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.
Chemical reactions most often result from the introduction of heat, radiation or other chemicals. These disturb the equilibrium and cause breakage and formation of the existing chemical bonds. Spontaneous Combustion, Chemical Reactions and Fire. The results of chemical reactions that occur during spontaneous combustion are light and heat.