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.
Many reactions produce heat. In fact, when students think of chemical reactions, heat production is often expected. However, endothermic reactions, reactions which consume heat, can be just as exciting. One of the most striking examples of this is when the solids barium hydroxide and ammonium thiocyanate are mixed together in a beaker.