| A | B |
|---|
| Allele | One of a pair of genes that occupies the same position on homologous chromosomes |
| Autosomal inheritance | Inheritance of a genetic trait not on a sex chromosome |
| Autosomes | Chromosomes that do not determine the sex of an individual |
| Change in chromosome number | A situation in which abnormal cellular events in meiosis lead to either none of a particular chromosome in the gamete or more than one chromosome in the gamete |
| Change in chromosome structure | A situation in which the chromosome loses or gains genes during meiosis |
| Dihybrid cross | A cross between two individuals concentrating on two definable traits |
| Dominant allele | An allele that will determine phenotype if even one is present in the genotype |
| Genetic disease carrier | A person who is heterozygous in a recessive genetic disorder |
| Genotype | Two-letter set that represents the alleles an organism possesses for a certain trait |
| Heterozygous genotype | A genotype with two different alleles |
| Homozygous genotype | A genotype in which both alleles are identical |
| Monohybrid cross | A cross between two individuals concentrating on only one definable trait |
| Mutation | A radical chemical change in one or more alleles |
| Pedigree | A diagram that follows a particular species' phenotype through several generations |
| Phenotype | The observable expression of an organism's genes |
| Recessive allele | An allele that will not determine the phenotype unless the genotype is hornozygous with that allele |
| Sex chromosomes | Chromosomes that determine the sex of an individual |
| Sex-linked inheritance | Inheritance of a genetic trait located on the sex chromosomes |
| True breeding | If an organism has a certain characteristic that is always passed on to all of its offspring, we say that this organism bred true with respect to that characteristic. |
