Final answer:
Eukaryotes have complex cells with a nucleus, while archaea and bacteria are prokaryotes without a nucleus. Bacteria have cell walls with peptidoglycan, unlike archaea, which have unique cell walls and live in extreme environments.
Step-by-step explanation:
Distinguishing the specific molecules found in eukaryotes, archaea, and bacteria is essential for understanding the fundamental differences between these domains of life. Eukaryotes are characterized by cells with a nucleus and other membrane-bound organelles. In contrast, both archaea and bacteria are classified as prokaryotes, which lack these structures. However, archaea and bacteria differ significantly in their cell wall composition, genetics, and metabolic pathways. The cell walls of bacteria are made of peptidoglycan, whereas archaea have unique cell wall compositions that do not contain peptidoglycan and often have ether linkages in their membrane lipids. Moreover, archaea are known to thrive in extreme environments, such as hot springs and salt flats, environments in which bacteria are not typically found.