Some bacteria are autotrophs; these are bacteria
that obtain carbon from carbon dioxide. They receive their energy
from different sources. Organisms that use light to obtain their
energy are known as Photoautotrophs (blue-green algae). Photosynthesis
is the process by which light energy is converted to chemical energy in
the form of glucose. Chemoautotrophs are bacteria that receive their
energy from inorganic compounds like hydrogen sulfide and use energy to
run the cell’s activities. The rest of the bacteria are heterotrophs,
organisms that obtain carbon by ingesting organic molecules from decaying
organisms or by living on or in another organism known as a host.
Quick Fact: With the exception of the ribosomes, prokaryotes lack organelles.
To get energy from molecules such as sugars, bacteria must use fermentation or cellular respiration. These are processes that use the energy in the molecules to make adenosine triphosphate, known as ATP. This is used for growth, movement, temperature regulation, and many other processes that require energy. Fermentation, the process most bacteria use, mostly take place in an anaerobic environment. Bacteria produces unique byproducts like alcohol, carbon dioxide, lactic acid, formic acid and acetic acid. Some species of bacteria go through the process of cellular respiration. This is a more complex process that doesn’t need oxygen, and the energy of the organic molecules is more efficient in the creation of ATP. Carbon dioxide and water are the byproducts most usually produced.