In this video, we're going to talk more about the nutritional energy source of microorganisms, and how scientists can classify organisms either as phototrophs or as chemotrophs depending on their energy source. Organisms can be classified into two groups based on their energy source. So the first group is going to be the phototrophs. Phototrophs are organisms that obtain their energy directly from sunlight, which is because the root "photo" means light.
Now, chemotrophs, on the other hand, as their name somewhat implies, are organisms that obtain their energy directly from chemical compounds that they must obtain from their environments. If we take a look at our image down below, on the left-hand side over here, what we're showing you are phototrophs. Phototrophs obtain their energy from the light, the solar energy, sunlight. Notice here we have the sun and the solar energy radiating down here. And here we have our phototroph, which is going to be soaking up the sun and obtaining its energy directly from the sun.
Now, the chemotrophs on the other hand are going to be getting their energy directly from chemicals, chemical compounds. They have chemical energy such as glucose, for example, which is an example of chemical energy. Notice over here we have a chemotroph that's saying "look at all this energy," and it's coming from these chemical compounds rather than coming directly from sunlight. This here concludes our brief introduction to the energy sources of phototrophs and chemotrophs, and we'll be able to get some more practice applying these concepts as we move forward. So I'll see you all in our next video.