Bacteria

Definition

Bacteria are single-celled, prokaryotic microorganisms that lack a nucleus and membrane-bound organelles. They can be found in nearly every habitat on Earth and have diverse metabolic capabilities.

5 Must Know Facts For Your Next Test

1. Bacteria are classified into various groups based on their shape, such as cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped).
2. Proteobacteria is a major phylum of Gram-negative bacteria that includes a wide variety of pathogens, such as Escherichia coli and Salmonella.
3. Bacteria reproduce primarily through binary fission, a process where a single cell divides into two identical daughter cells.
4. Many bacteria form symbiotic relationships with other organisms, including humans; some are beneficial while others can cause diseases.
5. Bacterial habitats range from extreme environments like hot springs and deep-sea vents to more common places like soil, water, and the human gut.

Review Questions

• What are the main shapes used to classify bacteria?
• Name two pathogenic bacteria that belong to the Proteobacteria phylum.
• Describe the process by which bacteria typically reproduce.

Related terms

Prokaryote: An organism that lacks a distinct nucleus and membrane-bound organelles.

Microbiome:

The collection of microorganisms living in a particular environment, such as the human body.

Symbiosis:

A close and long-term biological interaction between two different biological organisms.