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Current time:0:00Total duration:18:26

Video transcript

I think we've all heard of the word bacteria let me make sure bacteria and we normally associate it with kind of negative things as you say bacteria those are germs so we normally associate those with germs and they indeed are germs and they cause a whole set of negative things or at least from our you know kind of the the standard point of view people believe that they cause a whole bunch of negative things so just let's just list them all just to make sure we we know we know about them we're all on the same page so the the bad things they do they cause a lot of diseases tuberculosis tuberculosis Lyme disease Lyme disease I mean I could go on and on they you know pretty much anytime well I'll be careful here whenever people talk about an infection it's often caused by a bacteria can also be caused by a virus an infection is jeanna in general anything entering you and taking advantage of your body to kind of replicate itself and in the process making you sick but bacterial infections let me write that down bacterial infections and this whole perception of bacteria being a bad thing is probably a good reason why almost any soap you see now says antibacterial on it anti bacterial because the makers of the soap know that in just in conventional thinking bacteria is viewed as a negative thing and you're like okay Sal I know where you're going with this and you know bacteria isn't all bad there are some good traits of bacteria good for example I can make I could stick some yogurt in some or I could stick some bacteria and some milk and it'll help produce some yogurt yogurt sometimes spelled yogurt yogurt you know and that's that's obviously a good thing it's a delicious thing to eat you say well I know I have bacteria in my gut and my gut helps me digest food and these are all true but you're like look you know what on balance I still think back is a bad thing and just so you know I'm not going to take sides on that debate as I tend to avoid taking sides on debates in these science videos maybe I'll do a whole playlist where all where I do nothing but take sides on debates but here I won't take any size on that but I'll just point out that you are to a large degree made up of bacteria it's not just your gut it's not just the gut or the yogurt you might eat or the plaque on your teeth which is caused by bacteria it's this kind of film that's created by bacteria that eventually causes cavities and whatever else and it's not just the pimples on your face the pimples on your face bacteria actually represents a majority of the I guess you call of the cells on your body so for every forever and this is a kind of an astounding fact for every one cell on the human body every one human cell one human cell so these are all cells that you know all have your DNA in them and they all have nucleuses and i'll talk about in a second you have 20 bacteria 20 bacteria now your response there says okay that's fair enough but these bacteria must be much smaller than the human cell so it must be a very small fraction of my mass and you're right it's not like we're mostly bacteria by mass although we are mostly bacteria by actual cells but even if you were take out all of the water in your body then by mass bacteria is going to be roughly 10% of your mass of your mass so I weigh about 150 pounds I've got 15 pounds of bacteria walking around with me so you know one we always kind of think ourselves is like you know the bacteria is riding on us but to a large degree we're kind of in symbiosis we're kind of two creatures are not just two creatures two types of creatures living together because I don't have just one type of bacteria on we have thousands of types of bacteria on me there's a huge amount of diversity and we're just scratching the surface in terms of the the number and types and diversity of bacteria that exist so I've talked a lot about bacteria and hopefully this fact right here will make you realize that they're super important to just our everyday existence and just to make you know make sure we understand the magnitude of this in a previous video and I and I look this up again we have on the order of we have on the order of 10 to 100 trillion cells human cells trillion cells so for every one of these we have 20 bacteria we're talking we're talking about having on the order of 200 to 2,000 trillion bacteria on us at any time trillion bacteria and I'm a hygienic person I'm no you know I take showers daily and that's even me it's not like you can somehow eliminate them and even more it's not like you even want to eliminate them but that's fair enough you're probably asking okay Sal I'm convinced that bacteria are important what what do they actually look like and there are these small unicellular organisms may that's my bacteria right there and they're different from the cells that make up us and when I say us I'll throw in all plants animals and fungus --is fungi and the big difference or the one that people noticed first is that all of the Eukarya you Karia which includes plants animals and fungi all of their DNA is and can is inside of a nucleus a cellular nucleus so that's the nucleus right their nucleus and all of our DNA it's normally in its chromatin form it's all just you know spread around something like that on in bacteria which are you know what people originally just classified on whether or not you have a nucleus in bacteria there is no membrane surrounding the DNA so what they have is just a big a big bundle of DNA so they just have this big bundle of DNA it's sometimes in a loop all in one circle called a nucleoid nucleoid nucleoid now whenever we you know we look at something we say oh we have this thing it doesn't there's this assumption that