| A | B |
|---|
| allele | an alternative form of a gene |
| codominance | condition in which both alleles for a gene are expressed when present |
| continuous variation | a genetic pheonomenon in which a trait is controlled by several genes and therefore exhibits a variety of phenotypes |
| cross-pollination | transfer of pollen from the male structures of one plant to the female structures of a different plant of the same species |
| dihybrid cross | a cross that involves two pairs of contrasting traits |
| dominant | trait that is expressed when its allele is homozygous or heterozygous |
| F1 generation | the offspring from a cross of two varieties |
| F2 generation | the offspring from crosses among individuals of the F1 generation |
| genetic disorder | harmful effect, such as sickle cell anemia, produced by mutated genes |
| genetics | study of heredity |
| genotype | genetic constitution of an organism as indicated by its set of alleles |
| hemoglobin | component of red blood cells that binds with and carries oxygen through the body |
| hemophilia | genetic disorder that impairs the blood's ability to clot and can cause excessive bleeding |
| heredity | transmission of genetic traits from parent to offspring |
| heterozygous | refers to a pair of genes, or an individual, with two different alleles for a trait |
| homozygous | refers to a pair of genes, or an individual, with two identical alleles for a trait |
| incomplete dominance | condition in which a trait is intermediate between two parents |
| law of independent assortment | law stating that pairs of genes separate independently of one another in meiosis |
| law of segregation | law stating that pairs of genes separate in meiosis and each gamete receives one gene of a pair |
| monohybrid cross | cross involving one pair of contrasting traits |
| multiple alleles | having more than two alleles (versions of the gene) for a genetic trait |
| mutation | change in the DNA of a gene or chromosome |
| pedigree | family history of traitsrecorded over a generation |
| P generation | (parental generation) plants that displayed one form of a particular trait |
| phenotype | observable characteristic of a a trait |
| phenylketonuria (PKU) | genetic disorder in which an individual lacks an enzyme that converts the amino acid phenylalanine into the amino acid tyrosine |
| probability | the likelihood that a specific event will occur |
| Punnett square | diagram used by biologists to predict the probable outcome of a cross |
| recessive | the trait that is not expressed in F1 generation after crossing |
| self-pollination | process by which a plant pollinates itself |
| sex-linked trait | a trait that is determined by a gene found on the x chromosome |
| sickle cell anemia | condition caused by amutant allele that produces a defective form of the protein hemoglobin |
| true-breeding | displaying only one form of a particular trait in offspring |
