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.
In exothermic reactions, some of the reactants' potential energy or enthalpy is released into the surroundings, usually in the form of heat. As a result, the enthalpy of the products is less than the enthalpy of the reactants.