Hey everyone, Dr. D here. Thank you for joining me for this lecture series for microbiology for non-science majors. We're covering Talaro's foundations in microbiology 12th edition. Uh this is by Barry Chess. So if you're using this textbook, that's awesome. We're going to be covering specific chapters from this textbook. Uh so let's go ahead and get started. Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D. Explain stuff. Again, welcome to the course. This is going to be a lecture series for biology 2420, biology for non-science majors. Uh, I'm Dr. D and I'll be joined by my two cats, Gizmo and Wicket. Uh, Gizmo is mischievous and loves adventure. Uh, Wicket is motivated by food. We recently had a uh Etsy artist draw them and they're hanging right behind me. Gizmo is the cat at the bottom of this picture right here where my finger is. And Wicket is doing his little peekaboo on the side. And you can distinguish the two by Wicket having the you know spot on his nose. All right, let's go ahead and get started with chapter 1 covering the main themes of microbiology. Let's get started. Now, to start, let's define what microbiology is. What are you here to study? What is microbiology? Well, simply put, microbiology is the study of organisms or small infectious agents that are too small to be seen without magnification. And I just want to quickly define the difference between an organism and a small infectious agent. Organisms are alive. You should know that when you refer to an organism, you're referring to a living creature. And in order to be an organism, you must be uh at least one cell big. You need to be in one of the three domains of life. Do you guys remember the three domains of life? We're going to review this, but many of you may have learned this in biology in high school or in biology 1406, you know, biog. And that is that the three domains of life are bacteria, archa, and ukaria. Those are the three domains of life. And organisms are they they fall under one of those three domains of life. So if you don't belong to one of those three domains of life, you're not technically alive. And in that case, if you're small and you can cause disease, but you're not a cell, you are classified as a small infectious agent. Okay? So for instance, small infeious agents include viruses. Did you know that viruses are not alive? Did you know that viruses are not made up of cells? They don't belong to any of the three domains of life, right? And prons as well. These prons are simply made up of protein. So when you hear about viruses or you hear about prons, you should know that these are not alive, but they can cause disease and they are small. That's why we study them. In fact, anything that's small that causes disease, right, that could be spread amongst people or animals, right? These are these are classified as germs. And these are classified as things that are studied by microbiologists. Now what are some actual microorganisms? We have bacteria. We have archa. We have fungi. We have prozzoa. We have algae. And we also have helmmes. Did you know that helm refers to worms? And I know what you're thinking. You're thinking worms aren't microorganisms. Worms are pretty large, right? But microbiologists still study them because of so many different worm diseases that people can get. These are parasitic diseases you can get. Right? And by the way, did you know that usually when you get a worm disease, it's not because the adult worm entered your body. It's usually because the microscopic eggs entered your body or the cysts entered your body. Right? So usually um we do study worms as microbiologists and that's because it's the eggs and the cysts and the microscopic part of the life cycle of the worm that infects the person. So anyway, you're here to study all these little organisms and infectious agents because they can cause disease because they can spread from person to person because you're going into healthcare, right? If you're in this course, you're most likely going to become a nurse or go into uh dental hygiene or something of the sort in health care. And so you should understand germ theory. You should understand how germs spread around. And this is exactly what you're here to learn about these organisms and infectious agents. In fact, let's do a sampling of fields and occupations in microbiology. Starting with medical microbiology, public health microbiology, epidemiology. All of these are areas of microbiology related to public health and spread of disease. Medical microbiology studies the effects of microorganisms on human beings while public health and epidemiologists monitor and control the spread of diseases in communities. Think of the US Public Health Service, the Centers for Disease Control, right? And even the WH, the World Health Organization that monitor the spread of disease. We also utilize microbiology for biotechnology, genetic engineering, and industrial microbiology. All three of these areas uh revolve around the idea that microorganisms can be used to derive desired products. We use them in order to make medicines or in order to make solvents or chemicals or various alcohols that we need in industry. Immunology. Did you know that immunology is the study of your immune system? And your immune system is there in order to fight off these various microorganisms and small infectious agents. So by understanding the relationship between these invading microbes and your immune system, we can better understand how to fight off disease. Agricultural microbiology. This is the branch concerned with the relationships between microbes and domesticated plants and animals. By understanding how microbes work in the ecosystem and on the farm, we can better understand how to make better crops. We can have healthier animals and how to grow those crops and animals better as well. Food microbiologists, these are scientists concerned with the in impact of microbes on the food supply. We're looking at areas such as food spoilage, food born diseases, and production. Right. So imagine monitoring uh foods for EC coli or lististeria or trying to understand how to prevent these canned foods from becoming spoiled. Okay. And that's just a taste of the different areas that work or revolve around microbiology. But you as a nurse or a dental hygienist, you're going