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 an exothermic reaction the reactants release energy to the environment when they react - like coal burning. In an endothermic reaction the reactants need to absorb energy fâ¦rom their environment when they react, so the reaction feels cold in your hand, or else you have to heat it continually to make it react.