Welcome back! This lecture, we will talk about the organization of organisms, we'll discuss the three domains and the five kingdoms, we will talk about bacteria and the importance of bacteria, and we'll also go over cell theory. Organisms are grouped in different ways by different biologists. Generally, they are grouped by likeness of related ancestors, and this is called philogyny. Philogyny is when organisms are related through previous ancestors, and they get grouped together in certain categories. You can see on the left here we have a slide showing you the three domains. The three domains are grouping organisms in a very broad category. This is the broadest categorization of biological organisms. The three domains are the bacteria, the archaea and the eukarya. And those are listed at the top here. Your bacteria, your archaea and your eukarya. Your bacteria are normal everyday bacteria. They are bacteria that give you strep throat. They are bacteria that give you lymes disease, and they're also bacteria that live normally on your skin or in your digestive tract to help you digest food. All of us are surrounded by bacteria all the time. Not all bacteria are bad, not all bacteria make us sick, and it's actually the bacteria that are very helpful in many different ways that we'll discuss. The next group of organisms are called archaea. Archaea are bacteria that are a bit more extreme. They can live in extreme salt, those are called halophiles. They can live in extreme temperature, those are called thermopiles, and you can see down here, those are listed. Methanococcus would live in extreme methane. You also have methanobacterium, also living in extreme methane. So lots of these are going to be able to live where most other organisms would not survive. Our third domain is eukarya and eukarya pretty much encompasses everything that is not a bacteria or an archaea. This would include all protists, which we'll talk about, all plants, and all animals, and all fungi. And eukarya are going to be eukaryotic cells again we'll discuss that, whereas the bacteria and the archaea are what we call prokaryotic cells. Now we said the three domains is the broadest categorization of organisms. The next step down from that, slightly less broad of a categorization level, would be the five kingdoms. The five kingdoms, you see here, are Monera, protists, plants, animals, and fungi. Those are a little bit more exclusive compared to the three domains. The first Kingdom at the very bottom is Monera and Monera is going to include all of the bacteria. So, it's not going to separate them out like we saw with the three domains and here is your Monera down here. These are all procaryotic organisms, they are all unicellular, they're going to absorb nutrition or be capable of photosynthesis, some will be motile, they can move, some will not be able to move, and they are going to reproduce asexually. The second Kingdom are the protists and protists are right here. These are going to be our first group of eukaryotic cells on the five-kingdom scale. These are going to be either unicellular or multicellular, they are capable of absorbing nutrition, ingesting nutrition, or also photosynthesizing, and some can actually eat they can ingest, and they can photosynthesize, they can also reproduce sexually or asexually. Making our way to the top of this five-kingdom chart we have the kingdom plants, or Plante. Over here plants are going to be eukaryotic organisms, they are multicellular, they photosynthesize, and they reproduce a sexually. In the middle of the top up here we have the animals. Kingdom Animalia, as it says, all the animals, they are eukaryotic organisms, multicellular, they're going to ingest food, they are movable, they're motile and they reproduced through sexual reproduction. And finally, all the way over on the edge here we have the kingdom fungi. Fungi are eukaryotic organisms, they are multicellular, absorb nutrition, non-motile, and reproduce through sexual reproduction. We will talk about each of these Kingdoms in a little bit more detail but we'll go through them again right now and reintroduce them and then we'll start talking about cell theory, why cells are so important, what makes up a cell, and then we'll talk about bacteria. So, our first Kingdom, remember all of the bacteria, while they were separated out in the three domains they are lumped together in the Kingdom Monera and these are our only prokaryotic organisms. We'll talk about protists which we already mentioned are eukaryotic organisms they are also unicellular. So please try to keep prokaryotic separate from protists. A lot of students get them mixed up and in lab we will actually look at the protists and you'll become very familiar with those. All right, so the kingdom Monera again prokaryotic, these are your bacteria and archaea, they're unicellular, they generally are going to absorb nutrition, but there are a few that are photosynthetic, those are called cyanobacteria, and we'll talk about those later. Most bacteria can move they can have a flagella, but some will be nonmotile and bacteria reproduce through asexual reproduction. Next is the Kingdom Protista these are eukaryotic, many are unicellular but there can be some multicellular organisms. This here are your algae, this is a phytoplankton algae, you can see in this picture here this is called a paramecium, a freshwater species and an amoeba. And eukaryotic organisms are going to all be defined by based on cellular membranes that we'll talk about in a little bit. In the Kingdom Protista, these organisms can absorb nutrition, they can ingest nutrition, and some will be photosynthetic. You can see here these algae obviously are photosynthetic you can