Alleles              alternative forms of a gene

Autosome         non-sex chromosome

Cross               mating between two individuals

Diploid             organism with two sets of chromosomes

Disjunction        separation of the pairs of chromosomes during meiosis

F1                    first filial generation

F2                    second filial generation, produced by F1 x F1 cross

Gamete             mature reproductive cell

Gene                determinant of a characteristic

Genotype          genetic composition of an organism

Haploid             organism with one copy of each chromosome

Heterozygous     diploid with two different alleles at one locus

Homozygous     diploid with two of the same allele at a locus

Locus                location of a gene on a chromosome

Phenotype         the physical expression of the genotype

Reciprocal cross    mating with the traits tested in turn in the partners of opposite sex

Trait                characteristic

Zygote              cell produced by the fusion of male and female gametes