The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated.
It is the interaction of two or more substances, resulting in chemical changes in them. Chemical reactions take place when some kind of energy is supplied to them. The supplied energy may be in the form of heat, light or mechanical shaking for proper contact between the reactant molecules or electricity.
There are two theories as to how reactions occur: 1  In the collision theory, it is thought that reactions occur because molecules collide; the faster they collide, the faster the reaction occurs. 2  In the transition state theory, reactants are thought to form bonds and then break bonds until they form products.