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a region of a chromosome that codes for a specific triat


a version of a gene


both alleles are the same for a particular gene (TT or tt)


They have two different alleles for the trait (Tt)


the genetic composition of a certain trait (BB)


the physical apperance of a particular trait (Brown eyes)


the allele that is phenotypically expressed (T)


the allele that is not expressed (t)

Complete Dominance

if two alleles are present the phenotype of only one is expressed (Tall plant height)

incomplete Dominance

if two alleles are present the phenotype expressed is an intermediate of the two (AA=red BB=blue AB=purple)


if two alleles are present both phenotypes are expressed (AA=red BB=blue AB=red and blue stripes)


visual representation of the way a gene moves through a family. can be dominant, recessive or sex linked recessive.


Where one trait is controlled by more than one gene, e.g. human height and skin color

multiple genes

one of two or more alternative forms of a gene at corresponding sites (loci) on homologous chromosomes
ex. blood type

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