actually see the chloroplasts inside them and organisms in the Kingdom protista can reproduce sexually or asexually. Our next Kingdom is Plante, these are plants, all photosynthetic eukaryotic, multicellular organisms, that are going to reproduce sexually. Our kingdom Animalia, all of our animals, everything in the animal kingdom, all eukaryotic organisms, multicellular, they're going to ingest their food, they can move, and they reproduce sexually. And the kingdom fungi, eukaryotic organisms, again multicellular, they're going to absorb nutrition, and they are nonmotile, and reproduce sexually. And just another look at these together, in the domain bacteria you have normal everyday bacteria, we call those eubacteria and that's the kingdom Monera. You also have the domain archaea, which are your extreme bacteria, these are in the Kingdom Monera. Then all of these organisms over here are going to be in the domain eukarya, you have the protists which are in the Kingdom Protista, the plants which are in the Kingdom Plante, the fungi which are in the kingdom fungi, and all of your animals in the kingdom Animalia. And while we're on the lines of philogyny and we're talking about how we're grouping organisms let's talk a little bit about taxonomy because this is philogyny, but it takes a little bit of another step further and here you see the taxonomy of humans. At the bottom we have Kingdom which we've already discussed as a very broad category. a very inclusive category and as you go up this chart from Kingdom to phylum, class, order, family, genus, species. You get more and more exclusive. You're starting to leave different organisms out so at the Kingdom level you have all of the animals on this taxonomy scale. At that next level, phylum, now you are narrowing it down to the chordates, the animals with backbones. Then class is a little bit more narrowed down to just mammals. Order would narrow those mammals down just to primates. Family would narrow them down just to hominids. Genus would narrow them down to homo and at the species level sapiens. Homo sapiens are humans. So, you can see in taxonomy again, this is very similar to philogyny, and we'll talk about this again throughout the semester but it's just another way of grouping organisms with common ancestors and starting to exclude different organisms that aren't like them. Let's discuss cells. We've talked about cells a bit we've talked about prokaryotic versus eukaryotic cells and we've talked about unicellular one cell versus multicellular, so what is a cell? A cell is the smallest unit of life, and it is also the basic unit of biology, and every living thing is made of cells. There are some truths about cells and we call this cell theory and cell theory states that all living organisms are composed of cells. Again, cells are also the basic unit of life, and cells come from other cells through cell division. The last point in cell theory is that all cells contain heritable information, and this heritable information is in the form of DNA or RNA. Now let's discuss some common features of cells, as we said in cell theory all cells have genes made of DNA. We will spend quite a bit of time talking about genes and DNA. All cells have ribosomes. Ribosomes are an organelle inside a cell that is going to make proteins. Finally, all cells are going to be bound by a plasma membrane. Some cells will have a cell wall outside the plasma membrane and some cells will just rely on the plasma membrane. The first type of cell that we'll talk about are the prokaryotic cells and recall that these are the bacteria. Prokaryotic cells are ancient cells. They are pro meaning before and karyot meaning nucleus, so these cells developed before we had a membrane-bound nucleus prokaryotic cells have no plasma membrane around their DNA they do have DNA all of this material inside the cell here this is the DNA. However, it is not contained inside a nuclear membrane or any kind of plasma membrane. Prokaryotic cells are going to be in the Kingdom Monera and in the domains bacteria and archaea and procaryotic cells are very small cells. They are much smaller than eukaryotic cells and in fact they are smaller than some of the organelle the structures inside the eukaryotic cell and on this chart here you can see where bacteria are, and slightly larger than your bacteria are the mitochondria these are an organelle inside a eukaryotic cell. And then you can see up a little bigger are most plant and animal cells. Again, bacteria are very small cells. This is just another way to visualize how small you bacteria are or prokaryotic cells are. The prokaryotic cells are the bacteria and again on this slide you can see the bacteria here and then your animal and your plant cells here. So, bacteria are quite a bit smaller than any eukaryotic cell and as mentioned the prokaryotic cells are going to be both domains bacteria and archaea. Bacteria and archaea and they are going to be in the Kingdom Monera way down at the bottom the kingdom Monera are all of our bacteria and these are prokaryotic cells. Let's talk in more detail about bacteria. Bacteria are some of the oldest living organisms dating back to anywhere from 3 and a half to four billion years ago so very, very old ancient organisms. Again our bacteria are unicellular, uni one cellular cell, so they're only going to be one cell big. They are prokaryotic so they're only they're not going to have a defined nucleus they still have DNA it's just not confined to a membrane bound nucleus. We mentioned their size they are extremely small, and they're very successful competitors. They live everywhere. They are extremely abundant, and they live in every condition. Remember those extremophiles can live in