In this video, we're going to introduce microscopes. A microscope, as its name implies, is really just an optical scope used to visualize microscopically small objects, such as cells, for instance. The root "micro" means small, and scopes are objects we look through with our eyes. There are two main types of microscopes that are commonly used that you all should know about. We've got these two microscopes numbered down below, number 1 and number 2. The first type of microscope is the light microscope, which uses light to magnify small objects and make those small objects appear larger. The second type is the electron microscope, which is much more complex, advanced, and a much more powerful tool than the light microscope. Electron microscopes use electrons for an even higher magnification of small objects.
Let's take a look at our example down below at the ranges of the human eye, light microscopes, and electron microscopes. When we look at this image, notice that it has a scale here with all these numbers showing different units of length. Here for perspective, humans fall on the right-hand side and atoms fall on the far left-hand side. The left side represents things that are really small, and the right side represents things that are much larger. As we go from left to right, things are getting larger. On the bottom in green, we have the range of the human eye. Our eyes can visualize very large things, going much beyond the size of humans. But in terms of small, there is a cutoff, and if we want to visualize things like most plant and animal cells and most bacteria and archaea, then we're going to need to utilize microscopes.
Notice here in blue the range of the light microscope. The light microscope is used to visualize things such as most plant and animal cells, as well as most bacteria and archaea. However, the light microscope also has a cutoff and isn't powerful enough to visualize viruses, for the most part. To visualize things that are even smaller, we need another type of microscope, defined as the electron microscope. Electron microscopes are much more powerful tools and can be used to visualize most plant and animal cells, most bacteria and archaea, viruses, molecules such as proteins and lipids, even smaller molecules such as water, and atoms themselves. Electron microscopes are very expensive tools, whereas light microscopes are still helpful for magnifying lots of small cells but are less expensive.
Most of you, if you've taken a biology lab before, may have even used a light microscope in the past. However, the chances that you would have used an electron microscope are very slim due to their high cost. You can see here that frog eggs, which are cells, can be visualized with the human eye. However, most plant and animal cells and most bacteria and archaea fall outside the range of the human eye; they're just too small for us to see. Ants, which you might think of as very small, are incredibly large in perspective to things like atoms. Another major takeaway is that most plant and animal cells, which are eukaryotic cells, are significantly larger than most bacteria and archaea, which are prokaryotic cells. This concludes our introduction to microscopes, and we'll be able to talk a bit more about electron microscopes in our next lesson video. I'll see you all there.
