Vocabulary #1 : Patterns of Inheritance

Allele

 one molecular form of a gene that arise by mutuation and code for different versions of the same trait.

Codominance

 simultaneous expression of nonidentical alleles pairs that specify different phenotypes.

Continuous variation

 population of more or less continuous range of small differences in a given trait among its individuals.

Dihybrid cross

 intercross between two F1 heterozygotes that are identical for two gene loci.

 

Epistasis

 product interaction of two or more gene pairs .

F1

 offspring of initial genetic cross.

F2

 Parents offspring who are the first filial generation from a genetic cross.

Gene 

 information for a heritable trait, from parents to offspring.

 

Genotype

 genetic constitution; single gene pair or the sum total of an individual's genes.

Heterozygous

 pair of nonidentical alleles at a gene locus.

Independent assortment

Mendelian Theory, each pair of homologous chromosomes are sorted before shipment to gametes independly of how the other pairs were sorted. 

Pleiotropy

Positive or negative effects on two or more traits owing to expression of alleles at a single gene locus. Maybe effects emerge at the same time.

 
Probability

Chance that each outcome of a given event will occur is proportional to the number of ways the outcome can be reached.

Punnet Square Method 

Simple diagram construction as a way to predict probable outcomes of genetic cross.

Segregation

States that allele pairs separate during gamete formation, and randomly unite at fertilization.

Testcross

A cross between an individual with an unknown genotype and an individual with the homozygous recessive genotype.

True-breeding lineage

Occurs when offspring inherited identical alleles, generation after generation.

Monohybrid Cross

Intercross between two F1 heterozygotes that are identical for one gene locus.

Multiple Allele System  

Three or more different molecular forms of a gene that occur among individuals of a population.

Homozygous dominant

  

pair of dominant alleles at a gene locus.

Homozygous Recessive

pair of recessive alleles at a gene locus

Hybrid offspring

In 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.

Phenotype

Occurs when offspring inherited identical alleles, generation after generation.