At the chemical level, the DNA of prokaryotic cells, which have no nuclear membranes, and that of eukaryotic cells, which have separate, membrane-enclosed nuclei, is identical. DNA is a long, double-stranded molecule containing a backbone of repeating, alternating sugar and phosphate units.
Simple cuboidal epithelium is a type of epithelial tissue found in the body. It is a single layer thick and made of cube-shaped cells. This type of tissue is found lining parts of the body such as the kidney tubules and walls of respiratory bronchioles.
Flattened epithelium that consists of only a single layer of cells is called simple squamous epithelium. Epithelium composed of more than one layer of cells is called stratified epithelium. Simple squamous epithelium lines internal body surfaces that are not usually exposed to irritation, explains Rutgers University.