Genetic architecture refers to the underlying genetic basis of a phenotypic trait. It encompasses both the number of genes and their importance in determining the phenotype (e.g., many genes of small effect vs. few genes of large effect). The phenotype of an individual organism is either its total physical appearance and constitution, or a specific manifestation of a trait, such as size or eye color, that varies between individuals. ... In biology, a trait or character is a genetically inherited feature of an organism. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...