okay so we're going to start with a brief review of what we are going to be talking about in the whole course meaning different types of microbes the structure which branches of microbiology study them so microorganisms we broadly divide them into several categories category number one bacteria and archaea as you will see soon it is a very artificial grouping but these two types of microorganisms what's common they all are prokaryotic which means they do not have nucleus or membrane-bound intracellular organelles and they always unicellular so um immediate question they are always union cellular why the short answer is we have no idea the modern science suggests that most likely they are always unicellular because they lack sufficient communication between the cells now question mark means that we don't really know if it's true okay so the branch of microbiology that studies bacteria and archaea is bacteriology you know not the rocket science next group are fungi so fungi are eukaryotic they can be unicellular we call such fungi yeasts for multicellular we call such fungi molds and the branch of microbiology is studying this is mycology then we have protozoa now i want to focus your attention it is not a taxonomy so it's not like genus or phyla or classes it's just breakdown on the structure by the structural features protozoa by definition are unicellular eukaryotes so we just place all unicellular eukaryotes well except some into the same group okay protozoa usually fall in the realm of parasitology studies as well as helmets ailments are the second best microorganisms they are eukaryotic multi cellular always multicellular organisms so that's actually the only always multicellular organisms that we're going to be looking at also studied by parasitology now we have two more we have viruses and algae we're going to put algae first and that's i believe the ultimate time we talk about also we can talk about them one more time so algae are eukaryotic it can be multicellular or unicellular and they are studied by the branch called phycology now these ones viruses are absolutely the best microorganisms and these are a cellular viruses do not have a cellular structure which means they are non-living viruses are not considered to be living things studied by biology now the name of the subject that we are working on in this class is microbiology right which means small so how small to answer this question we need to highlight whether we can look at microbes using light microscopy or electron microscope i'm going to be saying a phrase in most cases a lot basically there are a lot of exceptions in microbiology so bacteria and archaea in most cases light microscopy is fungi well practically in all cases light microscopy is enough protozoa definitely light microscopy is enough helmets you can look at them with a naked eye in overwhelming majority of cases however there are i can think of at least one schistosoma that you would need a microscope to look at but light microscope algae naked eye obviously or light microscopy and finally viruses so viruses overwhelming majority of them you can see only using electron microscope now again majority of cases so if i ask you a question can we see some viruses using light microscopy yes can we see actually some bacteria with a naked eye surprisingly yes there's like a couple of species that are large enough tiny tiny tiny little ones but you can see those that make sense so you should be able to answer the question to characterize like which of the following characterizes helmets or protozoa or bacterial fungi okay without any sort of further ado let's talk immediately about the taxonomy and and how we classify microorganisms so first of all the classification what do we base it upon there are two classification systems the first one was introduced by whitaker so whitaker classification groups microorganisms based on the appearance the ecological niches basically phenotypical similarities okay and you probably saw this in the lecture notes there's a little little tree with manera protista fungi plantai and animalia okay does that make sense so these are five kingdoms so whitaker included manera all prokaryotic organisms okay in one kingdom all unicellular eukaryotes in another kingdom protista placed all fungi right here yeasts are not here okay and then plants and animals kind of obvious thing right so and it worked pretty well because you have to understand taxonomy is an artificial science i mean it's not a science it's just artificial product you know you can you can organize your uh your clothes based on the size based on the length based on the color i don't know material whatever so another scientist carl rose was working on genotyping bacteria and to make a long story short he came to an experimental observation and a conclusion that we have to reconsider the classification so uh woes fox system that is the main system accepted in the biology now is based not only phenotypical similarities but only similarities between the 16s rna gene the woes uh the premise that carl rose was operating on was as follows closely related so he said that there are some very very conserved genes genes that are not changing a lot does that make sense and the organisms that are closer to each other will have those genes much more similar so for instance our 16s rna gene and human primates 16s rna gene okay will have an enormous amount of similarity but if you compare hours to two mice similarity will be much less you following me so this similarity suggests that two organisms are evolutionary closer and are in a in a closer relationship genetic relationship so based on these observations woes changed kind of you know reconsidered this whole classification scheme saying that there was uh last universal common ancestor i know there is a cartoon now streaming somewhere on tv and then it produced bacteria okay and the second branch actually split into archaea and eukarya so those are three domains of life okay does that make sense so basically the idea that carlos had was that the initial last universal common ancestor evolved producing a group a domain of bacteria domain of archaea and domain of eukarya and if you look at this what's called phylogenetic tree you can see that ikea and eukarya are closer to each other does that make sense well bacteria is farther from them it's kind of a bizarre because under the microscope let's say bacteria and archaea look very very similar well you can imagine archaea that are prokaryotic are structurally very different from eukaryotic organisms it's basically the same situation when you have a brother and a sister and they have a cousin and brother and sister don't look alike however two cousins look very similar but genetically they are more distant is that clear it makes sense okay now how do we name organisms we use binomial nomenclature where you have name one and then name two okay so name two sorry name one designates the genus and both name one and name two designates species so for instance staphylococcus aureus staphylococcus aureus belongs to the genus staphylococcus represents the species staphylococcus the psilocybilis belongs to genus bacillus as a species bacillus substance does that make sense questions on this one viruses fall into their own category um both the exonomial viruses is very it kind of should show um kind of complicated because they're no they're not living you know cells so it's really hard to assign species versus general versus families and so on people try as well as naming naming is another big problem any questions on this part no we're good okay awesome