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.
Heat stress occurs when the body heats up beyond its tolerance limit because its built-in cooling mechanisms are unable to prevent overheating. This often happens as a result of extreme physical activity or spending t much time outdoors under intensely hot sunshine, or staying too long in hot areas, such as a sauna.