In this video, we're going to begin our lesson on microscopes. A microscope, as its name implies with the root micro (meaning small) and the root scope (an object we look through), is an optical instrument that can be used to visualize microscopically small objects, such as cells, which are the smallest units of life.
There are two main types of microscopes that are commonly used and that you should be familiar with. First, the light microscopes, which, as the name implies, use visible light to magnify small objects and make them appear larger. These microscopes are very common and prevalent, and they are the ones you are most likely to use in any typical biology lab. Second, the electron microscopes, which, unlike light microscopes, do not use visible light. Instead, as their name suggests, they use electrons to provide a significantly higher magnification of small objects, allowing us to see even smaller items than what the light microscope can reveal. These are more advanced, complex, and expensive tools compared to light microscopes, and thus, it is less likely that you will use an electron microscope unless you are in certain labs where they are available.
Now, if we look at the image displayed below, it shows the ranges of the human eye, light microscopes, and electron microscopes. This scale is organized from left to right, with the smallest objects on the far left and the largest objects on the far right. The largest object shown here is a human being, and the smallest is the atom. Atoms are measured in units called angstroms, which are extremely small units we will discuss more later in our course. Notice that the human eye has a cut-off in terms of how small of objects it can see, not being capable of seeing most plant and animal cells, as well as most bacteria and archaea.
The range of the light microscope is indicated by a blue bar which extends to visualize most plant and animal cells as well as most bacteria and archaea. However, it has a cut off and cannot visualize smaller objects like viruses, molecules, and atoms. To see these, we need the more powerful electron microscope, represented by an orange bar. This microscope allows visualization of very small objects, including viruses, proteins, lipids, and atoms, being very effective even at the high magnification needed for the smallest discernible items. It's important to note from this image that plant and animal cells (eukaryotic cells with a nucleus) are larger than most bacteria and archaea (prokaryotic cells).
This concludes our brief introduction to microscopes, and we'll be able to apply these concepts as we move forward and learn more as well. I'll see you all in our next video.
