|
| 00:37 | discovered um these odd metabolic activities uh to this time really what was known |
|
| 00:46 | terms of nutritionally let's say among among is uh we called hypertrophic activity uh |
|
| 00:55 | of organic materials as the raw as energy and carbon source. Uh Just |
|
| 01:01 | we do as humans do and in process giving up C. 02 and |
|
| 01:06 | oxygen. So this was the metabolism was known biological metabolism. And so |
|
| 01:12 | he found these other unusual types uh which in experiments he saw that inorganic |
|
| 01:20 | like hydrogen ammonium uh were um when disappeared and converted into end products. |
|
| 01:31 | the thought was well what's doing Is this is this an actual biological |
|
| 01:35 | or visit a biotic process occurring in soil somehow. And he devised some |
|
| 01:44 | experiments to basically looking at soil that sterilized was non sterilized. The sterilization |
|
| 01:50 | course would kill any kind of living into the soil and then examine if |
|
| 01:55 | still had the capability of converting these materials. Uh And he discovered that |
|
| 02:01 | when the soil was not sterilized that occurred. So this was a clue |
|
| 02:06 | there was something biological that was carrying out and subsequently using what's called enrichment |
|
| 02:13 | Enrichment culture will talk about this In four. But enrichment culture you provide |
|
| 02:19 | to to um favor the growth of types over others. Okay. And |
|
| 02:27 | can do that by manipulating the the medium components in the in your culture |
|
| 02:34 | favor their growth. And in doing he is how this is how he |
|
| 02:39 | others discovered the with a trophic Uh He's he's completely inorganic materials source |
|
| 02:46 | sources. Things like um H. S. Um ammonium ion um even |
|
| 03:01 | and other sorts inorganic sources sources so inorganic materials being used as energy. |
|
| 03:09 | And so when we look at this in context with hetero tropes and autotrophs |
|
| 03:15 | recall that these are two most basic metabolisms. Right? So the designation |
|
| 03:22 | petro for autotrophs is relates to what the carbon source being used. Then |
|
| 03:27 | can further differentiate as we'll see as go through uh into chapter four on |
|
| 03:33 | and metabolism that you have to have designations photo and chemo so photo |
|
| 03:40 | chemo autotrophs, photo hetero tropes, hete trophies relate to than the energy |
|
| 03:47 | being used. Okay so um and uh this these these range of metabolisms |
|
| 03:55 | we see among micro so bacteria archaea can be little traffic using inorganic sources |
|
| 04:05 | can be uh Of course photo oughta your little troughs are basically chemo |
|
| 04:10 | They don't photosynthesize but they do um energy from the oxidation of inorganic materials |
|
| 04:16 | they fix the 02 to get their . Uh and so as we go |
|
| 04:21 | into metabolism uh we'll see that there this very diverse metabolic types and of |
|
| 04:28 | it's this metabolic diversity that allows for chemical cycling geochemical cycling by bacteria by |
|
| 04:37 | of of the essential form elements needed all life like nitrogen sulfur phosphorus |
|
| 04:45 | These are all of course critical elements make up basically. They're your your |
|
| 04:51 | take acids, lipids, carbohydrates, . Okay. And so organisms in |
|
| 04:57 | ecosystem each have specific requirements for the of these molecules that they can |
|
| 05:04 | And so by having lots of variety metabolisms to generate these types is very |
|
| 05:10 | activity to have in these ecosystems to able to provide nutrients that that that |
|
| 05:17 | can use. And so we kind put this in the context of, |
|
| 05:21 | know, the ecosystem cycle we saw mentioned before. And so you have |
|
| 05:26 | course every system ecosystem the foundation that your producers be it plants and terrestrial |
|
| 05:35 | , allergy cyanobacteria in aquatic ecosystems, the foundation. They are the most |
|
| 05:40 | . They take light from the convert that to chemical energy. These |
|
| 05:47 | the autotrophs of course uh organic materials produce then are consumed by consumers. |
|
| 05:53 | tropes that then break these down. . And then of course consumers and |
|
| 05:57 | both will die. And that material be processed by decomposes broken down by |
|
| 06:04 | composers. And there again you're releasing know these materials that can be used |
|
| 06:09 | others. You're breaking these down to building blocks that can be utilized by |
|
| 06:13 | too produce their own materials. Okay of course microbes are going to be |