to be encountering these germs as well right in in the clinical setting. And so you by understanding how they work, you're going to keep yourself and your patients safer. So let's carry on with the origins of microorganisms. Bacteria like microorganisms have existed on earth for about 3.5 billion years. We started with having procaryiots which are these pre-nucleus organisms. These simple cells that lack a nucleus. That's the definition of a procariat. A procariat is a organism that lacks a true nucleus and lacks membranebound organels. Ukariats on the other hand came later and ukareots have a true nucleus and they have membranebound organels as well. And I just want to make one more point. Um you guys have probably learned the difference between procariots and ukareots before but just to make a point um the main membranebound organel is the nucleus. So yes the nucleus itself is a membranebound organal. And do you guys remember what organels are? Can you beat Wicket? Let's see. Wicket's going to help out now. Can you beat Wicket? What is an organel? That's right. Wicket. Wicket always chimes in with the right answer. I've only been I've only seen him be wrong twice before, but yes, Wicket said uh that that organels are functional parts of the cell. So just like your body has organs, right? You have the heart, the liver, the brain, and these are all functional parts of you, you also have functional parts of the cell. So the nucleus is an organel. The chloroplasts are organels. The mitochondri are organels, right? All of these are organels. Different functional parts of the cell. And some of these parts of the cell have their own little membranes. And that's what they mean by a membranebound organel. That's what we that's all we mean. Some organels have membranes like the nucleus. Some me some organels don't have a membrane like ribosomes. So ukareiots have membranebound organels including the main one which is the nucleus right proariots on the other hand they also have organels but they don't have membranebound organels and they don't have a nucleus. Do you know what a nucleus means? It means that your genome your DNA is inside of a double membrane. Right? That's what a nucleus is. That's a true nucleus. Proariots don't have a true nucleus. They still have DNA, right? They have DNA, but that DNA is just floating around in the cell. It doesn't have a double membrane around it. So, it's not a true nucleus. I hope that made sense. Hopefully, that's all a review, right? But if not, that's that's exactly the difference between proariats and ukareots. Those are the two main types of cells. So here we can see a timeline of the origins of microorganisms with the universe beginning around 14 billion years ago. The origin of life ha having uh been about 4 and a half billion years ago and the earliest proarotic cells appeared about three and a half billion years ago. And remember I said proariots appeared first and then later at about two billion years ago we have the earliest ukareotic cells uh and then uh the rest of organisms since then. So this is a rough timeline of the origins of microorganisms and do you guys remember what I said? There are two main types of cells that organisms can adopt. Right? The simplest creatures are the procaryiats and the more complex creatures are the ukareiots. The procariats are microscopic. They are unisellular. They lack a proper nucleus. So they lack nuclei and they lack membranebound organels. Ukariats are they can be unisellular or multi-ellular. They they some some are unisellular like uh have you guys ever heard of amoeba right? Have you ever heard of an amoeba? An amoeba is a unisellular ukareot. But you and I are multisellular ukareots. Right? And what does a ukareotic cell possess? That's right. It possesses a nucleus as well as membranebound organels. Okay. And by the way, hopefully you remember all the membrane bound organels, but we'll touch on those in another chapter. When I say membranebound organels, I'm referring to the main one, which is what? Can you beat Wicket? That's right, Wicket. Uh the nucleus, which is uh double membrane actually. And then there's so many other membrane bound organels that you find in ukareots, but you don't find them in proariots. So I'm talking about the mitochondrian. I'm talking about the chloroplasts. I'm talking about the rough and the smooth endopplasmic reticulum. I'm talking about the GG apparatus. I'm talking about vacules. I'm talking about all kinds of different losses and peroxomes. Right? These are all membranebound organels. These are things that only ukareots would have, not procariots. Procariats have organels that are not membrane bound like ribosomes. Next, we talked about viruses as well. Are viruses alive? Can you beat Wicket? That's right, Wicket. Viruses are not alive. They are ascellular. That means they do not possess us. They're not a cell, right? A means without. These are known as what? Remember, small infectious agents. These are not organisms. You shouldn't call a virus an organism. A virus is not alive. A virus is not dead. Instead of saying alive or dead with viruses, we say active or inactive, right? And we call them infectious agents. These are parasitic particles composed of a nucleic acid, either DNA or RNA, as well as protein surrounding that DNA and RNA. That's all they are really essentially. Here you can see the microbial structure. So on the left you can see a cartoon of a bacterial cell or a proaryotic cell and on the right you can see a cartoon of a ukareotic cell. Do you think real quick let's see let's see if you can beat wicket here. Do you think these two are drawn to scale? The proarotic cell and the ukareotic cell are drawn to scale. Do you think they're roughly the same size? That's right. Wicked. No way. Uh they these are and these pictures are the same size. But you should know something. You should know that procariats like bacteria and archa proariots are so small and simple compared to ukareots. Right? A ukareotic cell like this on the right. A ukareotic cell is huge compared to a proaryotic cell. It's about 10 to 50 times larger. Right? So a ukareotic cell is 10 to 50 times larger than a proarotic cell. Okay? So you should keep that in mind. Here they're just drawing them the same size so it's easy to look at. But in reality