UNIT 2- Chapter 7C: Genotypes and phenotypes

homozygous

having identical alleles for the same gene on homologous chromosomes

heterozygous

having different alleles for the same gene on homologous chromosomes

dominant allele

the variant of a gene that masks the effect of a recessive allele of the same gene on a homologous chromosome

recessive allele

the variant of a gene that is masked by a dominant allele on
a homologous chromosome

complete dominance

a pattern of dominance where only the dominant allele from the genotype of a heterozygous individual is expressed in the phenotype of that organism

phenotype

the physical or biochemical characteristics of an organism that are the result of gene expression (or set of genes) and the environment

carrier

an organism that has inherited a copy of a recessive allele for a genetic trait but does not display the trait due to it being masked by the presence of a dominant allele

genotype

the genetic composition of an organism at one particular gene locus, as represented using letter symbols

codominance

a pattern of dominance where both alleles from the genotype of a heterozygous individual are dominant and expressed in the phenotype of that organism

incomplete dominance

a pattern of dominance where neither allele from the genotype of a heterozygous individual is dominant and both are expressed in an intermediate phenotype

sex-linked genes

genes that are located on a sex chromosome

x-linked traits

a trait controlled by a gene that is located on the X chromosome

y-linked traits

a trait controlled by a gene that is located on the Y chromosome