|
| 06:19 | at all levels. They're gonna be are gonna be head atrocious. And |
|
| 06:23 | course in the among the composers as . Okay um and so this is |
|
| 06:30 | to illustrate again the importance of of types of metabolisms um to provide different |
|
| 06:38 | of nitrogen. So the nitrogen triangle have bacterial types that will be able |
|
| 06:44 | take nitrogen from the atmosphere and bring into the environment. So we call |
|
| 06:49 | fixation reactions. Okay then this ammonium that are the product of the fixation |
|
| 06:57 | be used by nitro fire as we them. And that's actually your little |
|
| 07:03 | . This trophy is B. Okay right here. They can utilize these |
|
| 07:09 | materials like ammonia and convert to Others can convert nitrite tonight trade. |
|
| 07:17 | so um a process on all three fixation notification notification due to the activities |
|
| 07:28 | various bacterial species. And of course nitrogen essential nutrients um producers themselves although |
|
| 07:36 | can you know fix CO. Two converts sunlight into chemical energy. They |
|
| 07:42 | need to have these basic elements nitrogen to support their growth and and they |
|
| 07:48 | heavily on bacteria making up just nitrogen to do this. Okay. Um |
|
| 07:55 | course the bacterial types that can also an ecosystem of nitrogen uh the petrification |
|
| 08:03 | . But we'll talk more about the later in the semester. But just |
|
| 08:08 | point out that you know that that activity microbial activity is very important for |
|
| 08:13 | . Okay. And so we had question at the end in the last |
|
| 08:17 | and so it's kind of too to this. Uh we talked about these |
|
| 08:24 | previously. So uh the true statement of course is uh it's not a |
|
| 08:33 | a coax germ theory of disease that the infectious disease uh ecologically we are |
|
| 08:40 | producers. We are as humans are . Archaea, aren't you carry out |
|
| 08:45 | pro carry outs. Um Some infectious may be caused by more than one |
|
| 08:51 | pneumonia is an example of that because types, viruses, fungi and protozoa |
|
| 08:58 | can cause pneumonia but also a single in time can be responsible in some |
|
| 09:04 | for causing multiple diseases, streptococcus for . Uh streptococcus priorities can cause strep |
|
| 09:12 | . It can cause different types of infections including um uh what's called a |
|
| 09:19 | eating disease. Um can cause scarlet . So there are cases where a |
|
| 09:25 | passenger can also cause multiple diseases. with soap and sepsis falls into that |
|
| 09:33 | , vaccines work by stimulating your body produce antibodies not androgen, so none |
|
| 09:39 | these are actually true. Okay, gee is the correct answer here. |
|
| 09:45 | so micro endo symbiosis. So uh was aware of symbiotic relationships uh Endo |
|
| 09:55 | are uh just different in terms of fact that the host and um the |
|
| 10:02 | are very very intimately associated with each . So you're human microbiome, you |
|
| 10:09 | have, the symbiont is on on body in your body. Uh plant |
|
| 10:18 | in those symbiosis. These are just talked about the nitrogen cycle and nitrogen |
|
| 10:25 | . The most common form of nitrogen occurs between bacteria that have these interactions |
|
| 10:34 | specific plants. It's a very specific um Their chemical attractants that bring each |
|
| 10:40 | of these together. And so it's very orchestrated process and specific process between |
|
| 10:45 | two your plants like peanut plants, plants, alfalfa, these are plants |
|
| 10:53 | have these relationships with bacteria and are to fix nitrogen. So the plants |
|
| 10:58 | have their own nitrogen acquisition system. you will uh in and having these |
|
| 11:04 | with bacteria, ruminants like cattle and and goats and the like uh they |
|
| 11:11 | these complex digestive compartments containing different types bacteria that are responsible for basically converting |
|
| 11:20 | grass and rain that they the animals into usable. A similar herbal nutrients |
|
| 11:29 | the cattle can then or whatever the is can then assimilate and grow |
|
| 11:34 | Okay um and so in the end symbiosis vein, this is where the |
|
| 11:44 | of how it's evolved uh through endo symbiosis with a with a bacterial type |
|
| 11:55 | capable of inspiring or photo synthesizing but giving rise to the different eukaryotic cell |
|
| 12:06 | . So uh this theory proposes that would've been a pre eukaryotic cell that |
|
| 12:15 | have engulfed let's say a bacterial type inspires um and thereby becoming the forerunner |
|
