10

CHAPTER

151

The Prokaryotes:

Domains Archaea

and Bacteria

Mention the term bacteria and you probably think back to a time when you had
a bacterial infection. Some bacteria do cause disease, but other bacteria are ben-
eficial and live within our bodies, aiding in the digestion of food.
There are many different kinds of bacteria, all of which are prokaryotes.
Bacteria are divided into four divisions called phylabased on characteristics
of their cell wall. Each division is subdivided into sections according to other
characteristics, such as oxygen requirements, motility, shape, and Gram-stain
reaction. Each section is named based on these characteristics. Sections are fur-
ther subdivided into genera.
In this chapter, you’ll learn about major types of bacteria and their charac-
teristics.

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