| A | B |
|---|
| allele | one of two or more different versions of the same gene |
| dominant allele | allele that masks the presence of another allele for the same gene when they occur together in a heterozygote |
| genetics | the science of heredity |
| genotype | alleles an individual inherits at a particular genetic locus |
| heterozygote | organism that inherits two different alleles for a given gene |
| homozygote | organism that inherits two alleles of the same type for a given gene |
| hybrid | offspring that results from a cross between two different types of parents |
| law of independent assortment | Mendel’s second law stating that factors controlling different characteristics are inherited independently of each other |
| law of segregation | Mendel’s first law stating that the two factors controlling a characteristics separate and go to different gametes |
| locus | position of a gene on a chromosome |
| pollen | tiny grains that bear the male gametes of seed plants and transfer sperm to female reproductive structures |
| pollination | fertilization in plants in which pollen is transferred to female gametes in an ovary |
| recessive allele | allele that is masked by the presence of another allele for the same gene when they occur together in a heterozygote |
| codominace | relationship between two alleles for the same gene in which both alleles are expressed equally in the phenotype of the heterozygote |
| incomplete dominance | relationship between the alleles for a gene in which one allele is only partly dominant to the other allele so an intermediate phenotype results |
| polygenic characteristic | characteristic, or trait, controlled by more than one gene, each of which may have two or more alleles |
| probability | the likelihood, or chance, than a certain event will occur |
| Punnett square | chart for determining the expected percentages of different genotypes in the offspring of two parents |
| phenotype | characteristics of an organism that depend on how the organism’s genotype is expressed |
