By the end of this section, you will be able to:
• Describe the evolutionary history of prokaryotes
• Describe the basic structure of a typical prokaryote
• Identify bacterial diseases that caused historically important plagues and epidemics
• Describe the uses of prokaryotes in food processing and bioremediation
Prokaryotes are present everywhere. They cover every imaginable surface where there is sufficient moisture, and they live on and inside of other living things. There are more prokaryotes inside and on the exterior of the human body than there are human cells in the body. Some prokaryotes thrive in environments that are inhospitable for most other living things. Prokaryotes recycle nutrients—essential substances (such as carbon and nitrogen)—and they drive the evolution of new ecosystems, some of which are natural while others are man-made. Prokaryotes have been on Earth since long before multicellular life appeared.