hello everyone This video will cover chapter 1 Uh this uh PowerPoint can be found in the course content section So please make sure that uh you follow along with the PowerPoint as well Take your notes along with this Um this will uh hopefully uh help you understand the content Keep in mind um that test questions are taken from the PowerPoints So you want to make sure that uh you are studying from the PowerPoint you understand this content you don't have to worry about frantically writing down the extra things that I say as I go through this I just say the extra things to hope um hopefully help you understand the material better and give you ways to apply it So uh so let's move right along and introduce our first chapter here Um we begin with our study of microbiology with the history uh behind this science Um we see here that um Robert Hook was uh is credited for observing microorganisms the common bread mold um back in 1665 using a microscope And so that's going to be uh the basis of our study of microbiology is we're going to be describing uh uh microbes and microorganisms things that are too small to be seen with the naked eye Uh so uh this early uh discovery that uh bread mold uh consisted of um these small cells that could be observed with the microscope Uh it starts the ball rolling toward uh many of the um you know studies that followed that eventually developed this science Um what we see shortly after is we have uh Vanlowanoke observing the um uh same microbes microorganisms um we're saying most likely bacteria at the time um and uh he gave them the term here molecules Um the significance of this term is the recognition that the individual bacterial cells um were actually um living organisms that were independent organisms as if they were all each cell was its own animal So we're combining animal with molecule to say basically like a microscopic you know teenytiny animal In other words the bacterial cells uh were individually microscopically uh living organisms Um so we see uh Vanlonuk's drawings here and as we study microbiology we'll see that uh sure enough he was he was definitely observing uh bacterial cells based upon the the shapes of these cells These are exactly what we're going to see uh in the upcoming lectures So the next thing to consider as we look at the history of microbiology is um people's understanding of where microorganisms came from We see two competing hypotheses The first hypothesis was spontaneous generation Uh we're going to explain that this was incorrect Okay this was a thought that turned out to be wrong The belief here was that organisms arise from non-living material So the idea would be um I can take let's say milk and just have it um sit around long enough that all of a sudden within the milk life will spring out of it Uh bacteria will spring out of it And that's why milk spoils is um cells just suddenly appear in that milk Um but that's not the case Um if we go back to cell theory that we learned in anatomy and physiology um cells come from pre-existing cells In other words uh um all life is created by existing life So that is our second hypothesis here Biogenesis organisms arise from pre-existing organisms That milk that spoils in the refrigerator spoils because it already has bacteria in it It just didn't have enough bacteria to make it go bad yet It needed more time for the bacteria that were already there to multiply So biogenesis is the correct hypothesis Um and and um basically this is going to relate to one of our topics throughout the course that's going to be aseptic technique Uh understanding that um if we want to make sure that um the materials that we use in a lab setting or in health care we want to make sure those materials are um uh safe to use and that they're not contaminated uh in a way that would um affect their use Um then we need to uh make sure that the pre-existing organisms aren't on these things So for example um you know your hands are covered with microorganisms So it's not safe for you to touch things with your hands If you want to avoid contaminating them you have to cover them with sterile gloves Okay So continuing our history here Um the next question um that uh needed to be answered was um you know well okay what what is the proof that um spontaneous generation doesn't occur and that biogenesis is the actual uh path toward creating organisms So we have Louis Pastor um refuting or disproving the hypothesis of spontaneous generation um through the experiment that involved a swan necked flask Swan neck flask we see uh shown here in the swan neck flask uh we have a broth that if it was left out on a lab bench would eventually um be become cloudy with bacterial growth Okay We boiled the broth inside of this piece of glassear And the piece of glassware we see having the um unique neck shape to it Um this swan neck allows for air molecules in the air to reach this broth that has been sterilized by boiling So the broth has no microorganisms in it and it has air reaching it So that broth that's sitting out on the lab bench in an open flask that becomes cloudy with bacterial growth if uh if spontaneous generation was the source of the bacteria then that would mean that air plus broth gives you bacteria But this glasswware prevents any microorganisms that are in the air from reaching the broth They settle out in the lower part of the neck So what we have now is