Membrane potentialMembrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. That is, there is a difference in the energy required for electric charges to move from the internal to exterior cellular environments and vice versa, as long as there is no acquisition of kinetic energy or the production of radiation. The concentration gradients of the charges directly determine this energy requirement.
Cell wallA cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes (except mollicute bacteria). A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.
Basement membraneThe basement membrane, also known as base membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between epithelial tissues including mesothelium and endothelium, and the underlying connective tissue. As seen with the electron microscope, the basement membrane is composed of two layers, the basal lamina and the reticular lamina.
ConnexonIn biology, a connexon, also known as a connexin hemichannel, is an assembly of six proteins called connexins that form the pore for a gap junction between the cytoplasm of two adjacent cells. This channel allows for bidirectional flow of ions and signaling molecules. The connexon is the hemichannel supplied by a cell on one side of the junction; two connexons from opposing cells normally come together to form the complete intercellular gap junction channel.