somehow we're superior or we're more advanced advanced beings but the reality is is that bacteria have infiltrated far more ecosystems and every part of the planet then you care you have and there's far more diversity in bacteria in bacteria than there is in Eukarya so when you really think about it these are the more successful successful organisms if we were to have you know a if a if a comet were to hit the earth god forbid the the organisms more likely to survive are going to be the bacteria than the Eukarya than the ones with with the the the large not always larger but the organisms that do have this nucleus and have membrane bound organelles like mitochondria and all of that we'll talk more about in the future bacteria for the most part just big bags of cytoplasm they have their DNA there they do have ribosomes because they need to have to they have to code for proteins just like the rest of us do and some of those proteins they'll make some for from bacteria they'll make these flagella which are tails that allow them to move around that allow them to move around they also have these things called pili pili is plural for pylus or p lists so these pili and we'll see in a second the pili are kind of the how the bacteria are able to do one form of introducing genetic variation into their into their into their populations but a big and actually I'll take a little side note here I'm pointing out bacteria is not having cell wall there's actually another class that used to be categorized as type of a bacteria and they're called archaea and I should give them a little bit of justice they're always kind of the stepchild RRK archaea they used to be called archaea bacteria but now people realize they've actually looked at the DNA because when they've originally looked at these they said okay these guys also have no nucleus and a bunch of DNA running around these must be a form of bacteria but now that we've actually been able to look into the DNA of the things we've seen that they're actually quite different but all of these both of these both bacteria and archaea are considered prokaryotes pro carry oats and this just means that no no nucleus no nucleus and more general I mean this is what most people refer to but more generally they don't have these membrane bound organelles that our cells have now the next question you might say is well how does these bacteria reproduce and for the most part they do something not not completely different from mitosis although I want to call it mitosis we call it binary fission binary fission binary fission I'm not going to go into the deep mechanism here but the idea is fairly simple I have a bacteria right here it replicates its DNA so it starts you know it'll have to these nuclei oh dear and then the cytoplasm essentially splits or you know you can it's kind of a form of cleavage right there it splits and then you have two of them you have two of them then and then each of them they can code for the proteins necessary to produce all of their extra appendages the flagellum which is this long tail like thing that can help it move and it's actually fascinating because it's operating at such a small scale but you can still kind of get these this motor movement going on even at this very very small scale using very primitive I want to say primitive because that's making a value judgment on these things but using you know that these flagellum are on the order of several nanometers on the order of tens of nanometers wide so I mean it's not this you know you don't have a lot of atoms to deal with but you're still able to get this kind of wave-like motion that can move the bacteria around now you're saying hey Sal on that first video on on evolution you told me that you know bacteria we see evolution every day and bacteria is one example you know when we use antibiotics they we think it'll help eliminate bacteria but that one bacteria that has some type of resistance it'll survive and so it is more fit how do these guys get variation well the one way and this is a way everything can get variation is they can get mutations mutations and bacteria replicate so quickly they reproduce so quickly that even if even if you know you have a mutation is one in every thousand times by the time you have a million bacteria you'll have a thousand mutations so you have mutations but they also have this form I don't want to call it sexual reproduction because it's not sexual reproduction they don't form gametes and the gametes don't fertilize each other and then produce a zygote but two bacteria two bacteria can get near each other near each other and then one of their penises penises I'll do that right here so the P lists are these little structures on the side of the bacteria they're these little tubes really one of the penises can connect from one bacteria to another and then essentially you have a mixing of what's what's inside one bacteria with another so let me draw their nucleoid they're nucleoid and then they have these other pieces of just DNA that hangs out called plasmids these are just circular pieces of DNA plasmids maybe this guy's got this extra neat plasmid he got it from someplace and it's making him able to do things that this guy couldn't do maybe maybe this is the R plasmid which is known for making a bacteria resistant to a lot of antibiotics and what happens is is that bacteria is actually there's mechanisms where the bacteria know that hey this guy doesn't have the our plasmid and we're just beginning to understand how it actually works but this will actually replicate itself and give this guy a version of the our plasmid you could also have these things transposon x' and I should make a whole video on this because we have transposon stew but there's parts of DNA that can jump from one part of a fragment of DNA to