hey guys I want to welcome you back to a stem Stream tutorial we're gonna cover the cell theory today in this video and just about under eight minutes it's not too complicated of a topic but it's extremely important most people don't know that this theory is one of the most historic scientific universally accepted concepts and it essentially talks about how that living organisms on this planet are made up of cells and scientists were able to discover these cells using very early microscopes now I asked a student one time to describe the cell theory and he started talking about cell phones so I have to let you guys know unfortunately the cell theory has absolutely positively nothing to do with cell phones all right let's get to it a lot of good stuff to talk about hope you enjoy now a lot of students ask why is it important we learn about the cell theory now it's not only one of the most significant scientific discoveries ever we're talking about the discovery of the cell but it also represented a major major evolution in microscopes microscope technology that allowed scientists to really really visualize what they were hypothesizing in a laboratory now that they can actually see cells they could prove that they existed now these cells help define the characteristics of life but they did much more they laid the groundwork for much of modern biology that you learned today in class and in labs those include microbiology and cell biology as well as looking about common ancestry now common ancestry is a field that we still are analyzing today and there's a lot of companies that look at common ancestry like 23andme that you may know of it also contributed to the study of physiology and human disease now the cell theory actually dates back to the 17th century with Robert Hooke he was a man who worked for the Royal Society in England and he was a very prominent member of the Royal Society there was not too many pictures of him but here's a really nice one we found by Rita Greer painted in 2004 now as a member of the Royal Society he was a philosopher but he also did science experiments and at the time no one knew about cells so he was actually the first one to discover cells and he did so by using a very old-fashioned microscope that could only magnify 230 times magnification and he analyzed oak tree bark and found that the oak tree bark had these little tiny compartments that he coined as cells and the cell means small room and he couldn't see inside these cells he didn't know if they were alive but he was the first one to discover that they existed now shortly after Huck published his results a man by the name of Anton Van Leeuwen Hooke and I know I'm butchering that name completely I sincerely apologize but he was much more skilled at building microscopes and he was actually able to build one with 300 times the magnification which impressed the hell out of everyone he took protozoa and bacteria which he didn't know were protozoa and bacteria at the time but he he named them animal culés and he was able to see that they were modal and he reported to the Royal Society in the 1600s that because these were modal organisms and that represented a quality of life that these specimens were living organisms he's also credited for making the first observations of human red blood cells and very importantly sperm cells because he was able to observe that sperm and egg were fusing together to create a new generation of cells this was extremely important because it was the first evidence against spontaneous generation that cells were not just arising out of nowhere that they were coming from pre-existing cells that we know to be true today now following the work of hook and Lewin Hooke who were the ones who really solidified that cells existed the cell theory didn't really come into existence the theory itself until the mid 1800s so scientists at the time were were recognizing that cells existed but the theory about what these cells represented and what they stood for in terms of life was just beginning to surface so finally in the mid-1800s three German men by the name of Theodor Schwann matthias jakob sneed and rudolf virchow i know if i'm butchering those names again i apologize but these three men were finally able to come together with a large enough body of work and put together a concept known as the cell theory which is actually a group of concepts we'll go into right now but it is they are the ones who are credited for the cell theory building upon the world a previous scientist like hook and LuAnn hook alright let's bring in the drumroll now the cell theory is number one all living organisms are composed of one or more cells number two the cell is the most basic unit of life and number three all cells arise only from pre-existing cells now my question for you guys is which one of these components of the cell theory was the most controversial at the time and the answer to that is number three that all cells arise only from pre-existing cells and the reason that was so controversial is that it went against a very widely held belief that cells arose spontaneously and it was also very difficult to prove and it wasn't until experiments that were performed by Louis Pasteur where the scientific community was finally able to recognize that the theory of spontaneous generation was not correct and that cells arose only from pre-existing cells now most people don't think of the cell theory when they think of Louis Pasteur they immediately think of pasteurization which is a widely used commercial technique that we implement to help protect our food but he did indeed prove or at least in most people's minds convinced that patta that spontaneous generation was incorrect using swan-neck flask experiments where he boiled broth and proved that organisms must grow from pre-existing organisms now interestingly this topic of spontaneous generation is one that is still debated today amongst many prominent scientists in the scientific community now the beauty of the cell theory is that it's constantly evolving as we continue to make more and more advancements in science and technology now into the 21st century here are the few additions that the scientific community has made to the original cell theory and now into the modern cell theory the first addition really represents research that scientists are now able to do on multicellular organisms that they have now been able to truly appreciate that is billions and trillions of cells working together to allow a very complex organism to function the way that it does energy flow is some that scientists are looking at at a very molecular and micro level the cells contain a reddit area information we know this to be true of DNA which we will discuss in another video that's an incredible topic to talk about and also that cells and similar species have the same basic composition I hope you guys at the end of this video have a much better understanding of why the cell theory was so important and where it originated from it truly revolutionized the way the world thought about life and it opened the doors and paved the way for so much more scientific research that continues on to this day I just want to do a quick recap of what we discussed in the video that the first being the cells were first discovered and observed in the 17th century by Robert Hooke and Anton von Lewin hook it was their work and discovery that cells existed that paved the way for the cell theory to come about in the mid 1800s now the last component of the cell theory was very controversial at the time because it went directly against a widely held belief that cells arose spontaneously and did not come from pre-existing cells that Louis Pasteur was the man who helped disprove that with his experiments and this is actually a topic that's still being researched and debated today and finally the cell theory is continuing to evolve it's continuing to be talked about and researched on and that's the cool thing about sites that we're always gonna be moving forward and trying to advance science and technology for the benefits of humanity we appreciate you guys watching the video and we'll see you next time on stem string [Music]