Portage Learning Microbiology Practice Exam 2025 - Free Microbiology Practice Questions and Study Guide

Peptidoglycan plays a crucial role in providing structural support to the bacterial cell wall. It is a polymer consisting of sugars and amino acids, forming a mesh-like layer that surrounds the bacterial cell membrane. This structure provides rigidity and shape to the cell, helping it withstand osmotic pressure and prevent lysis (bursting) in hypotonic environments. The presence of peptidoglycan is a defining characteristic of bacterial cells and is a key factor in differentiating between gram-positive and gram-negative bacteria based on the thickness of this layer.

While other options present different functions, they are not associated with peptidoglycan. For instance, energy sources for bacteria typically include carbohydrates or lipids rather than peptidoglycan. Additionally, DNA replication is facilitated by various enzymes and proteins, not by peptidoglycan, and photosynthesis pigments are primarily associated with chlorophyll and carotenoids found in photosynthetic organisms, rather than in the peptidoglycan structure. Thus, the role of peptidoglycan is specifically tied to maintaining the integrity and shape of the bacterial cell wall.