Types of Compounds. Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons. 1  A cation is a positively charged ion. 2  An anion is a negatively charged ion.
Porins are members of an extended family of transmembrane proteins found in the outer membrane of gram negative bacteria such as E. coli, or in the outer membranes of mitochondria in eukaryotes. The general porins provide a simple diffusion pathway across the membrane for molecules less than 1 kDa with little substrate selectivity.
Protein Structure and Function. A protein is a functional biological molecule that is made up of one or more polypeptides that are folded/coiled into a specific structure . Proteins are important macromolecules that serve as structural elements, transportation channels, signal receptors and transmitters, and enzymes.