Final answer:
The bacterial cell wall is essential for structural support, maintaining cell shape, and protection against osmotic pressure changes. It is mainly composed of peptidoglycan, which is targeted by certain antibiotics. Bacteria can be classified into Gram-positive and Gram-negative based on cell wall composition and structure.
Step-by-step explanation:
Function and Composition of Bacterial Cell Wall
The primary function of the cell wall in bacteria is to provide structural support and shape to the cell. It also protects the bacterium from osmotic pressure changes that can occur in different environmental solute concentrations.
Importantly, the cell wall is a critical component preventing bacterial cells from swelling and bursting in hypotonic environments (low solute concentrations outside the cell compared to the inside).
The composition of a bacterial cell wall includes peptidoglycan, which is a complex polymer made up of sugars and amino acids. This substance forms a mesh-like layer outside the bacterial cell membrane.
Notably, peptidoglycan contains unusual amino acids, such as D-glutamic acid and D-alanine, which are not frequently found in proteins that have only L-amino acids. This unique composition is targeted by antibiotics like penicillin, which inhibit cell wall synthesis, leading to bacterial death in hypotonic conditions.
Bacteria are generally classified as either Gram-positive or Gram-negative, based on their cell wall structure and composition.
Gram-positive bacteria have a thick peptidoglycan layer, often reinforced with teichoic acids, whereas Gram-negative bacteria have a thinner peptidoglycan layer and an additional outer envelope containing lipopolysaccharides and lipoproteins.