the proaryot the bacteria or the archa is always way way way smaller than the ukareotic cell. Here you can see actual images of a proaryotic cell. This is a proaryotic cell with whiplike fleella on uh attached to one end and here you can see a ukareotic cell with also whip-like flaga as well. Okay. But again, even though these look the same size, uh, this one's just more zoomed in. Uh, the bacterial cell is always going to be smaller than the ukareotic cell. And then a virus is even smaller than those two. Remember, viruses are not alive. They're not made of cells. In fact, all viruses are essentially is either DNA or RNA surrounded by a protein coat. So viruses are incredibly small. Viruses are way smaller than either of these proarotic cells or ukareotic cells. Viruses are even smaller than that. Okay. Here you can see some bacterial cells. These are the these are the bacterial cells of mcoacterium tuberculosis. The bacteria that causes tuberculosis the disease. It's a rodshaped cell. When I say rodshaped, I'm talking about these long cells, right? That's a long cell called a rodshaped cell. Here you can see some fungi. This is the fungi called risopus. Ropus stolonopher, which is the common bred mold. And you can see the little spore structures here. These are these are called the sparangi spores. And inside of those you'll find the little spores, the the mold spores which can spread or disseminate. Here's a here's an image of an algae. This algae is called microsteras trunata. It is a photoynthetic organism. Algae is photosynthetic. Algae can undergo photosynthesis. And by the way, this is just showing you some different sizes and shapes and types of cells. Uh, you know, we're going to go into much much more detail in subsequent chapters. This is just giving you a taste, an appreciation for the different types of cells out there. Here we can see a small infectious agent. Have you guys remember we've just lived through a pandemic uh co 19, right? And this is an image, an actual image with an electron microscope of the SARS COV2 particle. This is the virus itself. And do you guys know what corona means? What does corona mean? Can you guys beat wicket? That's right, wicket. Corona means crown, right? And look, these little viruses look like they have little crowns. See that right here? Looks like they have little crowns. And we'll learn what those crowns are. Actually, they're spike proteins. But, uh, because these viruses look like they have little crowns, they're called corona viruses. Isn't that neat? And again, would we call these living or dead? No. These are small infectious agents. They are not proarotic cells. They are not ukareotic cells. They are simply nucleic acid such as DNA or RNA surrounded by a protein coat and some other factors as well which we'll go into in the virus chapter. Here's an here's another big cell. This is a large ukareotic cell. An example of what's known as a protozoa, an animallike single cell ukareot. And this is known as oxyricha trial and it's showing you its tufts of psyia which function like tiny little legs. There's quite a diversity of different sizes, shapes, types of microorganisms out there which we're going to discuss a bunch of them uh in chapters to come. And here you can see the little worms. You can see the little uh types of helm. Remember helming stands for worms. And this particular worm is a type of round worm called tchanella sporales. And you see these little coils, these little spirals, right? This these are the coiled up worms inside of the host's tissue. Did you know that in the background this is a slice of pig tissue? Right. So, um this is like imagine if you have some pork and you make a section of the pork muscle. Uh that this is a worm that lives inside of the muscle and and this worm causes tchinolosis and you can see it here. This is why, by the way, this is why you need to cook your pork thoroughly, right? Make sure you cook pork thoroughly because it's known to harbor lots of different little parasites that can spread to you if you undercook the food. Now, let's talk about some microbial dimensions. This means how big these organisms really are. But before I start, I want to show you something here. These are organisms up here that are what's known as macroscopic. Macroscopic organisms are large enough for you to see with your naked eye. And in fact, anything that's larger than 0.2 millime is large enough to be seen with the human eye, the naked eye. So for instance, a flea, a flea, you can see a flea and a flea is about two millimeters large. Okay? Remember the round worms I told you about, tranella? Those round worms, you could see them, too. They're about 1 millimeter. Uh remember the algae I told you about? That algae was also about, you know, a little bit less than a millimeter. And it's not until you get down to a fifth of a millimeter, that means 0.2 millime. So think think of a millimeter. Uh think of one tiny millimeter, which is about, you know, how long your nail is, you know, if you're if you have short fingernails. Um think of one millimeter and then think of a fifth of that. So 0.2 two millimeters. And that's also known as, take a look here, 200 micrometers. 200 micrometers means the same thing as 0.2 millime. So make a note of that real quick in your notes. Essentially, what I'm trying to say is that 1 millimeter equals 1,000 micrometers. This should say micrometers next to it. Okay, micrometers. Uh so if if one millimeter is 1,00 micrometers, then remember 2 millimeters is 200 micrometers. And this is what the symbol for micro looks like. By the way, when you see the little U with an extra leg, that's a micro. You know that's the symbol mu for micrometer. Um so again why am I stressing this? Well it's because 200 micrometers or 0.2 millime is the resolution limit of your eye. Anything smaller than that you're not going to see. So take a look here. Remember our protozoan friend I told you about that prozzoa is about 50 micrometers. So, let me see if you could uh beat Wicket here. Do you think you could see this protozoan uh with your naked eye? That's right, Wicket. You can't see this. This is way smaller than the resolving power of your eye, right? So, you can't see organisms that are 50 micrometers. In fact, if we look at mold spores, you can't see mold spores