Bacteria are single celled, prokaryotic organisms that are capable of living in extreme conditions and have cell walls composed of peptidoglycan. They are either heterotrophic or autotrophic and can be harmless or cause disease (Mycobacterium tuberculosis).

Bacteria

Bacteria is a very diverse domain, characterized by their prokaryotic cells and lack of ether linkages, with membranes made of phospholipid bilayers.

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Examples of Domains

A prokaryotic cell is a unicellular organism that lacks a defined nucleus and membrane bound organelles. As a result, many catabolic processes occur within the cytosol. 

Prokaryotic cell

Woese C, Kandler O, Wheelis M (1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya". Proc Natl Acad Sci USA. 87 (12): 4576–9. Bibcode:1990PNAS...87.4576W. doi:10.1073/pnas.87.12.4576. PMC 54159. PMID 2112744. Retrieved 11 February 2010.

Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya

The domain Eukarya contains members called eukaryotes, defined by their eukaryotic cells.

Eukarya 

Bacteria (domain)

Photosynthesis is the process of using the sun's light as energy and converting it to chemical energy to fix gaseous carbon dioxide and create sugars such as glucose. The first organisms with the capability to photosynthesize stemmed from prokaryotes 3.8 billion years ago. What is required for photosynthesis include a light source, carbon, electron donor, and pigments to harvest energy.

Photosynthesis

Archaea are single-cellular organisms that do not contain nuclei. Archaea different from bacteria because archaeal membranes and cell walls are structurally different.

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