Hi. In this video, I'm going to be talking about the history of cell biology. So, before there was any kind of study of cell biology, we actually had to discover cells. This was really limited by the fact that cells cannot be seen with the naked eye. Instead, we have to use instruments or specialized tools in order to be able to even look at them, much less study them. I'm sure you're familiar with these tools through your biology and chemistry classes that you've taken in the past. We use microscopes to magnify an object, and that way, we can use them to visualize and study cells.
Before microscopes were invented, humankind had to invent the lens, and these lenses are the types that were used in eyeglasses and are now today used in cameras and computers. Lenses were originally invented in the 13th century. By the mid-1600s, advances in lens technology had increased enough so that people, especially scientists, could begin making homemade microscopes. Here is an example of what a homemade microscope would have looked like. This is just a drawing from the 1600s, and you can see that it's fairly simple. It doesn't necessarily look anything like a microscope that you've seen in the past, but this is what they looked like in the 1600s.
This is the type of microscope that a person we're going to talk about, whose name is Robert Hooke, used. He was the first person to propose the idea of cells. He didn't seek out to determine whether cells existed. That wasn't really what he was concerned with. His question, and the reason he was really studying this at the time, was because he wanted to answer the question: Why are corks so good at holding air in a bottle? This seemingly simple question actually led to the incredible idea of cells and cell biology.
What Hooke did is he took a piece of cork, cut it off, and put it under his homemade microscope, which at the time had around 30x magnification, which is really small compared to some fancy cameras and computers today. What he was able to see, you can actually see down here, this is a drawing that Hooke did, and you can see that he saw these compartments that the cork had in them, and he named them 'cells' based off the cells that monks lived in at the time. What he was seeing was dead plant tissue; he was seeing cell walls. He wasn't seeing living cells, but he gave them their name and set the groundwork for further inquiry into what these compartments were and how we could study them more.
Following this drawing and following his idea of cells, Anton van Leeuwenhoek was the first to visualize live cells. This was very crucial to the discovery of cells because now we knew that they were living and could move. His homemade microscope actually had the ability to magnify up to 300x, which is 10 times more than Hooke's microscope, and that's what allowed him to visualize live cells versus dead ones. What he did, like anyone with curiosity, as I'm sure we've all done as kids, is he just took whatever was around him and looked at it under his microscope.
He took pond water, blood, and sperm and just stuck it under his microscope and said, "Okay. What's there?" What he saw were live cells that made up blood, some of the organisms in pond water, and sperm. He was so excited and wrote letters to the Royal Society, which at the time was this big scientific organization that sort of controlled the scientific knowledge at the time. He said, "Look what I've seen. I've seen these live cells; they're kind of amazing." He sent Hooke, Robert Hooke, to confirm his observations, because they were a little skeptical at the time. Hooke came and saw these live cells under his microscope and wrote back to the Royal Society saying, "Yes, this is what happened." Here, you can see there's just a drawing of William Hoag's blood cells of what he saw when he saw blood. Let's now move on to the next concept.
