Final answer:
DNA plays a fundamental role in heredity and the regulation of cellular processes, according to the central dogma of molecular biology, which states that DNA codes for RNA, which makes proteins. These proteins then determine an organism's phenotype, the physical expression of its genotype.
Step-by-step explanation:
The central role that DNA plays in driving the existence of living organisms is best characterized as its function in heredity and regulation of cellular processes. DNA contains all of the genetic information necessary to build and maintain an organism, functioning as the blueprint for all cellular structures and functions. The central dogma of molecular biology encapsulates this concept by illustrating that DNA codes for RNA, which in turn codes for proteins, the molecules that execute various functions within the cell.
The genetic instructions contained within a cell’s DNA are referred to as its genotype. The phenotype is the observable manifestation of these instructions, which is expressed through the characteristics and behaviors of the organism, influenced by the proteins produced at any given time. Proteins play a critical role in determining the phenotype, as they are the end products of gene expression and are responsible for the myriad of functions necessary for an organism's survival.
The genetic flow from DNA to RNA to proteins represents the core process by which genetic information is expressed. A genome, which includes all the genetic material in an organism, is divided into genes. These genes are segments of DNA that contain the instructions for making proteins. The information within the genes is transcribed into messenger RNA (mRNA), and the mRNA is then translated into the specific sequence of amino acids that form proteins. Proteins, being the workhorses of the cell, contribute to the structure and function of cellular components and essentially determine the organism’s characteristics.