14.2 Flashcards
Heritable characters
Not determined by only one gene with two alleles
Complete dominance
Occurs when phenotypes of the heterozygous
Incomplete dominance
The phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
Codominance
Two dominant alleles affect the phenotype in separate distinguishable ways
Alleles are simply variations in a gene’s what?
Nucleotide sequence
Dominance/recessiveness relationships of alleles depend on the level of which we examine what?
Phenotype
Tay-Sachs disease
Fatal, dysfunctional enzyme causes an accumulation of lipids in the brain
Frequency of Dominant Alleles
Dominant alleles are not necessarily more common in populations that recessive alleles
Multiple alleles
Most genes exist in populations in more than two allelic forms
Pleiotropy
Most genes have multiple phenotypic effects
Epistasis
A gene at one locus that alters phenotypic expression of a gene at a second locus
Quantitative characters
Those that vary in the population along a continuum
Polygenic inheritance
An additive effect of two or more genes on a single phenotype
What is an example of polygenic inheritance?
Skin color
