1dominant
Describes an allele or trait that is expressed in heterozygotes. Only one dominant allele is needed to express the phenotype.
2recessive
Describes an allele or trait that is only expressed in homozygotes, and not expressed in heterozygotes. Two recessive alleles are needed to express the phenotype.
3alleles
Different forms of a gene, corresponding to different DNA sequences.
4monohybrid cross
A cross between two individuals that are hybrids for a single gene, meaning they possess two different alleles.
5law of segregation
The principle that half of the gametes receive one allele of a gene and half receive the other allele. This principle is explained by meiosis, in which the maternal and paternal homologous chromosomes separate during anaphase I.
6homozygous
A condition in which an individual possesses two identical alleles for a given gene.
7heterozygous
A condition in which an individual possesses two identical alleles for a given gene.
8probability
The likelihood of an event happening.
9addition rule of probability
Rule which states that the probability of two mutually exclusive events happening is the sum of their individual probabilities.
10multiplication rule of probability
A rule which states that the probability of two independent events both happening is the product of their individual probabilities.
11Chi-square (X^2) test
A statistical test that determines whether the number of observed events in different categories differs from an expected number of events.
12law of independent assortment
The principle that segregation of one set of alleles for one gene is independent of the segregation of a second set of alleles for a different gene.
13dihybrid cross
A mating in which hybrid individuals differ in two traits that are coded by two different genes.
14pedigree
A visual mapping of phenotypes using ancestral relationships.