| A | B |
|---|
| allele | alternative form of a gene; occur at the same locus on homologous chromosomes |
| autosome | any chromosome other than the sex-determining pair |
| carrier | heterozygous individual who has no apparent abnormality but can pass on an allele for a recessively inherited genetic disorder |
| chromosome | structure consisting of DNA complexed with proteins that transmits genetic information from the previous generation of cells and organisms to the next generation |
| dominant allele | allele that exerts its phenotypic effect in the heterozygote; it masks the expression of the recessive allele |
| epistasis | inheritance pattern in which one gene masks the expression of another gene that is at a different locus and is independently inherited |
| gene locus | specific location of a particular gene on homologous chromosomes |
| genotype | genes of an organism for a particular trait or traits; designated by letters |
| heterozygous | possessing unlike alleles for a particular trait |
| homozygous | possessing two identical alleles for a particular trait |
| incomplete dominance | inheritance pattern in which the offspring has an intermediate phenotype |
| multiple alleles | inheritance pattern in which there are more than two alleles for a particular trait |
| phenotype | visible expression of a genotype |
| pleiotropy | inheritance pattern in which one gene affects many phenotypic characteristics of an individual |
| polygenic inheritance | inheritance pattern in which a trait is controlled by several allelic pairs; each dominant allele contributes to the phenotype in an additive and like manner |
| Punnett square | grid used to calculate the expected results of simple genetic crosses |
| recessive allele | allele that exerts its phenotypic effect only in the homozygote; its expression is masked by the dominant allele |
| testcross | cross between an individual with the dominant phenotype (unknown genotype) and an individual with the recessive phenotype (known genotype) |
| law of segregation | two chromosomes separate during formation of gametes so each gamete contains only one chromosome from each pair of chromosomes |
| law of independent assortment | each pair of chromosomes separates independently of the other chromosomes so all possible combinations of chromosomes can occur in the gametes |
| codominance | inheritance pattern in which both alleles are equally expressed |
