chapter three Flashcards
(28 cards)
multifactorial
determined by two or more genes
incomplete dominance
hybrid does not resemble either pure breeding parent
ratio of incomplete dominance
1:2:1
codominant
both traits show up equally in the heterozygotes phenotype
ratio of codominance
1:2:1
multiple alleles
gene may have more than two alleles
dominance series
alleles are listed in order from most dominant to least
mutations
arise spontaneously
allele freq
percentage of total number of gene copies from specific allele
wile type alleles
most common in population +
mutant allele
rare allele in population
monomorphic
a gene with only one common wild type allele
polymorphic
some genes have more that one common allele
common variants
high freq of alleles in polymorphic gene
pleiotropy
phenomenon of a single gene determining a number of distinct and seemingly unrelated characteristics
recessive lethal allele
an allele that negatively affects the survival of a homozygote
ratio of lethal allele
2:1 not 3:1
epistasic
the allele that is doing the mistaking
hypostatic
gene that is being masked
recessive epistasis
homozygosity for a recessibe allele of the second gene is required to hide the effect of another gene, masking effect
dominant epistasis
domninant allele of one gene hides the effects of another gene
penetrance
describe how many members of a population with a particular genotype show the expected phenotype
expressivity
the degree or intensity with which a particular genotype is expressed
modifier genes
subtle secondary effect
alter the phenotypes produced by the alleles of other genes
