[Music] [Music] today we're going to have a discussion about bacterial morphology and shape and this characteristic about bacteria is very important in terms of naming of the bacteria defining the bacteria and helping to classify according to various qualities that we have been discussing in the last few lectures so the morphology and shape can take on various qualities including these Spears and also the kama structures and the appearance of the flagella and also they can look like spiral worms so in terms of the classification they're based on several major properties the cell wall the morphology metabolic behavior infection patterns whether or not they're obligated to be intracellular or antigenic composition and DNA sequence now we are discussing each one of these characteristics separately in in several lectures so today we're actually going to talk about morphology future lectures we'll talk about the other qualities so the classification really of bacteria is is very challenging endeavor we've discussed that in other lectures and the reason it's so challenging is because bacteria are very complicated they're complicated in terms of how they live how they reproduce how they acquire characteristics that they didn't have before they don't engage in sexual reproduction they engage in various forms of budding and sharing of DNA and so forth that are different from the classical reproductive patterns that occur in other animals so higher organisms as we know are classified according to visible anatomical criteria and these classical criteria are what are for the basis of zoology and taxonomy so bacterial species as I mentioned some of them are very similar to one another but they and and they recombine into new strains that again have not occurred before classifying these strains of bacteria really can't be done morphologically because they don't look that different from one another however biochemically they behave very differently but on the other hand these morphological differences do exist between major groups of bacteria and they're important to understand in relationship to classification so these variations and shapes and distribution so it's not just the shape that varies but also how these bacteria are organized together so we can of course have singular bacteria now the coxy shape refers to a rounded spherical shape and you can see they can occur singularly they can occur just two of them the diplo coxy and they can occur in pairs surrounded by a membrane or actually it's not even a membrane it's a capsule so we'll see those as well you can have these staphylococci which are under a grouping of coxy you can have streptococcus a which are basically linear arrangements of these coxy shapes and so forth now the bacilli that's another word bacilli is another word for rod okay and these rod shaped bacteria or bacilli can also be arranged singularly they can be arranged in Chains and they can be arranged in these structures called Palisades and they can also be arranged in angles from one another we can have these budding --zz different kinds of appendages and bacteria we can have these Vibrio shapes which are like commas we can have a corkscrew form and we can have a filamentous form so all of these forms actually also help to name the bacteria so some of the bacteria are named truly according to their shape and their arrangement so here is how bacteria are actually arranged and of course they're arranged by how they reproduce so for instance these chains are where we have the cell division of bacteria that occur in one plane and when that happens they form these chains we can have them the reproduction or the cell division of course occur in packets where the replication the division actually occurs perpendicular to one another and then they form these nice symmetrical packets and then we can have clusters which is more of a random arrangement where these cells divide in various different planes so then you get a cluster so again the shapes of bacteria you can't learn you can't see that enough and once it's ingrained in you you will truly remember these and when the exam comes along you'll score an A+ as far as remembering bacteria according to shapes so we have again the pneumococcus or they have that capsule surrounding the two Diplo we have streptococcus E which are chains we have staff that are remember the cell division is random so they get into these clusters we have Mycobacterium tuberculosis which we'll talk about later on and those are bacilli shaped right in Chains we have spores and then we have these spirochetes or spirals so the bacterial shapes essentially assume one of three qualities or one of three shapes they can be spheres they can be rods and they can be curved and the names that all the spheres are called coxy the rod like shapes that are called bacilli or bacillus and the curve shapes are called Vibrio or spear eleum or the spirochetes so but within those three basic shapes are considerable variation and also these cells can be stretched or compressed and certainly when they're visualized they can change shape and so forth but in general they can be arranged according to one of these three shapes so bacteria now as I mentioned before the way they cluster together has to do with the way they engage in cell division so they can form clusters they can form chains and all of that is related to how they divide so again to repeat that so some coxy in relationship to dividing always are found in pairs and those are known as diplococci and we saw that there were streptococcus pneumoniae which is a pneumonia bacteria and we also have Nasiri gonorrhea which is a gonococcus and we'll be talking about these groups of bacteria quite frequently in other lectures so here we have the streptococcus pneumoniae and you can see the capsule that surrounds these gram-positive bacteria they are always arranged in pairs now remember gram-positive what is gram positive that's where that cell wall is on the outside so we always have to go back to the beginning and remember what these qualities are because it'll help you remember absolutely so these diplococci are two spherical shaped bacteria and in relationship to the pneumonia they are surrounded with a capsule so the streptococcus II remember our long strands of beads so they're they're arranged as you can see in this histogram they're arranged in these linear shapes the staff are arranged in random clusters how do that how does that occur remember it occurs through how they in what pattern they actually engage in cell division so one way that I like to think about so I like to think about how the streptococcus II are different from the staphylococci and we'll get to that question example at the end of the lecture but these kinds of terms are really important to remember and unfortunately they sound very similar so you have to stop for a second and tune in and remember what they mean so these coxal bacteria can occur in square or cuboidal packets now remember again that has to do with how they divide the rod-shaped bacilli are long-chain they can become long changed they can also be single they can also be on their own and they can also acquire or they can actually be arranged in these angles from one another and sometimes the angles can be random but they still have that rod-like shape so that's very different from the coxy shape and the bacilli of course have pointed ends and they're comma shaped and so these comma shaped rods then are known as Vibrio and these Vibrio for instance Vibrio cholera is a very important waterborne bacteria and it causes the disease cholera and will be certainly talking about cholera in other lectures in the course but you can see sometimes the Vibrio have La Jolla and sometimes they don't so to continue with our shapes we can have thus Parrilla che which are bent so here's an example of the spur Illya and you can see it can be twisted and it's surrounded by a cell you know cytoplasmic material and then the spirochetes are a corkscrew looking bacteria and they form a helix and the helix is formed around the axial filament so we'll see examples of them in other discussions so the first question has to do with what is the difference between streptococcus and Staphylococcus they sound very similar but one way that I like to that reminds me of what streptococcus is is I think about the word strep toe and to me that sounds a lot like Street and streets are usually straight so streptococcus really a linear arrangement of these spherical bacteria whereas the staff remember is more of a random arrangement and the random arrangement often looks like clusters of grapes so the difference between the two I mean they certainly have other differences in terms of infection patterns and so forth but as far as the shape they both are coxy however they're arranged in different ways now how do the groupings of bacteria originate we talked about that in a couple of slides they have to do with the cell division so remember if the cell division occurs you know in a plane in the same plane they're arranged in Chains if they occur perpendicular to one another they form those nice symmetrical packets and if they're random they occur now what I mean by random is that the plane of cell division is random then the clustering is random as well so that's actually how the groupings occur based on the way cells divide now the third question is what is the difference between staphylococci and staff a low back Tyria now this is a trick question so we're gonna go through and dissect exactly how this is a trick question and these are the kinds of questions that if you know the material really will you'll see the flaw in the question and that's really important so first of all let's dissect staphylococci now remember coxy is the rounded shape and remember the staff and you can remember the staff if you also remember the strep now remember the strep or in linear chains and the staff are in random clusters so the staphylococci really are random clusters okay so then the next one is staff alope bacilli now you're gonna say oh okay staff love bacilli that must be a random arrangement of bacilli wrong remember we don't have staff alow bacilli however we have strep toe bacilli okay and what is strep now it's a linear arrangement now what is bacilli those are rods it's a linear arrangement of rods so if you're faced with a question like this you know straight off the bat the question is not correct thank you so much for visiting educator com