Summary:
- Bacteria can be classified by their shape, including bacilli (rods), cocci (spheres), and spirilli (spirals) The structure of a bacterial cell is distinctive from a eukaryotic cell because of features such as an outer cell wall, the circular DNA of the nucleoid, and the lack of membrane-bound organelles.
- Bacteria are surrounded by a cell wall consisting of peptidoglycan.
- The cell wall is so important that some antibiotics, such as penicillin, kill bacteria.