Final answer:
The statement about the peptidoglycan layer being made of alternating NAG and NAM glycans is true. Peptidoglycan provides structural strength to bacteria cell walls and is a distinguishing feature between Gram-positive and Gram-negative bacteria.
Step-by-step explanation:
The statement that the peptidoglycan layer of bacteria is made of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) glycans is true. The peptidoglycan structure is critical for maintaining the cell shape and protecting against osmotic pressure. It is composed of long chains of NAG and NAM, which are connected by peptide bridges. These peptide bridges give the cell wall its tensile strength. Both Gram-positive and Gram-negative bacteria contain peptidoglycan in their cell walls, with the crucial difference being in the thickness and the presence of additional structures like the outer membrane in Gram-negative bacteria. Gram-positive bacteria have a thick peptidoglycan layer anchored to the cell membrane by lipoteichoic acid, while Gram-negative bacteria also contain peptidoglycan, but their peptidoglycan layer is relatively thin and is located underneath an outer membrane composed of lipopolysaccharides and lipoproteins.