either. They're way too small. They're 20 micrometers. Spiroites. These are some of the larger bacteria that they have a spiral shape to them. They're about 10 micrometers. Look at this rodshaped bacteria. Remember mcoacterium tuberculosis? Okay, remember the rodshaped bacterium? That's right. That's about five micrometers. You're definitely not going to see these with your naked eye. And then here are some caucus shaped bacterium. That means spherical bacterium. You're not going to see those. And then you have some of the smallest bacterium here at one micrometer, the rakettias. You're definitely not seeing that stuff. So you see what it says right here. Most bacterial cells fall between 10 micrometers and one micrometer in size. So again, can you beat Wicket? Can you see bacterial cells with the naked eye? That's right, Wicket. You're definitely not seeing bacterial cells with the naked eye. And even ukareotic cells, you typically can't see them with the naked eye unless they are really, really large ukareotic cells. Okay, so typically, okay, I want you to understand this. Okay, typically you cannot see microorganisms with the naked eye. And why is that? Well, because they are microscopic, that means they are smaller than the resolution limit of your eye, which is 200 micrometers. Right? Does that make sense? So, in general, in order to see organisms, in order to see bacteria, archa, in order to see ukaria, the cells of a ukaria, you're going to need a microscope. Because microscopes magnify the sample and they magnify it to the point where you can see it. So the the microbiologist's best friend is a microscope. Uh in fact in every microbiology lab you're going to find microscopes. It's because without microscopes you're not going to be seeing the cells and these germs that you're trying to study. Now one more thing before we move on. Did you know that a light microscope, you know, like the typical type of microscope you find in the lab, uh, a compound light microscope, you know, it only it can only magnify by about a thousand times before it really reaches its limit of magnification? Do you know what that means? That means that anything that's smaller than about one micrometer, you can't really use a light microscope to resolve it. But what about viruses? Do you guys remember are viruses bigger or smaller than cells? They are way smaller than cells, right? In fact, look, herpes virus is about 100 nanometers. A nanometer is a thousand times smaller than a micrometer, right? So, these are way way way small. These viruses, HIV virus, polio virus, herpe virus, you know, DNA molecules, you're not going to see viruses. You're not going to see viruses or or these biomolecules. You're not going to see them because they're ultra microscopic. Uh they the viruses fall between 2 and 10 nanommeters in size. So in order to see these, you know what you need? You can't use a light microscope. You need an electron microscope. So if we ever go to the lab, let's say we go to the microbiology lab and I bust out the microscopes, you know, the light microscopes, which of the three can you not study? Uh ukareotic cells, proarotic cells, or viruses? Which one would you not be able to resolve with a light microscope in the lab? Can you beat wicked? That's right. Wicked viruses. The microscopes you see in a typical microbiology lab, the light microscopes are pretty much useless for looking at viruses. You're not going to you're not going to take a microscope and look at co virus or the flu virus. You're going to need a specialized electron microscope for that. And did you know these microbes on the planet Earth are so important for energy flow through the ecosystem? Let me explain. Energy enters our planet usually by sunlight, right? The sun powers pretty much everything, all the energy on the planet. So, it's those photosynthesizers, these creatures that capture sunlight to produce sugars. They're the ones that are known as the producers. They're the ones that can capture sunlight. Then you and I which are consumers, we consume these plants and other photosynthesizers in order to grow. And then when we pass on, it's the decomposers which then recycle those dead organic materials back into the ecosystem. So it's it's this it's this flow of of of energy. The photosynthesizers being the what are known as producers. Next, the consumers which eat that eat the photosynthesizers. And then lastly, the decomposers like fungi and certain bacteria that decompose that dead organic material, bringing those nutrients back to the earth. Here you can see an algaal bloom. You can see algae and this algae is capturing that energy from the sunlight. Here you can see all different types of algaal cells. Here you can see a type of fungus, right? Fungi are good at decomposing. When you think of fungi, think of decomposers. When you think of algae, think of photosynthesizers. All right, let's do our first concept check and then we'll do our first break time with Gizmo and Wicket. Okay. Uh it's a fun little break between sections. Uh so concept check number one, which of the following does not describe a fungus? does a fun. Well, first of all, you should know that fungi are ukareotic. In fact, let me let me um let me explain something before we do this concept check. I just want to hop back to this slide over here with you. Here we go. Um and do you guys remember I want you to think back um what were the three domains of life? Can you beat Wicked? That's right. is always wicked. The three domains of life are bacteria, archa, ukaria. That's it. If you're a living thing, you belong to one of the three domains of life. Did you know that two of those two of those are proarotic and only one is ukareotic? So bacteria and archa are proariots and only the domain ukareia are ukareots. That means they're made up of ukareotic cells. So take a look here. I wanted to show you something. I told you about microorganisms, right? The bacteria are proarotic. The archa are proarotic. Now what does that make the rest of these? The fungi, the protozoa, the algae, and the helm, the worms. All four of these must be what? All four of these are ukareots. Does that make sense? So fungi are ukareotic. They fall in the domain ukareot. Prozzoa are ukareotic. Algae are ukareotic. Helmans are ukareotic. But what I want you