How do prokaryotic cells get energy?

Prokaryotes get energy by performing chemical reactions within the cell. All organisms are able to do glycolysis, which splits a molecule of glucose in half and releases a little bit of energy in the form of ##ATP## (adenosine triphosphate).

Some prokaryotes are also capable of additional reactions that produce more energy, similar to what happens in the mitochondria of eukaryotes.

Aerobic prokaryotes contain the enzymes necessary to break down the pyruvate to carbon dioxide and produce a little more ATP, along with some electron carrier molecules like ##NADH## and ##FADH_2##. These electron carriers take the high-energy electrons to a series of membrane proteins to produce more ATP, very similar to what you see in the electron transport chain of cellular respiration in mitochondria.

Anaerobic prokaryotes either depend solely on the energy produced by glycolysis or are able to use other inorganic molecules (like ##H_2S##) as an energy source.