What are the defining characteristics of bacteria?

Bacteria are defined as prokaryotic organisms, meaning they lack a true nucleus and membrane-bound organelles. This characteristic distinguishes them from eukaryotic organisms, which have cells with distinct nuclei. Bacteria typically contain a single, circular chromosome that carries their genetic information. This is different from eukaryotes, which usually possess multiple linear chromosomes.

Furthermore, most bacteria have a cell wall composed of peptidoglycan, a complex carbohydrate that provides structural support and protects the cell membrane. The presence of a cell wall is a crucial feature for the classification of bacteria and contributes to their various shapes and the distinction between different bacterial groups.

In summary, the defining characteristics of bacteria include being prokaryotic, typically having one circular chromosome, and possessing a cell wall, which together provide a framework for understanding their biology and classification within the broader scope of life forms.