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.
Thus, an epithelium with a single layer of flattened cells is called a simple squamous epithelium. If the shape of the cells is not identical in the various layers of a stratified epithelium, it is the outermost layer (ie at the free surface) that determines the classification.or example, the epidermis is called a stratified squamous epithelium even though the cells in the basal layers are cuboidal, because the outermost layer of cells is squamous. Images of different types of epithelia are shown below.