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| Hybrid | Offspring resulting from mating between two genetically different kinds of parents--the opposite of purebred. |
| genetics | The study of gene structure and action and the patterns of inheritance of traits from parent to offspring. This is the branch of science that deals with the inheritance of biological characteristics. |
| purebred | Offspring that are the result of mating between genetically similar kinds of parents--the opposite of hybrid. |
| gene | Units of inheritance usually occurring at specific locations, or loci, on a chromosome. These units are responsible for hereditary characteristics in plants and animals. |
| allele | Alternate forms of the same gene. May result in different appearance of a trait. |
| genotype | The genetic makeup of an individual for a trait |
| homozygous | A genotype consisting of two identical alleles of a gene for a particular trait. |
| heterozygous | A genotype consisting of two different alleles of a gene for a particular trait. |
| phenotype | The observable characteristics of an organism. |
| dominant | The general term for an allele that masks the presence of another allele in the phenotype. Only 1 copy needed to see trait. |
| recessive | The general term for an allele that is masked in the phenotype by the presence of another allele. Two copies necessary to see trait. |
| Law of Segregatation | the pair of genes of each parent separate (during the formation of sex cells) and only one gene from each parent passes on to an offspring. |
| Law of Independent Assortment | different pairs of genes are passed to offspring independently so that new combinations of genes, present in neither parent, are possible. |
| Punnett square | method of showing all of the potential combinations of offspring genotypes that can occur and their probability given the parent genotypes. |
| homozygous dominant | The term for a genotype in which there are two dominant alleles. |
| heterozygous | The term for a genotype in which there is a dominant allele and a recessive one. |
| homozygous recessive | The term for a genotype in which there are two recessive alleles. |
| carrier | The genotype of an individual who is heterozygous for a recessive trait that is not expressed in his/her phenotype. |
| sex-linked inheritance | Pattern of inheritance that occurs when a gene is located on the X chromosome. |
| XX | female (human) |
| XY | male (human) |
| pedigree | A family tree that demonstrates the pattern of inheritance of a particular trait. |
| monohybrid cross | Mating in which inheritance of one trait is analyzed. |
| dihybrid cross | Genetic cross in which the inheritance of 2 traits is analyzed. |
| testcross | Performed to determine whether individual with dominant phenotype is homozygous or heterozygous genotype. |
| parental generation | Original (purebred) parents used in a genetic study |
| F1 generation | Offspring of the parental generation |
| F2 generation | Offspring produced by mating F1 generation (grandkids of original mating). |
