mendelian inheritance

discrete characteristics

varied in “either or” pattern

true breeding

organism always passes down a specific phenotypic trait

discontinuous variation

variation seen among individuals when each individual shows one of 2 easily distinguishable traits

testcross

dominant pheno x homo recessive

principles of paired factors

each trait is controlled by a pair of 2 factors, 1 inherited from each parent

factor=allele

principle of dominance

one factor or allele in a pair marks/inhibits the expression of the other

law of segregation

alleles of a gene separate into different gametes in equal number; each gamete only has 1 allele

law of independent assortment

alleles for diff traits assort independently of one another during gamete formation

confounding features of inheritance

factors/phenomena that complicate the straightforward application of Mendel’s laws of inheritance

complete dominance

occurs when phenotypes of heterozygote and dominant homo are identical

incomplete dominance

phenotypes of F1 hybrids are somewhat in between two parental varieties

codominance

2 dominant alleles affect phenotype in separate but distinguishable ways

multiple alleles

genes with more than 2 alleles

ex) hair color and blood group

pleiotropy

occurs when a single gene affects multiple traits

polygenic inheritance

when a single trait is controlled by multiple genes, each contributing to the phenotype in additive/quantitive manner

ex) height, skin color

epistasis

one gene masks/modifies the effect of another gene at a different locus

ex) pea flower color

c gene- produces pigment

p gene- determines if pigment is shown

environmental influence

environmental factors affect gene expression and phenotypic outcomes

multifactorial

traits determined by the combined effects of multiple genes (polygenic) and environmental factors