to know is these are all made up of at least one at least one uh ukareotic cell but most of them are made up of more. Um fungi are decomposers or they could be parasites as well. Prozzoa are animallike single cell ukareots. That's what a prozzoa is. It's an animallike single cell ukareot. Think of amoeba. Algae. Algae is a photosynthetic organism and these can be single cell or multi-ell. Sometimes if they are multi-ell they are usually what are known as colonial organisms. And then lastly you have helmines which are the worms. These are multi-ellular ukareots. So again all of these are ukareots. Knowing that let's get back to this. Which of the following does not describe a fungus contains a nucleus? Well it should contain a nucleus because it's a ukareot. has 80s ribosomes. That's correct because all ukareots have 80s ribosomes. Proariats have smaller 70S ribosomes. We'll cover that in a subsequent chapter, but make a note of that. And remember I told you fungi are good for decomposition. They decompose, right? Um so what's what do they not do? They are not photosynthetic. Fungi are not photosynthetic. algae are photosynthetic. So, the answer is D. With that, let's head to our first break time with Gizmo and Wicket. See what these little guys are up to and we'll be right back for more. All right, welcome back from our break time with Gizmo and Wicket. Let's carry on with lifestyles of microorganisms. The majority of or microorganisms live a free existence. They are relatively harmless to people and in fact they can be beneficial uh to life on earth. However, some microorganisms as you are probably well aware have close associations with other organisms even being parasites. Parasites live on or in the body of another organism called the host organism and the host can become damaged. Parasites become nutritionally dependent on the host. Microbes that cause harm are called pathogens. Patho means pain and these are pain makers, right? That's kind of where that term comes from. Pathogens cause pain, cause harm. Nearly 1,500 different microbes cause human diseases, and up to 10 million deaths from infections occur per year worldwide. However, because of lack of medicine and lack of access to health care, the majority of these deaths from infections is concentrated in the developing countries. Here you can see the burden of of infectious disease in lowincome countries on the left and high inome countries on the right. Notice uh here's a kind of a a legend for us. We're looking for infectious diseases, right? In infectious diseases are in green, non-infectious are in blue, and red are just due to injuries. Notice how in lowincome countries the, you know, we have a lot of grain going on here from neonatal conditions that are due to germs to lower respiratory conditions to diarrheal, malaria, tuberculosis, HIV and AIDS. Look at this. In lowincome countries, infectious disease due to germs is uh among the top 10 leading uh causes of death. Whereas on the right, take a look at this. We only have lower respiratory infections cracking the top 10 in the high inome countries in first world countries. And this is because of better access to health care, better access to antibiotics, vaccines, etc. And all of this, all of this goes to show the importance of microbiology. Our understanding of microbiology has led to the development of these drugs, of these treatments, of these vaccines and that's what's allowed the infectious diseases to become uh not leading causes of death in in the highincome countries. In fact, microbiology has been around as a field for over 300 years now. The prominent discoveries in the field include those with that have to do with microscopy and uh the development of the microscopes. Developments in medical microbiology including germ theory. Germ theory the theory stating that diseases are caused by germs. Communicable diseases are caused by germs. and modern microbiology techniques which we use in the current lab settings today. Before microbiology, life was kind of a mystery and people actually believed that life came from non-living entities. So life can spawn from uh dead materials. This was an idea known as spontaneous generation. an early belief that some forms of life could arise from vital forces present in non-living or decomposing matter. So for instance, flies would spawn from manure. You know, the manure being non-living matter and the flies emerging from the manure, right? And this was disproven by one of the earliest microbiologists and a father of microbiology pastor uh who eventually disproved spontaneous generation and showed the theory of biogenesis the idea that living things only arise from other living things. We can thank uh Louisie Pastor for disproving spontaneous generation. And this is one of the concepts that led to the rise of cell theory as well. Cell theory stating that all cells come from preexisting cells and all living things are made up of at least one cell. Now for the development of the microscope, Anthony Vanluenhook was uh instrumental in the development of the earliest microscopes. Uh Anthony Manluenhook was a very interesting character. He was actually a habdasher which is a outfitter and a you know a dealer in fine uh fabrics and uh he was a habdasher in Holland during the 1600s. and he as a hobby would put together these microscopes. And this was his famous uh microscope setup. It's called his pinhole microscope. You can see this is a piece of copper with a hole inside of it. And inside of that hole, he placed a a lens which he fashioned. And then you have this little screw. And at the top of this little pin, this is where you place your specimen. So, all you do is you hold the the pinhole microscope here, hold it up to your eye, and look at the specimen. And there's even a little focusing screw that moves around the specimen as well. And so, this is how you would observe the specimen. You would look through the pinhole microscope, look at the tip of that needle, and view a magnified image. He uh he used it to look at thread counts on fabrics, but then he turned his attention to rainwater from a clay pot and he saw little organisms. Next, he even looked at plaque from his teeth. And what did he see? He drew some, you know, this is this is kind of a depiction similar to what Luen Hook would have