Bacterial Outer Cell Structures

Plasma membrane

• phospholipid bilayer

• embedded proteins which facilitate cell signaling and transport

• protects the cell from the extracellular environment by regulating transport of substances and molecules

Cell wall

• prokaryotes

• protects the cell from the pressure exerted by much higher concentrations of proteins and molecules inside the cell compared to extracellular environment

• shapes bacteria

gram-positive cell wall

• thick layer of peptidoglycan 

gram-negative cell wall

• think peptidoglycan layer 

• outer membrane 

Capsule

• bacteria

• surrounds cell wall

• helps adhere to surfaces

• relatively impermeable

• made of polysaccharides and sometimes proteins

• protects bacteria from killing or digestion and desiccation