ultrastructure of prokaryotic cells

• plasmid (not always present) : small circle of DNA
• Flagellum (not always present)  – hollow cylindrical thread-like structure that rotates to move the cell
• Pili (not always present) – thin, protein tubes allow bacteria to adhere to surfaces
• cytoplasm : provides shape to the cell
• Capsule (not always present) – slime layer on surface for protection and to prevent dehydration
• circular DNA : carries genetic information
• cell wall : contains peptidoglycan, a type of polysaccharide and polypeptide combined
• Mesosome – infolding of cell membrane (site of respiration)