The cellular component responsible for transmission of traits and control of cell function was long assumed to be proteins. discuss the characteristics of proteins and dna that made protein initially seem the more likely candidate, and outline the seminal studies that implicated dna as the molecule of heredity and determination of trait.

Proteins are considered as building blocks of the body, from structure, enzymes, transport of small molecules, hormones, and other bodily functions. People may have thought that these proteins are responsible for passing traits from generation to generation because there is evidence of function. For instance, a person with sickle cell anemia (problem with the protein hemoglobin) passes the trait to his child. Scientists back then hypothesized that proteins are responsible for heredity. But further research holds that untrue. First, proteins are complex and bulky molecules that has specific functions and a misplaced or deleted amino acid (amino acids are the basic units of proteins) may affect the function drastically. Having them be passed from one generation to another may produce an error in the amino acid sequence and therefore the function. Second, the entire number of proteins in the body are almost innumerable to be contained in one cell and determine functions. So the idea is that, there must be a molecule, with a structure simple enough to code for proteins, compact enough to fit in the cells' nuclei, and reselient to damage, hence DNA.