L3 Extensions of Mendelian Genetics Flashcards
incomplete dominance
expression in a heterozygote that allows it to be distinguished from both homozygous genotypes
“blend” but actually is just partial expression not full expression
pink flower from red and white
co-dominance
expression in a heterozygote that is distinct from both parents
both phenotypes are expressed
implies ALLELE INDEPENDENCE
cow coat color, white and brown making a white with brown spots
what is an allelic series?
it describes the dominance hierarchy of multiple alleles
what is a complementation test and what does it do?
its a cross between mutants to see what happens
works with RECESSIVE phenotypes
results:
end with mutant type = alleles of same gene
end with wildtype = alleles of different genes
broken bike + flat tire = functional bike by scraping for parts
broken bike + broken bike = nonfunctional bike
epistasis
where an allele of one gene OVERIDES the effect of other genes on the phenotype
baldness gene masks hair color so observed trait is bald
pleiotropy
where a gene affects multiple phenotypes
white gene in cats can result in blue eyes and deafness
how does protein alteration affect genotype?
it effects the severity of genotype and if it is dominant or recessive
recessive mutations often diminish polypeptide activity in which condition? (homo/hetero)
homozygous condition
what do phenotypes depend on?
environmental and genetic factors
penetrance
a trait shows incomplete penetrance in cases where an individual does not show the trait even though they have the appropriate phenotype
expressivity
where a trait is not uniformly expressed in the individuals that have it
variable penetrance and expressivity
cases where not every individual with the genotype shows the trait, and those that do can show it to a varying degree
polydactyly: penetrance or expressivity?
incomplete penetrance of a dominant trait
do not express it even if they have the appropriate genotype
lobe eye mutation of flies: penetrance or expressivity?
variable expressivity, a trait is not manifested uniformly among individuals that show it.
does inbreeding reduce or increase genetic diversity?
REDUCES diversity because it increases the number of loci that are homozygous
can reveal recessive phenotypes
