homologous chromosomes
pairs of chromosomes that have the same size, shape, and carry genes for similar information. they pair up during meiosis, then segregate into separate sex cells.
locus
a point on a chromosome where a gene is located.
alleles
different forms of the same gene. they may occupy the same locus on a pair of homologous chromosomes.
genotype
pairs of genes that an individual has for a certain characteristic. ex: GG, Gg, gg
heterozygous
when the genotype has both genes different for a particular characteristic. hybrid is a synonym. ex: Gg
homozygous
when the genotype has both genes the same for a particular characteristic. true or pure-breeding is a synonym. ex: GG or gg
phenotype
the physical appearance of an individual. ex: brown eyes, blond hair, long wings
dominant gene
a gene that masks the effect of another gene in the heterozygous condition.
recessive gene
a gene whose effect is masked by a dominant gene in the heterozygous condition.