Atoms make up large molecules that are the substances of life. At the macromolecular level of life, a difference starts to emerge between living and nonliving material. DNA holds the secrets of life. Encoded in the DNA sequence is information for numerous proteins that have both structural and regulatory functions. Among the proteins found in cells are enzymes that catalyze biochemical reaction.
Enzymes speed up the rate of a reaction that allows life to continue.
A simple way to think of the flow of information from DNA to mRNA to protein is the molecular trinity that is central to all life and is known as the central dogma. We may think of humans as individuals who enter the world abruptly and leave the same way. This is not the way it happens however, our genes existed before birth and will exist after our death if we succeed in reproduction. Cells can arise only from cells that already exist. They do this by one of life's defining features, reproduction.