another and these can also end up in the other one so what you have is kind of it's not formal sexual reproduction but what you just sensually has as a connection and these bacteria are just constantly swapping DNA with each other and DNA is jumping back and forth so you can imagine that all sorts of combinations of DNA happened even in within a what you used to call one bacterial species and very quickly can turn to multiple species and become resistant to different things if this makes it resistant to an antibiotic then it can kind of spread the information to produce those resistant proteins or whatever to the other bacteria so this is kind of a form of introducing variation and so when you when you transfer stuff via this pilis or the plural is pili this is called conjugation bacterial conjugation kanjou and Gatien now the last thing I want to talk about because this is something that you've heard a lot about are antibiotics antibiotics a lot of people they get sick the first thing they want to get is an antibiotic anti biotic and an antibiotic is just a whole class of chemicals and compounds some of them naturally derive some of them not that kill back kill kill bacteria so now if someone has is gone undergoing a surgery and there's you know they get a cut instead of them having to worry about getting the infections they'll take some antibiotics to prevent the the bacteria from growing on them but the question is where does this you know how is this how is this discovered or where does it come from and actually came from it came from Alexander Fleming let me write him down very important because the discovery of antibiotics is in my opinion the most important discovery in medicine so far so Alexander Alexander Fleming he was studying I think it was Staphylococcus I forget which bacteria was but it was in a petri dish he was in a petri dish let me draw a petri dish it's a little circle there's some nutrients that the bacteria can grow on so let's say the bacteria you know it's it's growing on this petri dish and he went out and he came back into the room and he saw that some mold some some fungus had had grown on this kind of bluish greenish fungus had grown on the center of his petri dish on the center of his petri dish and the bacteria there was kind of the space around and the bacteria couldn't get close to it and this mold this this fungus was called this Penicillium Penicillium fungus he was able to figure that out he took a sample of this and then he cultured it which means letting it grow and then seeing what it is this was Penicillium and he figured out that gee this this longus must have something some chemical that it's emitting that's essentially killing the bacteria around it it's not allowing the bacteria to get near it and so that led to the discovery of penicillin penicillin I see Panna penicillin and now that he discussed was in the late 20s 1920s now once you know by time World War two came around now people had gunshot wounds and had to get things amputated whatnot but for the first time they could actually give people antibiotics and not worry about or they probably still worried about it but didn't have to worry about this thing as much as they did before and now you know if you have a bacteria if you have tuberculosis or Lyme disease or anything the key the the the treatment it all involves taking antibiotics and there are many many more types of antibiotics now coming from many many more different sources but the general idea is the same you want to kill bacteria although you don't want to kill all bacteria because some of its good in fact we are made up of a lot of bacteria there's even there's even I don't know if I even mentioned this early in the video there's bacteria on our skin that helps take up oil and moisturizes and make our skin nice and supple so you know the way you think about you could view them as negative or you could view them as positive or you could do them is something in between but the really amazing thing at least in my mind is that we're living in symbiosis with them I remember I saw a Star Trek episode once where you had these you had these people you had these people and you know there was some alien race Jean Jean Luc Picard had had you know they ran into them they looked very humanoid like that but it turns out let me draw this human that they had these little bugs in their brain stem so they had these big insects in their brain stem and these insects started infecting the crew of the enterprise and making people and they were controlling their brains and making them act weird and whatever not and this seemed like a very bizarre alien concept right of some creepy crawly living in us and in affecting our brains and infecting us in some ways but if you really think about it we are doing this and it's not just with one little bug it's with it's with on the order of trillions hundreds of trillions of bugs are with us every day and they make us us I mean I'm here according videos with along with or maybe I should even say the bacteria is recording videos or it's maybe partially responsible for controlling bacteria and as if it's known that the bacteria can even affect our mental state there's a bun a whole bunch of research now that certain types of bacteria can cause schizophrenia actually syphilis does bacteria can cause depression a Lyme disease Lyme disease it's known that when you go into later phases of Lyme disease it can cause it can affect the mental condition of the person who's who has the infection so it affects every part of who we are I mean it would be hard to even talk of being a human being without that the 10% of our mass or the you know two thousand trillion cells of that or two thousand trillion bacteria that really make us us
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