sterile air with sterile broth we see after years remains sterile Okay no bacterial growth no spontaneous generation to prove that it wasn't a problem with the broth or the air Uh we see that if you tilt the swan neck flask allowing whatever sediment has uh uh you know been collected here to mix with the broth then within a few hours the broth is overgrown with bacteria showing that it was bacteria in the air that has been growing in the broth samples um leading up to this experiment So this proved that um sterile air and sterile broth um does not result in the production of microorganisms Therefore uh disproving spontaneous generation and instead proving biogenesis proving that we need um pre-existing organisms in order to create the um uh bacterial contamination that we saw in the broth or bacterial contamination we see growing anywhere in our world So what you want to understand from the swan neck flask make sure you get this point How this worked The way this worked is it uh it allowed air to reach the broth but removed any microorganisms from the air Okay that is what made this piece of glasswware so special Now continuing with the history uh John Tindle came along and basically tried to reproduce Pastor's experiment This is part of science Um you you go and you try to reproduce experiments to confirm that the results are correct And instead of using just the regular broth that we see here that was sterilized with um the boiling process um the source of nutrients in the broth that Tindle used was hay And so hay is um you know taken from um you know the the um you know fields where it's in contact with the ground and it's picking up the microorganisms that are in the soil So the boiling process was supposed to kill off those microorganisms Um but what Tindle found was um after boiling it and giving it a chance to settle um the the broth would still end up contaminated Um so either this was proof that pasteur was wrong and that spontaneous generation was really occurring or what title ended up figuring out through further investigation There is a microorganism that does not get killed by the boiling and that microorganism uh was determined to be what's called an endospore An endospore is a dormant version of a bacterial cell This dormant bacterial cell is not harmed by the boiling process It doesn't have the cytoplasm and the internal proteins and DNA that are damaged by the boiling process And instead what actually happens is the boiling becomes a trigger to break the endospore open and cause it to become the actively growing bacterial cell that we call a vegetative cell So the vegetative cell is what we see growing in the broth making this cloudy The vegetative cells that were already in the broth when it was first created were killed by the boiling process Boiling kills the growing cells but boiling does not kill the dormant endospores that are created And the dormant endospores allow for the uh bacterial species that make them uh to survive in environments that have poor nutrients um or very extreme conditions Um endospores are found everywhere So uh across all your surfaces your tabletop right now has no nutrients It has no water It has no nutrients It has nothing for a vegetative cell to survive on And it doesn't matter because endospores are dormant They don't care if there is uh nothing for them to use for growth They can just wait until they're in the right environment Now your uh tabletop um you know you um you end up spilling some juice on it and you wipe up the juice with a napkin and now that napkin has moisture and nutrients and endospores You have all those mixed together and you put that um you know napkin in in a space that allows it to stay moist What would happen is we would see growth of bacteria because um the bacteria were now put into an environment with the nutrients and the water they needed to grow Um but the endospore allows for bacteria to uh populate areas and basically wait until the environment is ideal So one more time um Tindle's experiment discovered the existence of endospores because he discovered that there were cells that were not killed by the boiling process that was used to initially in uh pasteur experiments to sterilize uh the broth Okay And we'll learn about several organisms that make endospores And we'll be able to explain why those endospores are so important um a little later on in uh in the upcoming chapter uh chapter 3 Now at this point um these um early scientists just knew that bacteria were around and that they grew in things but they didn't realize yet that um bacteria could cause disease That microorganisms bacteria fungus viruses that these things could cause disease Okay So in order to explain that we want to define two terms more clearly The first term is infection Infection is the growth of an organism inside of another organism with or without the production of disease Okay So in AM uh in AMP we learned that uh within your colon you have um over 400 species of microorganisms that are surviving in there and that they were helpful They kept you alive They protected you from uh acquiring uh the disease-causing infections Um these are examples of infections They are uh organisms growing inside of you That is an infection without disease An infection without disease Um so the term disease disease is tissue damage or alteration of function In other words symptoms something