Prokaryotes come in a variety of simple shapes and often group together, forming chains or clusters. These characteristics, particularly the shape, are used to describe, classify, and identify microorganisms.
Most common bacteria are one of two shapes: spherical, called a coccus (plural: cocci); and cylindrical, called a rod (figure 3.20). A rod-shaped bacterium is sometimes called a bacillus (plural: bacilli). The descriptive term bacillus should not be confused with Bacillus, the name of a genus. While members of the genus Bacillus are rod-shaped, so are many other bacteria, including Escherichia coli.
Cells have a variety of other shapes. A rod-shaped bacterium that is so short that it can easily be mistaken for a coccus is
Chapter 3 Microscopy and Cell Structure
Was this article helpful?