biology and medicine videos please make sure to subscribe join the four main group for the latest videos please visit facebook armand please like and here you can also ask questions answer questions and post some interesting things including artwork so you can send it to me and you can also change the quality settings the highest one for better graphics in this video we're going to talk about bacterias and it's just going to look at the structure specifically so bacteria bacteria are the largest group of microorganisms or medical significance and so that's pretty important to know because they are literally everywhere bacteria occur in three main shapes caucus a circular shape sphere a bacillus a rod shaped and a spiral now there's also other uh different shapes bacteria can take such as a cocoa bacillus which is in between a coccus and a bacillus and there's also one a bacteria can take shape of a what's called a vibrio and it's sort of spiral and bacillus in between it's sort of gonna bend to it now some bacteria are surrounded uh by polysaccharides containing capsules so a capsule containing polysaccharides um now this capsule also known as a slime layer actually allows the bacteria to bind to surfaces of different cells in our body for example and also to evade phagocytosis to avoid phagocytosis so it's very important essentially for the bacteria survival so what other parts does a bacteria have what other structures do a bacteria have here i'm drawing a rod-shaped bacteria it can be any type of white shade bacteria and now let's learn about part of its anatomy some bacterias have what's known as a flagella which are thin rigid filaments and these allow for bacterial movement flagella are essentially made up of proteins and these proteins can move can propel the bacteria forward or move it around bacterias can also possess hair-like appendages coming out of their surface there are two types of hair bandages fimbriae and pili and these are used interchangeably a pili is typically shorter than a fimbriae but they essentially do the same thing the fimbre contributes to the bacteria's ability to cause a disease by binding onto a surface of a cell in our body for example and this can also be done by the pillow the pillar is another hello heroic appendage just like the fimbriae and the pillar help attach the bacteria to mucosal cell surfaces and the pili are also involved in what's called bacterial conjugation bacterial conjugation is essentially the transform the transfer of the genetic material of a bacteria from one bacteria to another by forming a bridge using a pili now let's look at the different layers a bacteria has the bacteria's outermost layer is known as a capsule and as and as we know it it has polysaccharides which enables it to bind to cell surfaces and also avoid phagocytosis such as avoiding macrophages and also neutrophils the bacteria's innermost layer is known as a plasma membrane and plasma membranes we are also found in human cells for example in eukaryotes and the structure is very similar in both bacteria and humans the plasma membranes are semi-permeable membranes allowing transportation of substances in and out of the cells and plasma membranes as i mentioned in bacteria are similar to those in humans in that in that in in bacteria the plasma membrane are also is also a phospholipid bilayer and contains proteins as well within the membrane the phospholipid bilayer is made up of molecules known as phospholipids a phospholipid has a hydrophilic region which means a region that loves water hydro as in water philic as in love and also has a hydrophobic region hydro as in water and phobic as in skin and this characteristic of a phospholipid basically enables it to form the phospholipid bilayer and so that's for the plasma membrane now in between the capsule and plasma membrane we have the cell wall and this is a very complex semi-rigid structure and the cell wall enables bacteria to be classified into two major groups gram-positive bacteria or gram-negative bacteria and there is a difference first of all they are grouped into gram-positive and gram-negative bacteria because when you dye them with different dyes they have different colors and the different colors are caused by the different cell composition of both these types of bacteria so what is the difference in cell wall composition well the gram-positive bacteria has a cell membrane with a structure above it let's just say here's the outside of the bacteria and here is the inside of the bacteria so here we have the cell membrane and the structure above it is known as a peptidoglycan and is composed of amino acids and sugars the gram negative bacteria also has a cell membrane but it has a very thin peptidoglycan layer compared to the gram-positive so gram-negative has a thin peptidoglycan layer the gram-positive has a thick peptidoglycan layer in addition to that the gram negative has an extra cell membrane above this thin peptidoglycan layer the other notable difference between gram-positive and gram-negative bacteria is that the gram-positive bacteria has what's called a lipo tercoic acid which enables it to bind to cell walls or be recognized by macrophages or agrocytes the gram-negative bacteria on the other hand has a lot of lipid-like structures on the outer cell membrane such as lipoproteins and also what's called lipid a lipid a are toxins and they cause certain diseases and shock syndromes within the human body so now because of these different cell wall compositions when we use dye these bacteria depending on what type of cell composition it has will have a different color the dyes used to stain a particular bacteria in successive order is crystal violet and then we use iodine treatment and then we decolorize it using alcohol and then we use finally safranin and essentially i'll make a video hopefully on how this process works but essentially the bacteria with a thick peptidoglycan layer and one cell membrane will have the crystal violet color which is bit purplish at the end and the gram and the bacteria which has two cell membranes and a thin will have a pinkish red color and so this is how we classify the bacteria if it has a purple color after being dyed it's a gram positive if it has a pinkish color after being dyed it's a gram-negative hope this makes sense so now now that we know about the layers of the bacteria has let's look at the cytoplasm of a bacteria cytoplasm contains water enzymes ribosomes and circular dna and this is the fundamental difference between a bacteria and a eukaryote or human for example so ribosomes are as we know are the site of protein synthesis and they can be found all around the cytoplasm here the dna in bacteria is is circular and not linear such as the dna in humans but it should be noted that humans also have circular dna in the mitochondria but anyway the main dna that make up the bacteria are in a circular form and they're all tangled up and this is the genetic material and we also have additional genetic information genetic material known as plasmids that are in the cytoplasm and they're not part of the circular dna they're they're like a circular small circular genetic information around the cytoplasm and plasmids as i mentioned um have additional genetic information and they could be incorporated in the circular dna the big one or they could be transferred between two bacterias through conjugation to the through the fimbriae or pili so that's all on the bacterial structure in the next video look at the bacteria's growth reproduction and also classifications