going wrong with the body Okay so disease can exist without infection Take for example a heart attack A heart attack doesn't involve an infection Um diabetes would be a disease that's not involving an infection So disease is symptoms Infection is growth of an microorganism within the body But what wasn't connected yet was that the infection could cause disease that the growth of let's say a bacteria in your intestines could cause you to vomit and have diarrhea So we needed to build this connection to show that the microorganisms can actually harm the body potentially And that's where uh coach comes in with these postulates that show that a microbe can cause disease Okay So in order to show that a microbe can cause disease we have to go through these four steps that are shown on the next slide that prove that the microbe causes the disease Okay First we see that the microbe or microorganism must be present in every case of the disease If I'm going to say for example that the HIV virus causes AIDS I can't have an example of somebody who has AIDS who does not have the HIV virus in their body I have to show that in every case of the disease that uh particular microbe is present Next we have to be able to isolate that microbe We have to be able to grow that microbe as a pure culture So I need to be able to take whatever it is that I think is causing a disease and isolate it and then give it to a susceptible host In an experiment I have to give it to a susceptible host and see that that uh microbe does in fact cause the disease to develop in that healthy new host Okay So looking at that we suspect here that this bacteria causes pneumonia We see that uh this mouse that died from pneumonia had this bacteria in its respiratory tract We take that bacteria We grow it in pure culture So the only thing growing on this petri dish is this bacteria We give this bacteria to a healthy mouse We see that the healthy mouse develops the same pneumonia that the healthy mouse uh not only gets the disease of the pneumonia but in addition that we are able to find that same bacteria and prove that that bacteria was present in this second diseased mouse This is how we can prove that a microbe causes a disease Okay So let's take for example something more recent uh you know what with covid-19 uh you know we had to figure out like well okay well is this particular virus causing these particular symptoms uh you know we need to isolate the virus from a diseased individual u isolate it and then see what happens if it is introduced into a healthy individual and show that it is the introduction of that new virus that causes the um symptoms that we were observing So now that I introduced CO 19 what are the limitations of koshas postulates in particular what I really want you to think about and answer please make sure you're paying attention to this What are the limitations of koshas postulates when it comes to the human model okay Is it okay for us to take a uh disease-causing uh microbe and give it to a lab rat uh yeah that there there are some ethical concerns to this certainly Um but if if it's for the greater good um then this is what research relies upon is animal models um that are going to be subjected to uh in infections and the resulting diseases Um but when it comes to the human model is it okay for me to take a virus like let's say CO 19 and say I I found this in a sick patient and I'm wondering if this is what's causing this this outbreak right now Take that virus and give it to a healthy person That's what we would need to do to use Kos postulates in a human model But the answer is no You cannot do this This is unethical Okay it is unethical to uh use uh kosh postulates on uh a human model Okay So I can't say I suspect that this new virus that I just found in the year 2027 you know uh whenever in the future I can't say um that this uh this new virus is something that I can just go and put into a healthy person to see what it does to them Okay So the limitations of of coast postulates is that we have to uh use them with animal models and we cannot use them with human models because they are would be unethical Okay Now wrapping up our first chapter Um we've used some of this terminology already and we want to clarify it The term microbe is anything that's so small that we need a microscope to see them So the one thing that all microbes share is that they cannot be seen with the naked eye Um but we have two categories we want to consider The first is living microorganisms living microorganism To be an organism means that the microbe is alive Okay So our microorganisms are the living examples Bacteria we see ari Uh we see prozzoa algae fungi and multisellular parasites All of these are living They're all made from cells Going back to our cell theory all things that are alive are made from cells So a the the right term to describe a bacterial cell prozzoa fungus the right term would be microorganism Non-living uh microbes um oops non-living microbes we see include viruses vyroids and prons um these are not cells These are simpler than cells They are much smaller than cells They are considered microbes because they are smaller than we are able to see with the naked eye Um and they are able to be replicated uh but they are not living cells and therefore they are not microorganisms they instead are microbes non-living microbes Okay Um the next point here