Final answer:
Eubacteria have distinct structures such as a peptidoglycan cell wall, circular chromosomal DNA, and in some cases, a polysaccharide capsule, flagella, pili, and fimbriae, differentiating them from eukaryotic cells.
Step-by-step explanation:
Eubacteria, also known as true bacteria, have several unique cell structures or characteristics that set them apart from eukaryotic cells. Unlike eukaryotes, eubacteria do not have a nucleus or membrane-bound organelles such as mitochondria and chloroplasts. Instead, the bacterial chromosomal DNA is circular and housed in a region called the nucleoid. One of the most notable features of eubacteria is their cell wall made of peptidoglycan, which provides structural support and protection. They may also have a protective polysaccharide capsule. Additionally, for movement and adherence, some eubacteria possess flagella, while others have pili or fimbriae used for genetic material exchange and attachment to other cells or surfaces. These specialized structures make eubacteria distinct and are important targets for antibiotics, demonstrating their significance in both environmental and medical contexts.