Vocabulary #1 ¬¬

allele	two or more molecular that arise by mutation and code for different versions of the same trait.
codominance	In heterozygotes, simultaneous expression of a pair of nonidentical alleles that specify different phenotypes.
continuous variation	Of a population, a more or less continuous range of small differences in a given trait among its individuals.
dihybrid cross	An intercross between two F1 heterozygotes that are identical for two gene loci; the dihybrids are offspring of parents that bred true for different versions of two traits.
epistasis	Interaction among the products of two or more gene pairs.
F1	The offspring of an initial genetic cross.
F2	The offspring of parents who are the first filial generation from a genetic cross.
gene	Unit of information for a heritable trait, passed from parents to offspring.
genotype	Genetic constitution of an individual; a single gene pair or the sum total of an individual's genes.
heterozygous	Having a pair of nonidentical alleles at a gene locus (that is, on a pair of homologous.
homozygous dominant	Having a pair of dominant alleles at a gene locus.
homozygous recessive	Having a pair of recessive alleles at a gene locus .
hybrid offspring	Of a genetic cross, offspring having a pair of nonidentical alleles for a trait.
incomplete dominance	Condition in which one allele of a pair is not fully dominant; a heterozygous phenotype somewhere between both homozygous phenotypes emerges.
independent assortment	Mendelian theory that by the end of meiosis, each pair of homologous chromosomes are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
monohybrid cross	Intercross between two F1 heterozygotes that are identical for one gene locus; offspring of two parents that breed true for different forms of a trait.
multiple allele system	Three or more slightly different molecular forms of a gene that occur among individuals of a population.
phenotype	Observable trait or an individual that arise from gene interactions and gene-environment interactions.
pleiotropy	Positive or negative effects on two or more traits of alleles at a single gene locus. Effects may or may not emerge
probability	The chance that each outcome of a given event will occur is proportional to the number of ways the outcome can be reached.
Punnett-square method	Construction of a simple diagram ,to predict probable outcomes of a genetic cross.
segregation	Sexually reproducing organisms inherit pairs of genes each pair are separated from each other at meiosis, and they end up in separate gametes.
testcross	Experimental cross to determine an individual of unknown genotype that shows dominance for  homozygous dominant or heterozygous.
true-breeding lineage	Of sexually reproducing species, a lineage in which only one version of a trait appears over the generations in all parents and their offspring