A variety of different proteins are embedded in the bilayer or positioned at its two surfaces. The Bacteria A. Bacteria are some of the smallest and simplest cells. A somewhat rigid cell wall supports the cell and surrounds the plasma membrane, which regulates transport into and out of the cell. Ribosomes, protein assembly sites, are dispersed throughout the cytoplasm. An Overview 1.
All eukaryotic cells contain organelles .
Organelles form compartmentalized portions of the cytoplasm. Organelles separate reactions with respect to time and space. The nucleus controls access to DNA and permits easier packing of DNA during cell division. Golgi bodies modify, sort, and ship proteins. The cytoskeleton determines cell shape and provides for motility.