Complementation: a concept where an additional alleleplugin-autotooltip__default plugin-autotooltip_bigAllele: a version of a gene. Alleles of a gene are different if they have differences in their DNA sequence. of a geneplugin-autotooltip__default plugin-autotooltip_bigGene: read Chapters 02, 03, 04, 05, and 06 for a definition of gene :-) (usually a wildtypeplugin-autotooltip__default plugin-autotooltip_bigWildtype: a reference strain of an organism that scientists operationally define as “normal” to which mutants are compared. Not to be confused with wild organisms. alleleplugin-autotooltip__default plugin-autotooltip_bigAllele: a version of a gene. Alleles of a gene are different if they have differences in their DNA sequence.) can provide normal function to an organism with a recessiveplugin-autotooltip__default plugin-autotooltip_bigRecessive: used to describe an allele, usually in comparison to wildtype. Recessive alleles do not exhibit their phenotype when combined with a wildtype allele. loss of functionplugin-autotooltip__default plugin-autotooltip_bigLoss of function: a general term used to describe mutant alleles that have less activity than wildtype. Amorphic and hypomorphic mutations are loss of function mutations. mutationplugin-autotooltip__default plugin-autotooltip_bigMutation: a change in the DNA of a gene that results in a change of phenotype compared to a reference wildtype allele. See also: mutant. in that geneplugin-autotooltip__default plugin-autotooltip_bigGene: read Chapters 02, 03, 04, 05, and 06 for a definition of gene :-). The concept of complementation underlies the complementation testplugin-autotooltip__default plugin-autotooltip_bigComplementation test: a genetic experiment that answers the question: how many different genes are represented within a collection of mutants?.