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.
Simple Squamous Epithelial Tissue (400X) In this view the lumen associated with the epithelium cannot be seen because the viewer is looking down on the top (superior aspect) of the tissue. Notice how the nucleus is clearly seen in the center of each cell. Description: A single layer of flat cells.