DNA is considered the molecule of life because it contains the instructions that ensure the continuity of life. Employment of DNA to code for protein is the basis of all life on earth.
In all living things, inherited DNA is used to code for amino acids which when joined or linked together in a deliberate specific manner form polypeptides which make up proteins. These proteins are responsible for structure and function of cells.
For example DNA provides information to make four polypeptide (two beta and two alpha ) chains which make up hemoglobin, the protein that functions as the oxygen carrier in red blood cells. In summary,
DNA → protein → trait, and that relationship is the physical basis of life.
