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. And so organisms can be classified into 2 groups based on their energy source. So the first group are going to be the phototrophs. Phototrophs are organisms that obtain their energy directly from sunlight. That's because the root "photo" means light. Now chemotrophs, on the other hand, as their name somewhat implies, are going to be organisms that obtain their energy directly from chemical compounds that they must obtain from their environments.
If we take a look at our image below, on the left-hand side, we're showing you 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 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. 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 source 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.