extreme salt, extreme temperature, extreme methane, and there is a ton of diversity to bacteria. There are thousands, tens of thousands, probably hundreds of thousands of bacteria. And recall that the archaea are the extremophiles, the extreme bacteria, and then the bacteria the domain bacteria are our eubacteria, our everyday bacteria, normal bacteria. Let's talk about bacteria shapes. Bacteria can come in these three main shapes. There are the cocci which are small little spheres, streptococcus, if you've ever had strep throat that's an example of a cocci bacteria. Bacilli are these small rods that an example of that would be lactobacillus which is in yogurt, probiotics. Finally this spiral shape a spirochete and an example of that would be lymes disease. We mentioned that archaea are our extreme bacteria and let's talk a little bit more about what that means because recall we said they can live in extreme temperatures, extreme salt, extreme methane. This is a picture here of Yellowstone National Park. I took this picture, hopefully you all get a chance, either have been, or get a chance to go to Yellowstone National Park one day because it is gorgeous. There are lots of thermal pools there these pools are extremely hot. If your foot, if your body, if any part of your body touches these poles your skin will singe right off. They are extremely hot, yet you can see these different colors around the pools. You can see browns, oranges, whites, blues. These are all different bacteria that are capable of living at this extreme heat. These bacteria that can live at extreme heat are called Extreme thermopiles. Thermo is heat and they thrive in this heat. What is unique about these bacteria is they have specialized proteins that can handle these different conditions. Normal proteins can only handle a certain temperature range. They will fall apart at very hot temperatures. Therefore, the bacteria that live at it these extreme temperatures must have specific proteins adapted to this heat so that they don't fall apart. We also mentioned the bacteria that live at extreme salt, these are extreme Halophiles salt the Halo, -philes loving, and these are going to thrive in extreme salt. And these bacteria again have specialized adaptations to be able to live in the pH of very high salt content. And lastly in archaea we have chemotrophs. Chemosynthetic bacteria. These are bacteria that can actually live off of chemicals, live off of methane, or whatever they are adapted to live off of and these are really important bacteria to have because they help process these different chemicals. We also mentioned eubacteria and these are your common bacteria. These bacteria play a vital role for life on Earth. And we'll discuss some of these roles of bacteria but it's important to think about what bacteria to eat or sorry what bacteria eat to think about what their roles are. So we mentioned that the bacteria have very very diverse nutritional capabilities we have the chemotrophs that we mentioned they get their energy from chemicals usually methane and then there are two other sources of carbon used by prokaryotes. You have the autotrophs which make their own food, those would be photosynthetic organisms, and in bacteria they would be cyanobacteria. And then you have the heterotrophs, and these are bacteria that are going to eat anything else. And these bacteria all have very important roles in all of our lives all around us. First remember that not all bacteria are bad and this is important because bacteria really do play critical roles. They can protect against more harmful bacteria so by having bacteria around us all the time they can fight off certain bacteria that can be more harmful to us. Mentioned before, we discussed that bacteria can help you digest nutrients in your digestive tract. Some animals actually rely on bacteria to help them process food. Cows are an example of this. Cows actually have a chamber of their stomach with bacteria in it to help them break down plant matter. We have plenty of normal bacteria in our gut tracks and if you've ever taken an antibiotic and your doctor recommends having a probiotic that's to help reflourish, repopulate all the normal bacteria in your gut because when you take antibiotic you are killing the bacteria. Antibiotics. Bacteria can also help clean up the environment. This is called bio-remediation and bacteria can be used to digest oil. They can digest oil in oil spills or if oil has seeped out of a container on land. You can use normal bacteria that eat that bacteria to help clean up the soil or the ocean. Bacteria can also be used to help decompose organic matter and a big process a big part of the sewage treatment process is using bacteria in these settling pools to help digest sewage waste. I know it sounds kind of gross, but sewage treatment plants are there to help break down all of this matter before the water ends up back in the ocean and bacteria play a big role in that. And again, what bacteria eat is very important to this because the chemotrophs can help break down chemicals the autotrophs are going to photosynthesize, the cyanobacteria, and then the heterotrophs are ingesting other nutrients and organisms for organic matter. So, they're all playing these critical roles in our lives every day that we don't even notice. You don't see them, you don't notice them, however, when you get sick you really notice it. If you ever had strep throat, you know you have some kind of infection in your throat. It hurts. You have normal bacteria on your skin and if you've ever scratched your skin and it's gotten infected then you've gotten bacteria inside that cut so normal bacteria are good but when things go awry right it's not so good.