Law of independent assortment
The law that states the genes separate independently of one another in meiosis.
Law of segregation
States that a pair of factors is segregated, or separated, during the formation of gametes.
Meiosis
Cell division that produces sex cells.
Allele
One form of a gene - ex: the dominant allele (B) or recessive allele (b).
Co-dominance
Condition in which two or more alleles are equally dominant and when both are present, both alleles are fully expressed - ex: in human blood type, the A allele and the B allele are co-dominant.
Dominant
The allele that when present masks the expression of another allele - ex: the allele for green pods (G) is dominant over the allele for yellow pods (g).
Gene
Segment or sequence of DNA that codes for a protein.
Genotype
The combination of alleles for a gene - ex: BB, Bb, or bb.
Heredity
Gene transmission from parent to offspring.
Heterozygous
Two different alleles - ex: Genotype Bb.
Homozygous
Two identical alleles - ex: Genotype BB or bb.
Incomplete Dominance
Condition in which neither allele is dominant over the other and the heterozygote shows a blend of the two phenotypes - ex: in snapdragons the R (red) allele is incompletely dominant to the W (white) allele Heterozygous (RW) are pink.
Phenotype
The expression of a gene - ex: blue eyes, white flowers, curly hair, widow's peak.
Recessive
The allele that is masked by the dominant allele; in order to be expressed, two copies of this allele must be present - ex: the allele for yellow pods (g) is recessive to the allele for green pods (G).
Sex linked genes
Genes that are present only on the x chromosome of the sex chromosomes - ex: hemophilia is a trait controlled by a recessive allele located on the x chromosome.
Trait
A characteristic or feature - ex: eye color, height.