Term | Definition |
Trait | A particular version of a characteristic that is inherited, such as hair colour or blood type. |
True-breeding organism | An organism that produces offspring that are genetically identical for one or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits. |
Hybrid | The offspring of two different true –breeding plants. |
Cross | The successful mating of two organisms from distinct genetic lines. |
P generation | The parent plants used in a cross. |
F1 generation | The offspring of a P-generation cross. |
Monohybrid cross | The offspring of two different true-breeding plants that differ in only one characteristic. |
F2 generation | The offspring of a F1-generation cross. |
Law of segregation | Scientific law stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene to their gametes because the genes separate during gamete formation. |
Allele | A specific form of gene. |
Homozygous | An individual that carries two of the same alleles for a given characteristic. |
Heterozygous | An individual that carries two different alleles for a given characteristic. |
Genotype | The genetic makeup of an individual. |
Phenotype | An individual’s outward appearance with respect to a specific characteristic. |
Dominant allele | The allele that, if present, is always expressed. |
Recessive allele | That allele that is expressed only if it is not in the presence of the dominant allele, that is, if the individual is homozygous for the recessive allele. |
Punnett square | A diagram that summarizes every possible combination of each allele from each parent; a tool for determining the probability of a single offspring having a particular genotype. |
Probability | The likelihood that an outcome will occur if it is a matter of chance. |
Test cross | A cross used to determine the genotype of an individual expressing a dominant trait. |