is um understanding where microorganisms fit into our world We see here that we rely in our ecosystems on microorganisms They make nitrogen that is in our air uh they make nitrogen available for us through a process called nitrogen fixation They take the nitrogen gas from the air They turn it into molecules that can be used by plants and animals as uh the the uh source of nitrogen that plants and animals need for making proteins So uh if it were not for microorganisms plants and animals would never exist We see microorganisms produce oxygen both on land and in the water Um we rely on plants on land certainly to make oxygen but oxygen is needed in the ocean Oxygen is needed in the lakes Where is that oxygen come from uh microorganisms are everywhere and microorganisms are uh in in many cases capable of producing oxygen if they are photosynthetic microorganisms And so it's photosynthetic microorganisms that help sustain once again the other life forms the plants the animals the um the the fungi other organisms in the environment uh we see that microorganisms unlike most animals and plants are able to break down cellulose Cellulose is what plants use for making their cell wall and um we need microorganisms to digest this material or else uh every leaf that a plant created would still be here today Uh so microorganisms are are needed to help um decompose organic material in our environment We use microorganisms for food and beverage production Uh we'll see later on in in the course about how bread and beer are made through alcohol fermentation that's carried out by microorganisms uh yogurt uh and cheese are are made through uh different uh forms of fermentation as well Uh so we rely on microorganisms for food and beverage um and bioreediation We see that microorganisms are uh ultimately what we rely on for uh clearing out environmental pollutants Uh we we see the list there uh we have pesticides and um petroleum waste and radioactive waste Some of these um are are removed by the presence of microorganisms And finally we rely on microorganisms uh to um create many of the um useful materials that we uh need in our um agriculture and and uh pharmaceuticals So we see uh insecticides uh antibiotics um all these things uh we rely on microorganisms for another point about the usefulness of microorganisms is that they make uh for great models in um the uh biological research um the advantage of using bacteria as a model as opposed to for example the lab rat um you know why can't we just do all of our studies with mice and rats and things like that well um bacteria grow very rapidly So we're able to see the effect of something over generations Uh bacteria uh go through a generation of growth every few minutes So in the range of 20 minutes to an hour we're seeing a new bacterial generation So we're able to follow the effects of something over generations in a bacterial model that would have taken uh months or years to observe in an animal model They're also inexpensive to grow It's a lot easier to provide uh bacteria with the nutrients that they need for growth than it is to uh you know feed and house u the animals for research Um that being said um you know I mean it's it's not always great for the animals out there but uh but yeah anything we can do to make the life of an animal better is is better for science Um um so now uh we're going to look at categories of microorganisms Um microorganisms are all made from cells Um but the question is what type of cell we see that there are going to be two cell types The proariote which means pre-ucleus This is a cell that does not have its DNA surrounded by the lipid uh membrane the envelope that we saw in when we studied the cell in A and P Um the DNA is freely floating around in the cytoplasm It does not have the membrane around it Um whereas the ukareote is going to be uh any cell that has the true nucleus and with that we'll also see u many different membranebound organels as well So things like the endopplasmic reticulum and Golg apparatus um these uh other internal membranes in addition to the um nuclear envelope So here's our proarotic cell with the example of a bacteria Uh we see the DNA freely floating around inside the cytoplasm whereas the DNA in a ukareotic cell is inside of this membranebound nuclear envelope We do not see any other membranebound organels here We don't see endopplasmic reticulum Golgi apparatus mitochondria All those things are missing from the proarotic cell but are present in the ukareotic cell Now another um consideration when we are categorizing microorganisms is u what domain we uh place them in They're going to be three domains We see the bacteria the ari and ukaria Uh the first two domains the bacteria and ari are both proarotic So this might seem weird at first when we're saying that the really really simple cell the bacterial cell right here we're considering two of the three domains of life Two of the three categories of life are representing this type of cell where only onethird represents this type of cell The ukarotic cell that we find in animals plants algae fungi prozzoa all those things that you think of are ukareotic and yet they only make up one domain And that's because the bacteria and ari are the oldest cell types These have been around a lot longer than ukareotic cells So um so since they've been around longer there's there are more of them and