Genes are the sources of information used for creating amino acids which are then assembled to form protein structures (molecules). Together, the various protein structures function in different catalytic and structural activities that are responsible for establishing the phenotypes we see. Although both gene and proteins are equally involved in the biological functions that determine phenotypes, considerable amount of time has been portioned, by geneticists and breeders alike, for dissection of gene architecture and its characteristics comparative to proteins. Proteins are the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes. They function as catalysts, they transport and store other molecules such as oxygen, they provide mechanical support and immune protection, they generate movement, they transmit nerve impulses, and they control growth and differentiation. Indeed, much of this text will focus on understanding what proteins do and how they perform these functions. Understanding protein structure and its functions is instrumental for advancing molecular sciences. This review attempts to shed some light on structure of proteins, relationship between amino acid sequence and DNA base sequence, hierarchical nature of protein structure as well as the relationship between protein structure and its functions. The information synthesized could provide an insight into the complex nature of proteins and its importance in the perception of biological sciences.