What is the structure of bacteria?

Bacteria are unicellular organisms with a simple structure. The cell is completely surrounded by a cell wall made up of a special protein called peptidoglycan. The cell wall is a rigid structure of uniform thickness and is responsible for giving the cell its distinctive shape – spherical, rod-shaped, spiral, or comma shaped. Some bacteria have an additional protective layer – a hard outer membrane called the capsule. Most but not all bacteria have one or more flagella attached to the outermost layer. When present, the flagella functions as an organ of locomotion. In some bacteria, it helps the cell attach to the host cell.