In this video, we're going to be reviewing the nutritional growth factors of microbes by completing the table that you see here. And so notice that we have this table organized by the three nutritional factors: energy source, electron source, and carbon source. Now, in terms of the energy source, scientists organize microorganisms either as phototrophs or chemotrophs. Phototrophs are organisms that obtain their energy directly from sunlight, whereas chemotrophs are going to be obtaining their energy from chemical compounds.
Now, in terms of the electron source, scientists organize microorganisms either as lithotrophs or organotrophs. Lithotrophs are going to be organisms that supply their electron transport chain or ETC with electrons from reduced inorganic molecules, which are molecules that do not contain carbon and hydrogen, such as, for example, water. Now, organotrophs, on the other hand, are going to be organisms that supply their electron transport chain or ETC with electrons from organic molecules or molecules that contain carbon and hydrogen, such as, for example, glucose.
Now, in terms of the carbon source, scientists will organize organisms either as autotrophs or heterotrophs. Autotrophs are going to be fixing inorganic carbon dioxide to make their own molecules of food and supply the cell with carbon. Heterotrophs, on the other hand, are going to consume premade organic molecules, rather than inorganic molecules, to supply the cell with carbon.
And so this here concludes our brief review of the nutritional factors of microbes, and we'll be able to get more practice and learn more as we move forward in our course. So, I'll see you all in our next video.