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Video transcript

to us modern folk we tend to take for granted the existence of cells and the idea that all living things are made up of cells that we as human beings as living organisms were made up of many many many cells and the estimates of the cells in the human body are on the order of 37 37 trillion trillion cells but if we were to rewind even 400 years ago to the 1600s this wasn't so obvious and that's because people really didn't have the tools to make direct observations of cells they didn't know that these cells were around they didn't know that things even like unicellular organisms even existed but all of that began to change with Robert Hooke Robert Hooke was able to leverage primitive microscope and this is a picture of his microscope when you see this you you appreciate how at least relative to what we have today how primitive it was he had lenses here that would provide some magnification but he had to use this right over here this is a flame and we're able to channel that light so that it gets reflected over whatever he's observing and in 1665 he publishes the micrographia I'm probably not producing it I'm probably not pronouncing it right so this is 1665 Robert Hooke publishes this and in this he describes and he draws a lot of his observations using his microscope and he has some fascinating drawings he was actually quite a good artist where he's able to draw pictures of his observations of things like lice and and fleas but it's not just lice and fleas that he's able to observe he actually takes a look at some cork some corks or what what he just sees is cork and when he makes that observation he says hey look you know they're these little they're these little squares over here and this kind of seems to be somehow kind of a basic unit of of this of this cork and he says well this kind of reminds me of these little these little rooms that monks live in and spend their time in which we call cells so he calls these cells and that's where the word comes from he calls themselves and micrographia that is a cell now unfortunately for us he was a great artist in in or he was really good at drawing things and he drew a lot in his micrographia but we don't have any pictures robert hooke anymore it's a fascinating story most theories are that actually was Isaac Newton burned the only the only original of painting that we have of Robert Hooke and that's another intriguing story that we can talk about at a future date but what Robert Hooke he coined these things cells but he was looking at dead tissue and actually he was looking at the remnants of cells and what he saw was really just the cell wall the cell wall remnants he wasn't actually able to observe directly living cells and he didn't have enough to go on to think hey maybe this is a building block of all life and maybe cells themselves reproduce and and all cells come from other cells and that doesn't start to get developed until we get further on into history you go a few years later we get to Antony van Leeuwenhoek Leuven Hooke I know not probably pronouncing it right but he was a Dutch lens crafter and he was inspired by Hookes work he says well hey I can craft lenses maybe I can use that to make better microscopes and make better observations and he was able to do that and doing that he was able to directly observe living cells and living unicellular organisms so he was able to directly observe sperm and say we did this thing this thing is it looks like it's alive he was able to observe he was able to directly observe protists so these unicellular eukaryotic they have cell walls these things that looked like unicellular animals and he called them actually animal cules and molecules saying hey look there these look like these like little these little mini animals going on here and so he started said well maybe this is some form of a basis of life or at least he's trying to say that these at this very small scale you actually have life but a fully modern theory of the cell doesn't really start to emerge until we get another 100 150 years into the future and we get into the early 1800s so if you go if we fast-forward to the 1830s these two gentlemen matthias schleiden and theodor schwann come into the picture and they're the ones that start laying the foundation of what we could call modern cell theory so modern modern cell theory and using their observations and kind of what they were able to deduce they said eh maybe maybe maybe all living things all life is composed of one or more cells is composed of one or more cells one or more cells and today we kind of take this for granted this wasn't obvious it wasn't obvious at all things that this is somehow a building block for life one or more one or more cells and then following that if all life is composed of one or more cells you can also say that a cell is the basic unit of life cell is basic basic unit of life and these are strong statements that all life if you were to get down small enough you're going to come you're going to going to come to cells living cells that make up that life now this isn't our full complete cell theory and both of these gentlemen they knew that cells could come from other cells they were able to observe cells reproducing but they were but it still was an open question hey maybe some cells come from other cells while others maybe they sometimes somehow get spontaneously created if you have the right elements in the right amount of conditions maybe they somehow just emerge out of nothing and it wasn't until this kind of third tenant of modern says it wasn't until the mid eighteen 1800s that we get our third tenet of modern cell theory that gets established and this is this idea that all cells all cells come from other cells all cells from from other cells and the real father of this idea the one that really established this is this gentleman right here Robert remac now sometimes the credit for this goes to Rudolf Virchow or Burke how right over here but it turns out that he plagiarized remax work he plagiarized remax work right over here so it's really remac who should who deserves the bulk of the credit for this tenant that all cells come from other cells and once again he wasn't the first person to say hey we observe that some cells come from other cells would say no this is a this is a fundamental thing all cells this is how they actually come about they aren't just somehow spontaneously emerge now whenever even in today's world people see this lasting all cells come from other cells there's a natural question well there must have been a a first cell or initial set of protocells and people aren't 100% short but when we look back at the evolution of life on earth we think the first cells emerged about three and a half billion years ago and we're not 100% sure about how they emerge but there are some theories for example we have videos on phospholipids and it turns out that phospholipids naturally naturally form naturally form by layers so phospholipids naturally form by layers and they can actually form a spherical they can form spherical membranes that have phospholipid bilayers so that kind of gets you a start so that can spontaneously form and there's also theories that maybe the information the machinery of cells may be there their ancestry for about three and a half billion or longer ago then it might have been maybe it was self-replicating RNA molecules where maybe it was somehow self-replicating proteins that over time over very large large timescales were able to start start replicating themselves have more sophisticated machinery the the ones that had kind of we're approaching our modern cells were able to reproduce more we're able to take advantage of kind of more of the energy the resources in an environment so that we eventually get with our modern cells but this is a fascinating question and is still an area of research
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