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Gram-positive cell wall

Cartoon at the top presents gram positive cell wall. At the bottom is the cytoplasmic membrane composed of a lipid bilayer and interjected with membrane proteins. Above the cytoplasmic membrane is a thick peptidoglycan that appears like a large purple cube interspersed with tall light purple tubes labelled as Teichoic acid and touch the cytoplasmic membrane. A cartoon at the bottom shows alternating dark and light purple hexagons connected in lines representing alternating N-acetylmuramic acid, or N A M, and N-acetylglycosamine, or N A G. Connected to each N A M is a vertical line of four small orange circles labelled L - A l a, D - G l u, L - L y s, D - A l a. Horizontally connecting these vertical chains is a line of 5 small yellow circles labelled the pentaglycine cross-link.
Figure 1. Upper image. Gram-positive bacterial cell wall. Lower image. Peptidoglycan. (Purple subunits = sugars, Yellow/orange subunits = amino acids)


Cytoplasmic membrane: Surrounds the cytoplasm of both Gram-positive and Gram-negative bacteria.
It is similar to the one found in the mammalian cell membrane and consists mainly of proteins and lipids. It regulates the passage of molecules in and out of the bacteria.

Teichoic acids: Large amounts of teichoic acids are found in the peptidoglycan of Gram-positive bacteria.
The teichoic acids have many functions, such as protection from harmful substances, anchoring the peptidoglycan to the underlying plasma membrane, and help to stabilize the cell wall.

Peptidoglycan: The peptidoglycan of the Gram-positive cell wall is a thick (20-80 nm) mesh of repeating subunits containing sugars and amino acids.
The peptidoglycan provides rigidity and gives the bacteria its specific shape.
Some antibiotics, such as penicillin, inhibits the synthesis of peptidoglycan, causing the bacteria to die.