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.
Confidence votes 18.3K. In a battery, chemical reactions occur as two half reactions, each half reaction occurring at one of the two principal electrodes of the battery. One of the half reactions is an oxidation and the other is a reduction.hemical reactions occur so that atoms gain stability. For example, oxygen will react with carbon because the product, carbon dioxide, has more chemical stability-in other w â¦ ords, each atom shares its electrons to give the other atom(s) in the molecule an electron arrangement of more stability that the one before.