| 12:24 | the mitochondria. Okay. And so of course the mitochondria is you know |
|
| 12:31 | the powerhouses in the eukaryotic cell. enables it to break down or getting |
|
| 12:38 | to get energy um produce a P. S. Uh So a |
|
| 12:44 | then with these these mitochondria were given to the animal life of the animal |
|
| 12:51 | and the fungi kingdoms. Uh subsequently that same cell then engulfing a santa |
|
| 13:01 | type which is a photosynthetic bacterium would been a forerunner for the chloroplast. |
|
| 13:08 | giving rise down of course to plant . Okay and so again all these |
|
| 13:14 | to indo symbiosis with a specific bacterial type. Okay. Um man there's |
|
| 13:22 | strong evidence for this. So if look here at the the evidence that |
|
| 13:29 | each of these organelles the chloroplast and mitochondria do contain D. N. |
|
| 13:34 | . Um And the that DNA does genes that code for some of the |
|
| 13:41 | of those processes in those organelles. for all the processes some are still |
|
| 13:47 | the larger chromosomes for that. But uh uh some of the genes in |
|
| 13:53 | D. N. A. Transcribed and translated within those organelles because |
|
| 13:57 | do contain ribosomes and T. RNA do produce the proteins needed for the |
|
| 14:04 | of for the synthesis or black calls cell respiration that occurs in mitochondria. |
|
| 14:12 | Further the the organelles can also of during the eukaryotic cell undergoes mitosis or |
|
| 14:20 | . Those organelles do duplicate themselves prior cell division. So um so all |
|
| 14:26 | this is evidence that that these at time or once cells independent of the |
|
| 14:32 | cell. Um and histology of the . N. A. In those |
|
| 14:37 | to bacteria is known. And there um our bacterial types that relate directly |
|
| 14:44 | the D. N. A. are in those organelles. So all |
|
| 14:47 | is very strong compelling evidence that this is likely how this happened eukaryotic cells |
|
| 14:53 | about um two billion years ago. and so this is just this is |
|
| 15:00 | something you need to memorize but I want to put it in here for |
|
| 15:03 | uh timeline of life. So you the origin of earth is quite long |
|
| 15:10 | over four billion years ago. Humans in in with respect to this are |
|
| 15:16 | of course a very tiny very tiny of this scale. We've been around |
|
| 15:22 | six million years. We involved from the most recent ancestor. But of |
|
| 15:29 | the point here is precarious have been the longest. Okay evolved first. |
|
| 15:34 | Then that group of cyanobacteria are photosynthetic that evolved later. But they're the |
|
| 15:40 | that put oxygen into earth atmosphere Then you can have the evolution of |
|
| 15:46 | oxygen using metabolism. Okay. Giving of course the eukaryotes, microbes and |
|
| 15:53 | multi stereotypes. So of course, to the the prior to the formation |
|
| 16:02 | oxygen. And of course it took time for the option to accumulate. |
|
| 16:06 | still talking about an anaerobic world. . For a long time. So |
|
| 16:13 | course from anaerobic means no oxygen. life evolving an anaerobic environment. An |
|
| 16:20 | that's quite quite hostile with. Um a volcanic activity and the like. |
|
| 16:28 | so the question is that what kind life would evolve? And so of |
|
| 16:35 | it was would have been precarious. is micro fossil evidence that shows of |
|
| 16:40 | secular life uh existing three plus three billion years ago. Um Also evidence |
|
| 16:49 | evidence in the form of hope, , annoyed or molecules analogous to cholesterol |
|
| 16:55 | in our membranes. And so bacteria these in their membranes and similar but |
|
| 17:00 | similar function. And so that too evidence. You can see uh micro |
|
| 17:06 | evidence and how those morphology is look similar to what you see in modern |
|
| 17:11 | types. Okay. Um and so terms of metabolism and uh how would |
|
| 17:19 | produced energy to survive. Uh Well would have been they would have had |
|
| 17:24 | rely on of course the the materials to them to grow on. So |
|
| 17:30 | this very hostile environment billions of years would have been of course um a |
|
| 17:40 | anaerobic environment. It would have had volcanic eruptions spewing forth things like hydrogen |
|
| 17:46 | . 02 ammonia iron. Um So kind of reduced compounds in the early |
|
| 17:52 | earth environment would be the substrates uh be used for energy. And of |
|
| 17:59 | there's presidents for this year's. We're of little trolls right with bacteria. |
|
| 18:03 | just talked about can use these inorganic . So um something that we'll talk |
|