described. And this shows bacterial cells from milk, you know, and other types of little microorganisms that he would spot. So these were some of the earliest depictions of microbes, right? He called them an animolcules like almost like animal molecules, I guess, is a play on that term. And uh this opened up all kinds of doors for microbiologists, early microbiologists to see a whole world that was not known to be there, right? Because without microscopes, remember you the existence of these cells, these germs was unknown, right? Because they're smaller than the 0.2 mm or 200 micrometer uh resolution limit of the eyeball. Isn't that neat? Now, these early microbiologists, they employed the scientific method in order to make their discoveries. By the way, um I'm not going to go too deep into how the scientific method works here because, you know, it should be should have been covered in the previous biology class. But if you want to review exactly how the scientific method works, I have a video that I'm going to link above right here. You can see above the above me in the video there's a card that you can click and that will take you to my biology chapter 1 video where I explain in great detail how the scientific method works, what is a hypothesis, you know, how experiments work, etc. Okay, what does it mean to uh falsify a hypothesis or fail to falsify a hypothesis and all that good stuff? So with that being said, uh you know, microbiologists use the scientific method to explain natural phenomenon and describe these germs. They used their observations to form hypotheses. And do you guys remember a hypothesis is a tentative explanation that can be either supported by an experiment or refuted by an experiment. I think of hypotheses as possible answers to your question. Okay? And so scientists, they make an observation and then they formulate a question and then they come up with one or more hypothesis in order to uh try to answer that question and the hypothesis is a possible and testable uh answer to your question. So knowing that these scientists would follow the scientific method where results were published and repeated by other investigators. Eventually the the hypothesis was supported by extensive data and this became a theory. A theory is a viable explanation of why things happen which is yet to be disproved by scientific methods. So I want you to know this. A theory is not just a hunch or a guess. To a scientist, a theory is a verified answer to a uh phenomenon. And accurate mathematical representations of a theory become a law or a principle. So laws and principles are not higher uh in status than theories. They are simply theories that have to do with math and physics. So, let's do a concept check. Another concept check. A scientific theory has little or no evidence to support it. And it could be best described as a best guess. Can you beat Wicked? Is that true or false? That's right. Wicked is always that's false to a scientist. I always explain it to my students this way to a scientist. The closest a scientist will get to saying something is proven is to call it a theory. Okay? So think of it that way. A theory is anything but a guess. So the answer is false. Now how did we use the scientific method in order to discover vaccination? Let's talk about how uh early pioneer in the field of microbiology Dr. Jenner used uh the scientific method in order to discover vaccination. All right, remember that the scientific method begins with an observation. In 1796, Dr. Jenner observed that cows had a form of pox similar to a disease called smallpox. Small pox was a very common uh human disease back in the late 1700s and uh Dr. Jenner noticed that cows would come down with a type of pox which causes spots on the body um similar to smallpox. But then he also noticed that milkmaids who you know milkmaids who would milk the cows they would acquire the cowpox but only on their hands and these milkmaids appeared to be immune to smallpox. So it was rare for a milkmaid to come down with small pox and the milkmaid would develop the cowpox which is like a you know on a human cowpox is much much less severe than small poxes. Okay so he made this observation. So think about it um smallpox is a devastating human condition. However, cows come down with cowpox and milkmaids who handle the cows come down with cowpox but only on the hands and they appeared to be immune to smallpox right so that's an interesting observation isn't it so the next thing is to come up with a question right so obviously Jenner's question would be why are these milkmaids uh you know why are they immune to small pox. Is there something in the cowpox uh lesions that make you immune to small pox? And that led to Jenner's hypothesis. the hypothesis stating that uh Jenner deduced that cowpox was closely related to smallpox and could possibly be used on patients to provide protection similar to that of the milkmaids he had seen. So this is a hypothesis. It's a possible explanation for what he saw. But you have to test the hypothesis, right? the the the way you test a hypothesis is by doing an experiment. So his experiment included he took scrapings from cowpox blisters on the hand of the milkmaid. So he took the the the hand of a milkmaid. He then took scrapings from those lesions to pick up some of that pus, you know, some of that uh sample. And then with that scraping, he inoculated. that means introduced the scraping. Uh he inoculated them to a boy who had not had smallpox. The boy then developed minor symptoms but remained healthy. Next after a few weeks the child was exposed and these were probably not uh the most humane of studies. The child was exposed twice to the pus from an active smallox lesion from a person uh and he did not acquire smallox and he appeared to have immune protection. Isn't that interesting? So essentially uh uh Jenner showed that the boy became immune right by having this pre-exposure to cowpox. he became immune to smallpox. Isn't that neat? And so, uh, Jenner went on to inoculate 23 other test subjects with cowpox. For the first time, he used lesions from one child to inoculate another. All subjects remain protected from small pox. Isn't that neat? So, this showed reproducibility of the results. All the all the people who were exposed to cowpox became immune to