1- Readiness Reading: Mendel's Principles (1 of 3)

F₁ generation

The initial generation from an experimental cross—meaning, the offspring of the original parents.

F₂ generation

The second generation from an experimental cross—the offspring of F₁s.

Recessive allele

An allele with a phenotype that does not appear in heterozygous individuals.

Dominant allele

An allele with a phenotype that appears in heterozygous individuals.

Homozygous

Having two copies of the same allele for a gene.

Heterozygous

Having two different alleles for a gene.

Principle of segregation

The observation that alleles of the same gene separate from each other prior to gamete formation. Caused by the separation of homologous chromosomes at the end (anaphase and telophase) of Meiosis I.

Principle of independent assortment

The observation that alleles of different genes go into gametes independently of each other, making every combination of alleles from different genes equally likely. Caused by different chromosomes lining up independently of each other in the middle (metaphase) of Meiosis I, and holds if the genes in question are found on different chromosomes.