Failure of one of a pair of genes (alleles) present in an individual to express itself in an observable manner because of the greater influence, or dominance, of its opposite-acting partner. Both alleles affect the same inherited characteristic, but the presence of the recessive gene cannot be determined by observation of the organism; that is, though present in the organism's genotype (gene makeup), the recessive trait is not evident in its phenotype (observable characteristics). The term recessive is applied both to the trait in the organism having the alleles of a gene pair in the recessive condition and to the allele whose effect can be masked by another allele of the same gene.
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In genetics, the greater influence by one of a pair of genes (alleles) that affect the same inherited trait. If an individual pea plant that has one allele for tallness and one for shortness is the same height as an individual that has two alleles for tallness, the tallness allele is said to be completely dominant. If such an individual is shorter than an individual that has two tallness alleles but still taller than one that has two shortness alleles, the tallness allele is said to be partially or incompletely dominant and the shortness allele is said to be recessive (see recessiveness).
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