 Tracic! Hey everybody, Dr. O here, in this video we're going to cover the common bacterial cell shapes and arrangements. So I'll just go right through the list here. So first we have a caucus. So a caucus would be the singular, a cocci would be plural, that's going to be a round or a spherical cell. Bacillus means rod. So technically the bacillus can be used in two ways, like a bacillus is used as a name and as a shape. So it's like my name is Frank, right? So Frank would be my name, but a Frank would also be a hot dog, I guess, right? So if you see bacillus and it's capitalized and it's part of the name of an organism, it is part of its name, but it also is telling you that it has a rod-like shape. So caucus means sphere, spherical organism, bacillus is rod. Next we have vibrio. So it's technically a curved rod, but they look like a comma. So there's so many examples of the cocci and the bacillus that we'll cover them as we go. But the really only the key example of a vibrio that we're going to talk about very much is vibrio cholera, the causative agent of cholera. Next we have the cocco bacillus. So these are actually short rods, but they're so short that they can look like spheres. So they kind of, they can be misinterpreted sometimes. So a cocco bacillus is a short rod. Quite a few examples here. Important ones, I'll see hemophilus influenza, which is the, can cause meningitis. Bordotelo pertussis, which can cause, which causes whooping cough. Those would both be examples of, of cocco bacillus or cocco bacilli organisms. Next we have the spirulums. These are rigid, large organisms that are, that are spiral or corkscrew shaped. Not any really important clinical examples here, but I do want to point out that the spirulums and the spiral keats, they're both examples of spiral organisms, but there's, there's a couple of clear differences here. Spiral keats are also going to be corkscrew shaped. They're going to be more flexible, but here's the key difference. The spirulums organisms, they're going to be propelled by flagella. On their ends, the spiral keats, they use a special kind of flagella which is called an axial filament. So that's going to be the key difference there. And then clinically, the spiral keats are a lot more important. The two key spiral keats that I can think of here would be trepanema pallidum, which is the causative, causative agent of syphilis and berylia burgdorferi, which is the causative agent of Lyme disease. And there are other ones. All right. So those are the basic cells, shell shape, cell shapes, say that three times fast. Caucus, bacillus, vibrio, coco, bacillus, spirulum, and spiral keats. Now let's move on to the cell arrangements. So if you just have a single organism, it would be a caucus or a bacillus. No need to go over that again. Diplo means two. So if you have a pair of spheres, it would be a diplococcus. A pair of rods would be a diplobacillus. The most important diplococcus would be your streptococcus pneumonia. I know the name tells you it's in chains, but it's, it's a diplococcus most of the time. Tetrad, we don't talk about that much. That'd be a group of four. If you want to go even further into a group of eight, that's called a sarcine, but that's not a big deal. But the two key ones here are strepto means chain. Staphylo means caucus, means cluster, sorry. So you think, so strepto and staphylo and then caucus and bacillus, most the organisms that we're going to talk about are going to need those terms to describe them. So strepto means chain. Staphylo means cluster. Notice here, we have a streptococcus and we have a staphylococcus, but we do not have a staphylo bacillus. So a streptobacillus is a chain of rods, but rods don't actually grow in clusters. And that's because rods grow end to end. They don't grow, they don't grow side to side. So you're not going to, if you see a cluster of rods, it's only because they're in a pile. It's not because they grew that way. So there is no strepto or staphylo bacillus. Okay, so those are going to be all your key terms as far as cell shape and cell arrangement for your bacteria. Have a wonderful day. Be blessed.