From Biology-Online Dictionary | Biology-Online Dictionary


noun, plural: genes

(cell and molecular biology) The fundamental, physical, and functional unit of heredity


A gene is the fundamental, physical, and functional unit of heredity. It is because a gene is comprised of nucleotides (on a specific site on a chromosome) that is responsible for the physical and heritable characteristics or phenotype of an organism. It therefore specifies the structure of a protein, and an RNA molecule. The genes make up the sequences of DNA (genotypes). The genotypes, together with the other factors (e.g. environmental factors), determine the phenotypic trait of an organism. These changes in the genes drive evolution and natural selection.

The genes may acquire genetic changes (i.e. mutations). When genes mutate, variants (called alleles) are formed and this results in differences in phenotypic traits within a population.

A gene is formerly called a factor. It was then called gene as introduced by Wilhelm Johannsen, a Danish botanist and plant physiologist, in 1905.

Word origin: German gen, from gen ("begetting"), from Greek genos ("race, offspring")


  • factor (obsolete)

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