39 diagram of a bacterium
Bacteria. When Carl Woese first set forth the three-domain classification of life, he proposed the names "Archaebacteria" and "Eubacteria" for the two prokaryotic domains. Euzeby, J.P. "List of Bacterial Names with Standing in Nomenclature: a folder available on the Internet." Bacterial reproduction commonly occurs by a kind of cell division called binary fission. This type of asexual reproduction produces identical cells. This is a colored transmission electron micrograph (TEM) of an E. coli bacterium in the early stages of binary fission. Credit: CNRI / Getty Images. Size of Bacterial Cell. The average diameter of spherical bacteria is 0.5-2.0 µm. The three basic bacterial shapes are coccus (spherical), bacillus (rod-shaped), and spiral (twisted), however pleomorphic bacteria can assume several shapes. Diagram of a bacterium