classification system used to categorize organisms based on their genetic characteristics; organism's full hereditary information, part (DNA sequence) of the genetic makeup of a cell, one of three factors that determine phenotype

The genotype is the genetic constitution of an organism, mainly its genome.[1] The term is contrasted with the term phenotype, as follows:

genotype + environment → phenotype

The terms were invented by Wilhelm Johanssen to distinguish between inherited and environmentally produced variation.[2] "The distinction was not new. It had, for instance, been discussed by Francis Galton as nature vs. nurture.[3]

The extent to which the genotype influences the phenotype varies hugely. Some aspects of the phenotype are almost entirely determined by heredity, such as eye colour and blood types. Human language is an interesting case. The capacity to learn and speak a language is entirely inherited, but which language is spoken is entirely learnt, and hence is environmental.

References change

  1. King R.C. Stansfield W.D. & Mulligan P.K. 2006. A dictionary of genetics, 7th ed. Oxford. p179
  2. Johannsen W. 1911. The genotype conception of heredity. American Naturalist 45, 129-159
  3. Sturtevant A.H. 1965. History of genetics. Harper & Row, N.Y. p59