| 18:09 | in the next unit of course is and how energy sources are used. |
|
| 18:14 | so recall, you know, the transport chain, right? You've gone |
|
| 18:20 | um a mitochondrial work and the process black causes and cell respiration. Several |
|
| 18:26 | electron transport chain to which um a a source molecule is oxidized to provide |
|
| 18:34 | defeated. Okay. And a terminal er that will receive those electrons and |
|
| 18:41 | reduced in the process. Right? these reduced compounds in this kind of |
|
| 18:49 | be the electron source. And so could use things an anaerobic environment that |
|
| 18:55 | have been occurring in early earth could things like nitrate. Um so |
|
| 19:06 | So the kind of molecules you you see in this early environment and this |
|
| 19:11 | be used to re spire with. remember that we use oxygen as our |
|
| 19:17 | sector. But those that are anaerobic use molecules other than oxygen. So |
|
| 19:21 | can be a completely anaerobic environment and an organic Energy sources. But of |
|
| 19:29 | you have to be fixing c. . 2. Okay. To provide |
|
| 19:35 | carbon. Always remember, life on planet is carbon based. So you |
|
| 19:40 | to have a source for that. this would have been C. 02 |
|
| 19:43 | these kinds of chemo autotrophs. so you know, it's the kind |
|
| 19:48 | metabolism that you know if if there life on mars there's likely some kind |
|
| 19:53 | metabolism we'd be looking for and why we will be looking for precarious on |
|
| 19:58 | planet. Um So but you to historically there's there's duplications of early |
|
| 20:05 | environment have shown uh that biological compounds be produced. So things like you |
|
| 20:13 | , acids and nucleotides can be formed these in experiments involving these, duplicating |
|
| 20:20 | earth environments. So um so compelling . Um and of course having talked |
|
| 20:28 | spontaneous generation, we are talking here life coming forth from, you |
|
| 20:33 | the chemical constituents available at the And so instead of using the word |
|
| 20:39 | generation, scientists have coined the term oasis as a term to describe this |
|
| 20:51 | of these, a biological chemical chemicals together to to produce life. So |
|
| 20:59 | any case the origins of life obviously with the precarious and then evolved from |
|
| 21:05 | . So uh so then that closes chapter one and so at the beginning |
|
| 21:10 | of chapter three, chapter three of we're looking at pro cario so the |
|
| 21:17 | and function. So we're gonna focus the the inner workings of the pro |
|
| 21:25 | sell uh textbook kind of takes the of let's start with kind of what's |
|
| 21:31 | the outside then go inwards. And we really begin the journey here with |
|
| 21:39 | I refer to as a cell Right? So obviously a cell any |
|
| 21:45 | , we're gonna have a number of constituents, things like ribosomes, proteins |
|
| 21:50 | with D. N. A. or in the primaries. So these |
|
| 21:54 | certainly common uh constituents of many cells I want to focus first on the |
|
| 22:00 | . Okay so the envelope because bacteria archaea can vary with what's beyond the |
|
| 22:10 | membrane. We refer to it as envelope. Okay so there can be |
|
| 22:15 | different types of chemical structures that can a cell wall. There there may |
|
| 22:18 | additional membrane may be present. So just depends on the bacterial or keel |
|
| 22:24 | , what's there. So we refer that collectively as the cell envelope. |
|
| 22:28 | so again every cell has a boundary defines it as a cell. That's |
|
| 22:35 | we call the cytoplasmic membrane sometimes called plasma membrane but that's what defines a |
|
| 22:41 | . So what we're talking about is beyond that inner membrane if you will |
|
| 22:47 | that psychopathic membrane, that's what we the cell envelope. Um And so |
|
| 22:53 | you wanna be able to do, know, as you go to this |
|
| 22:55 | part which basically focuses on um the . So really the cell envelope structure |
|
| 23:03 | what's going on there. Okay. um so we'll go through cell membranes |
|
| 23:09 | in gradients uh the nature of the . So gram negative, gram |
|
| 23:14 | The variations of that. Not every all bacteria fall into either being gram |
|
| 23:19 | , gram positive. There are variations that. Okay. And then external |
|
| 23:23 | , capital slime layer and biofilm. . So uh so well the second |
|
| 23:31 | of this uh video lecture will start this question here which is procure itself |
|
| 23:38 | which is false. Okay, so end it here and then the next |
|
| 23:45 | electoral pickup at this point. Thank |
|
