biology genes definition
Gene. Definition. noun, plural: genes. (cell and molecular biology). The fundamental, physical, and functional unit of heredity. Supplement. It is because a gene is a segment of DNA (on a specific site on a chromosome) that is responsible for the physical and inheritable characteristics or phenotype of an organism.It also specifies the structure of a protein, and an RNA molecule. A gene is formerly called a factor.t is because a gene is a segment of DNA (on a specific site on a chromosome) that is responsible for the physical and inheritable characteristics or phenotype of an organism. It also specifies the structure of a protein, and an RNA molecule. A gene is formerly called a factor.