Genotype and phenotype
The genotype is the set of alleles an organism carries; the phenotype is what the organism actually turns out to be, from its height and colouring to its behaviour and its blood chemistry. Johannsen drew the distinction in 1909 to stop the two being treated as the same thing. The phenotype is produced by the genotype together with the environment and with chance during development, so identical genotypes can give visibly different phenotypes.
Why it matters
The gap between the two is where most arguments about genetic determinism actually live, and keeping them apart is a precondition for reading anything on heritability.
Also written: genotype, phenotype
Where it comes up
Read about Genotype and phenotype on Wikipedia
Sources
- Genotype–phenotype distinction Wikipedia
- The Genotype/Phenotype Distinction Stanford Encyclopedia of PhilosophyOn why the distinction was drawn and what it does and does not license you to infer.
- Phenotype NHGRI Talking Glossary of Genetic Terms
