Term | Definition |
trait | one of two or more possible forms of a character; a recognizable feature or characteristic of an organism |
genetics | the science of heredity and of the mechanisms by which traits are passed from parents to offspring |
purebred | type of organism whose ancestors are genetically uniform |
cross | mating of two organisms |
law of segregation | Mendel's first law, stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene in their gametes because the genes separate during gamete formation |
gene | the most basic physical unit of heredity; a segment of nucleic acids that codes for a functional unit of RNA and/or a protein |
allele | one of the alternative forms of a gene that governs a characteristic, such as hair color |
homozygous | describes an individual that has identical alleles for a trait on both homologous chromosomes |
heterozygous | describes an individual that carries two different alleles of a gene |
genome | the complete genetic material contained in an individual or species |
genotype | the entire genetic makeup of an organism; also the combination of genes for one or more specific traits |
phenotype | an organism's appearance or other detectable characteristic that results from the organism's genotype and the environment |
dominant | in genetics, describes an allele that is fully expressed whenever the allele is present in an individual |
recessive | in genetics, describes an allele that is expressed only when no dominant allele is present in an individual |
Punnett Square | a graphic used to predict the results of a genetic cross |
monohybrid cross | a cross between individuals that involves one pair of contrasting traits |
testcross | cross between an organism with an unknown genotype and an organism with a recessive phenotype |
dihybrid cross | a cross between individuals that have different alleles for the same gene |
law of independent assortment | the law that states the genes separate independently of one another in meiosis |
probability | the likelihood that a possible future event will occur |
crossing over | exchange of chromosome segments between homologous chromosomes during meiosis I |
genetic linkage | tendency for genes located close together on the same chromosome to be inherited together |