Definitions

Trait - A characteristic determined by genetics.

P Generation - The original parent generation in a cross.

F1 Generation - First-generation offspring of the P generation.

F2 Generation - Offspring from crossing F1 individuals.

True-Breeding - Organisms that produce offspring identical to themselves when self-pollinated.

Allele - Variant form of a gene.

Dominant - Allele that masks the effect of a recessive allele.

Recessive - Allele only expressed in a homozygous state.

Phenotype - Observable traits.

Genotype - Genetic makeup.

Punnett Square - A diagram to predict offspring genotypes.

Homozygous - Having two identical alleles.

Heterozygous - Having two different alleles.

Hemizygous - Having only one allele of a gene, typical for males in X-linked traits.

Testcross - Cross with a homozygous recessive to determine an unknown genotype.

Monohybrid - Cross involving one trait.

Dihybrid - Cross involving two traits.

Law of Equal Segregation - Alleles separate equally into gametes.

Law of Independent Assortment - Genes on different chromosomes separate independently.

X-Linked - Gene located on the X chromosome.

Autosomal - Gene located on a non-sex chromosome.

Codominance - Both alleles in a heterozygote are fully expressed.

Trisomy - Condition with an extra chromosome.

Non-disjunction - Failure of chromosomes to separate properly during meiosis.

Pleiotropic - One gene influences multiple phenotypic traits.

Polygenic - Trait controlled by multiple genes.

Epistasis - Interaction where one gene affects the expression of another.

X Inactivation - Process by which one of the X chromosomes is silenced in females.