smallpox. And you can see here the because of this the countries reporting small pox from 1950 to 1980 has dropped dramatically. This is when vaccines became more prevalent starting in the mid 1900s. And now we have we have actually eradicated small pox. The reason you haven't heard of small pox, the reason why you have you don't know friends or family who have had small pox is because it's been eradicated thanks to the vaccination. Isn't that neat? But if you lived back in the early 1900s or before, you would have definitely known people who had small pox and even became crippled or died as a result of small pox. Next, of course, as any good scientist would do, following the scientific method, Jenner published his results. And so, Jenner wrote a paper detailing his experiment. He called his technique vaccination, which is the, you know, based on the Latin word vaka, which means cow. Isn't that neat? So, vaccines, we can thank cows for the vaccine because the the first vaccines came from those cowpox lesions. Isn't that neat? other local English physicians began to vaccinate patients with the same success, right? With some success and so other other people were able to reproduce his results and and then vaccination theory becomes widespread. Over the next 100 years, vaccination was brought to the rest of the world through local programs. Scientists use generous methods to develop vaccines for other pathogens. The theory of artificial immunity became wellestablished and led to the eradication of diseases and that's what happened next. Smallox is eradicated from the world. Uh the massive vaccination campaign and aim to reduce cases and to stamp out the disease completely. Billions of doses given over a decade reduce smallox to zero zero cases. The last cases occurred in 1977 and in 1979 the disease was declared eradicated. Isn't that a neat success and a great demonstration of how the scientific method works? Other important pioneers in the field of microbiology include John Tindle and Berdinand Cohen each uh who demonstrated the presence of heatresistant forms of some microbes. Cohen later determined these forms to be endospores, these heatresistant bacterial endospores, which we're going to talk about in another chapter. And they determined that sterility requires the elimination of all life forms, including those heatresistant endospores, viruses, and prons. Here are some other very important microbiologists. These are ones who led to the development of aseptic techniques. Dr. Oliver Wendell Holmes observed that mothers of home births had fewer infections than those who gave birth at hospitals. Later, Dr. Ignes Samowise expanded on Hol's findings. He correlated infections with physicians coming directly from the autopsy room to the maternity ward. So imagine this. Uh Dr. Holmes noticed that uh mothers who gave birth in the hospital had worse outcomes than those that had births at home. This is contrary to what we expect today. Right? Nowadays, you're way more likely to have complications with a home birth than a birth at a hospital. But back in the day, you know, back before uh we really understood how germs work in before the 1800s, we didn't know, you know, about germs. So what Samweise did was he realized, hey, I'm noticing that when physicians come from the autopsy room, you know, after doing an autopsy with dead bodies, when they come and give birth or help uh an expectant mother give birth, then next thing we know, either the mother or the child come down with infections. So what happened was Ignes Samoay was the first to really uh introduce handwashing as a policy. Ignes Samoay is known for his policy for handwashing. In fact he said you know when you come from the autopsy room let's wash our hands before we give birth. We before we we deliver that baby. And uh he saw huge improvement in outcomes. far fewer, you know, infant related deaths and infections and better outcomes for the mothers as well. So, in fact, I should add a sentence here that says something about introduced handwashing. Isn't that neat? So, thank you to Dr. Ignes Samowise for introducing handwashing into the medical setting. Joseph Listister was the first physician who actually introduced aseptic techniques to reduce microbes in the medical setting and prevent wound infections. What he did was he used heat or phenol a type of chemical in order to treat his surgical instruments before giving you know uh doing an operation right. So before you do the operation, why not, you know, try to sterilize your surgical instruments? He was the first to really implement that. And lo and behold, no surprise to us living, you know, in the 21st century that, you know, that led to much much better post-operative outcomes. Isn't that neat? And of course all of this led to the germ theory of disease which had two major contributors. Uh again Dr. Louis Pastor that we talked about who disproved spontaneous generation and Robert Cotch. These two are known as the fathers of microbiology. They were able to determine that diseases are caused by the growth of microbes in the body and not by sins, bad character, poverty, etc. Uh this is was a fundamental finding in the field of health care, right? That particular germs cause specific diseases, right? Isn't that neat? This is known as germ theory of disease. And here's a picture of Louis Ptor. Again, Louis Ptor contributed so much to the uh field of microbiology. In fact, Ptor showed that microbes are the cause of fermentation, you know, uh and food spoilage, disproved spontaneous generation, developed pasteurization. And if you've ever heard of pasteurization, you know that that technique lowers microbial loads in foods like milk and wine. And that was a technique he developed. That's why it's named after him. He also demonstrated the germ theory of disease. Uh isn't that neat? So imagine one person contributing all of these different amazing fi findings for humanity. you know, he really was a rock star and one of the fathers of microbiology. In fact, there's technically three fathers of microbiology. Uh, Pastor Cotch and Luen Hook, remember with his pinhole microscope. Those are known as the three fathers of microbiology. And lastly in this chapter, this first chapter, an important concept to understand is this concept of taxonomy. You've probably