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.
For these reactions to take place, the following elements are necessary: 1  Precursor compounds: these compounds are the starting molecules or substrates in a reaction. 2  These may also be viewed as the reactants in a given chemical process. 3  Chemical energy: chemical energy can be found in the form of high energy molecules.