All prokaryotes have plasma membranes, cytoplasm, ribosomes, and DNA that is not membrane-bound. Electron microscopes provide higher magnification, higher resolution, and more detail than light microscopes.

The unified cell theory states that one or more cells comprise all organisms, the cell is the basic unit of life, and new cells arise from existing cells Prokaryotes are single-celled organisms of the domains Bacteria and Archaea.

cell — the smallest unit of life. unified cell theory — a biological concept that states that one or more cells comprise all organisms; the cell is the basic unit of life; and new cells arise from existing cells. cell wall — rigid cell covering comprised of various molecules that protects the cell, provides structural support, and gives shape to the cell. cytoplasm — entire region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals.