All biomolecules have a turn over which means that they are constantly being changed into some other biomolecules and also made from some other biomolecules. Every chemical reaction occurring in the body is a catalysed reaction. There is no uncatalysed metabolic conversion in living systems. Metabolites are converted into each other in a series of linked reactions called metabolic pathways. These metabolic pathways are similar to the automobile traffic in a city. These pathways are either linear or circular. These pathways crisscross each other, i.e., there are traffic junctions. Living state is a non-equilibrium steady-state to be able to perform work.