therefore they get their own category their own domain So the bacterial domain we see bacteria are single-sellled proarotes but what it really defines bacterial cells um is the uh production of this protein here pepidoglycan We'll use peptooglycan several times throughout this course So do yourself a favor and immediately build that connection that bacteria make pepidoglycan Okay And we see bacteria are found in all environments Uh bacteria all over the world The archa are another um ukare I'm sorry proarotic cell type Um we see single cell proarotes Um they do not make the pepidoglycan that we saw with bacteria And one thing that uh is really unique about this domain is that it includes uh some organisms that live in very extreme environments Uh so we see the examples of uh the Dead Sea and Great Salt Lake They live in environments that are extremely salty Um they live uh next to underwater volcanoes in boiling water These organisms um are are unique in their capacity to exist um in some of those areas within this earth that we would never have expected to find life And we'll revisit later on in the course um the importance of these organisms living in boiling temperatures Now the ukarotes um they are less extreme uh organisms we tend to find um them in uh conditions that we would expect to find life not not in some of these extreme situations Um we saw that the cell is much more complex and is generally larger So we see them um coming in at a size uh anywhere between 25 to 50 times larger than a bacterial cell Um so what that means is that when we're doing a study of these organisms with microscopes um we're able to see many more details of a ukareotic cell when compared to a proarotic cell These are you know 125th the size They're much much smaller There's much less to see with a conventional microscope And we see the um life forms that fit in this category of the ukarotes with the algae the fungi and the prozzoa are all um uh categories of organisms that have u microorganism examples within the ukarotes So we don't see plants and animals included in this even though plants and animals are ukarotes because we don't have the microorganism form of a plant or animal Uh this course will rely heavily on naming many of the uh microorganisms and so they'll follow this common nomenclature Uh so the naming process uh the uh organisms that we'll learn about will have a genus that is the capitalized name followed by the species that is not capitalized They're both italicized So when we write them out we see them in italics The capital genus the lowercase species So E.coli coli is short for assertia Coli um the genus followed by the species So we're going to learn about many many organisms and each one we'll start off with the genus So we'll say basillus and then the species and fraus uh strepus uh pioyny So we're going to um start with the genus and then the species And the significance of the genus is that um this will be used to show relatedness Uh so for example we will learn about um four different species that all have the same genus claustrdium That means that claustrdium tetany claustrdium bodily clust claustrdium perfingens and claustrdium difficil These four organisms are all different species but they're all from the same genus which means that they are very closely related And you're going to be able to use that to help learn about these organisms because if you learn about something from uh from the same genus then you can oftentimes apply that information to something else within the same genus We mentioned that there are the non-living microbes the viruses vyroids and prons We'll have a whole chapter on uh these that we'll get into Viruses once again are simpler than um the microorganisms They are not made from cells They do contain nucleic acid so the DNA or RNA and a protein coat but they don't have the um the overall structure of a cell Um we do see that viruses are also unable to replicate themselves They need a host cell to replicate them So it's one of the reasons why we do not consider them to be alive is that they can't grow on their own They need a cell to grow them to replicate them And for every living organism uh there is a virus that is capable of infecting it So viruses are very prevalent and capable of infecting all life forms as we know it The vyroids um simpler than the viruses We see that they are just a single piece of RNA They don't have the protein coat And um as we understand them right now vyroids infect plants They appear to only infect plants Um but there's much more to learn about vyroids um as as future research is done And finally the prons These are abnormal proteins Um a pron by itself is actually a protein that is found in your central nervous system Um but uh pron diseases are caused by um abnormal prons So proteins that you would normally have in your uh central nervous system but are uh mutated are they don't take on the normal form and therefore cause disease in animals Okay So just a brief comment about each one of those but we'll learn more about them going forward in the class Um so we we got a lot to tackle in this course Uh I hope you guys are feeling up to it and um uh please uh if you have any questions about this content along the way don't hesitate to reach out to me so I can help you understand it to your uh very best ability um so you're successful with uh this lecture material