touched on this uh concept before in a previous biology class, but taxonomy is simply the study of organizing, classifying, and naming living things uh based on relatedness. So it's concerned with classification, the orderly arrangement of organisms into groups and nomenclature, assigning names to those organisms. We also identify determining and recording traits of the organisms for placement into taxonomic schemes. Uh this is a formal system originated by Carl von Len uh in the mid700s. So if you do you guys is this familiar to you? You see these are the levels of classification of taxonomy from most broad being the three domains of life. And do you remember the three domains of life are that's right archa bacteria and ukaria and then all living things belong to one of these three domains of life. So for instance you and I belong to the domain ukaria and then you know once once a taxonomist assigns an organism to one of the three domains it will then place it in the correct kingdom and then in the correct film or division the correct class order family genus and finally species. Right? So that's how we go from most broad level of taxonomy to the most specific uh in the hierarchy of taxonomy. And by the way for this course I would like you to memorize this hierarchy of taxonomy all the way from domain to species. So the way I do that is by using a pneummonic device. I say, "Dude, King Phillip came over for good spices." That's a funny way of remembering the levels of classification in order because a lot of times if I'm talking to you about a type of bacterium, I'll say it's in a class or it's in a family uh or it's in a genus, right? And so you should know what what I'm kind of referring to there. Okay? So remember the levels of taxonomy. These are groupings based on relatedness. Okay. Here you can see the taxonomy of a human versus a single cell ukareot a parramium. See? So a parramium would be grouped into these levels these uh categories in taxonomy. And a human would be uh categorized this way. So let's just break it down real real uh simply. Uh remember a human falls under the domain ukaria but then under the kingdomalia with all the different animals. The film of a human is cordata means has a backbone. So you're in the same group as the other organisms that have a backbone. The class is mamlia. All the different mammals. The order would be primates which are all with all the different primates, the homminids and then the genus homo which means uh you know the the homminids and then the species sapiens. Uh so technically our genus is called homo and our species is called sapiens. And guess what? Our scientific name is a twoword epithet called scientific uh or binomial nomenclature. Have you guys ever heard of bomial nomenclature? Two words bomial nomenclature or uh name scientific organisms. Okay, organisms have scientific names. So for instance, organisms always have a two-word name like homo sapiens. This is known as our binomial nomenclature. It's our scientific name. The first word refers to our genus. The second word refers to our species. So technically we are in the genus homo and the species sapiens. By the way, the genus has to be capitalized. Okay. And the species is lowercase. And notice that the entire word is italicized. If it's typed, you see how it's typed here? It's italicized. If it's handwritten, normally it's underlined. Okay? You have to do all of that to do proper binomial nomenclature. So, let's look at this one on the on the right. You're talking about this uh parramium. And notice that this guy is in the genus parramsium and in the species codatam right so this guy's or uh spec scientific name this single cell protozoa's scientific name is parramsium codatam again notice that parramsium is capitalized it's the genus name codatam is lowercase It's the species name. And then notice how the whole thing is italicized. That is proper binomial nomenclature. So let's do concept check number five. Organisms in the same family must also be in the same class. Well, do you guys remember how it works? If you're in the same family, are you also in the same class? Yes, you have to be, right? because family is more specific than class. So the answer is true. A. Now next one assigning scientific names. Again do you guys remember binomial nomenclature genus is capitalized species is lowercase and then do you guys remember it's either italicized or underlined. So for instance, you guys have probably heard of this staflacus orius. Staflacus is the genus orius is the species. Sometimes they'll even abbreviate it to s orius. So the s stands for staflacus, right? But either way, it's still italicized. Does that make sense? So always for uh always um remember to italicize scientific names or underline them. Okay. And then the last last concept on this uh uh chapter is a little bit about the origin and evolution of microorganisms. There's this concept of phogyny natural relatedness between groups of organisms. And this is thanks to evolution. All new species originate from pre-existing species. There was a original last common ancestor and that's which branched off all the different domains of life and all the different creatures we know today. Closely related organisms share similar traits because they evolved from common ancestral forms and evolution usually progresses towards greater complexity. Here we can see how the earliest cell uh appeared about 3.5 billion years ago and they gave rise to the three domains of life right archa bacteria and ukareia right uh and now we have all these different uh uh branches of taxonomy okay so again the three domains of life are bacteria archa and ukaria and by the way Remember bacteria are proarotic. Archa are also proarotic but they tend to live in extreme environments and only the domain ukaria is made up of cells that have ukareotic uh you know architecture. Okay. And so that's it. Uh I think that leads to the end of chapter 1. Thank you guys for joining me. I hope that was informative. Please leave any questions in the comment box below. and welcome to the course. Let's uh have a fun semester of it. Next, we'll be talking about chapter 4. So, let's go ahead and get started. Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D. A doctor, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D, Dr. D.