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| genetics | the science of heredity and of the mechanisms by which traits are passed from parent to offspring |
| heredity | the transmission of traits from parents to their offspring |
| trait | a genetically determined variant of a character |
| pollination | the transfer of pollen from the male reproductive structures (the anthers) to the tip of a female reproductive structure (the pistil) of a flower in angiosperms or to the ovule in gymnosperms |
| anther | in flowering plants, the tip of a stamen which contains the pollen sacs where grains form |
| stigma | the expanded apex of the pistil, supported by the style, the part of the pistil that receives the pollen |
| self-pollination | the transfer of pollen from an anther to the stigma of the same flower or the stigma of a flower on the same plant |
| cross-pollination | a reproductive process in which pollen from one plant is transferred to the stigma of another plant |
| dominant | describes the allele that is fully expressed when carried by only one of a pair of homologous chromosomes |
| true-breeding | describes organisms or genotypes that are homozygous for a specific trait thus always produce offspring that have the same phenotype for that trait |
| P generation | parental generation, the first two individuals that mate in a genetic cross |
| F 1 generation | the first generation of offspring obtained from an experimental cross of two organisms |
| F 2 generation | the second generation of offspring, obtained from an experimental cross of two organisms, the offspring of F1 generation |
| recessive | describes a trait or an allele that is expressed only when two recessive alleles for the same characteristic are inherited |
| law of segregation | Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete |
| law of independent assortment | the law that states that the genes separate independently of one another in meiosis |
| molecular genetics | the study of the structure of nucleic acids and the function and regulation of genes |
| allele | one of the alternative forms of a gene that governs a characteristic such as hair color |
| genotype | the genetic composition of an organism with reference to a single trait, a set of traits, or the entire complement of traits in an organism |
| phenotype | the observable expression of a genotype, appearance |
| homozygous | describes an individual that has identical alleles for a trait on both homologous chromosomes |
| heterozygous | describes an individual that has two different alleles for a trait |
| probability | the likelihood that a possible future event will occur in any given instance of the event; the mathematical ratio of the number of times an outcome of any event is likely to occur to the number of possible outcomes of the event |
| monohybrid cross | a cross between individuals that involves one pair of contrasting traits |
| Punnett square | a graphic used to predict the results of a genetic cross |
| genotypic ratio | the ratio of genotypes that appear in the offspring |
| phenotypic ratio | the ratio of phenotypes produced by a cross |
| test cross | the crossing of an individual of unknown genotype with a homozygous recessive individual to determine an unknown genotype |
| complete dominance | a relationship in which one allele is completely dominant over another |
| incomplete dominance | a condition in which a trait in an individual is intermediate between the phenotype of the individual's two parents because the dominant allele is not able to express itself fully |
| codominance | a condition in which both alleles for a gene are fully expressed |
| dihybrid cross | a cross between individuals that have different alleles for the same gene |
| multiple alleles | more than two alleles(versions of a gene) for a genetic trait |
| polygenic trait | describes a characteristic that is influenced by many genes |
| sex linked trait | a trait that is determined by a gene found on one of the sex chromosomes , such as the X chromosome or Y chromosome in humans |
| recessive inheritance | a pattern of inheritance in which the phenotypic effect of one allele is only expressed within a homozygous genotype. In a heterozygous condition with a dominant allele, it is not expressed in the phenotype |
| selective breeding | the process of breeding organisms that result in offspring with desired genetic traits |
