molecular biology. (mÉ-lÄk'yÉ-lÉr) The branch of biology that deals with the formation, structure, and function of macromolecules essential to life, such as nucleic acids and proteins, including their roles in cell replication and the transmission of genetic information.
Molecules containing more than two atoms are termed polyatomic molecules, e.g., carbon dioxide (CO2) and water (H2O). Polymer molecules may contain many thousands of component atoms. A water molecule is made up of two hydrogen atoms and one oxygen atom. A single oxygen atom contains six electrons in its outer shell, which can hold a total of eight electrons. When two hydrogen atoms are bound to an oxygen atom, the outer electron shell of oxygen is filled. EncyclopÃ¦dia Britannica, Inc.
A molecule is two or more ATOMS (composed of protons (+) and neutrons (0) to make the nucleus, and orbited by electrons (-) bonded together. They may be the same type of atom (which means that the molecule is an ELEMENT), or they may be different types of atoms (which means that the molecule is a COMPOUND).