Acid phosphatase is an acidic hydrolase specifically localized within lysosomes (optimal pH $\sim 4.5-5.0$), making it the standard diagnostic marker enzyme for lysosomes in subcellular fractionation.

Naturally occurring standard amino acids incorporated into ribosomal protein synthesis in mammals and other living organisms are exclusively $\alpha$-L-amino acids (L-stereoisomers with amino group attached to the alpha carbon).

Na+/K+ ATPase is an integral membrane P-type ion pump that actively exports $3\text{ Na}^+$ and imports $2\text{ K}^+$ per ATP hydrolyzed, serving as the classic biochemical marker enzyme for the plasma membrane.

The rigid bacterial cell wall is composed of peptidoglycan (murein), a mesh-like polymer of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) residues cross-linked by short peptide bridges.

S.J. Singer and G.L. Nicolson proposed the widely accepted Fluid Mosaic Model of biological membranes in 1972, describing membranes as a two-dimensional viscous lipid bilayer with embedded and peripheral globular proteins.