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