Chapter Two: Extensions to Mendel Flashcards
dominance is not always ___
complete
crosses between true-breeding strains can produce hybrids with phenotypes ___ from both parents
different
F1 hybrids that differ from both parents express an intermediate phenotype
incomplete dominance
F1 hybrids express phenotype of both parents equally
codominance
in incomplete dominance and codominance, phenotypic ratios and genotypic ratios are ___
the same
snapdragon flower color is an example of ___
incomplete dominance
lentil coat pattern is an example of ___
codominance
ABO Blood group is an example of ___
codominance
dominance relations affect ___ and have no bearing on the ___ of alleles
phenotype
segregation
alleles still segregate ___ even without incomplete dominance
randomly
can a gene have more than two alleles
yes
genes may have ___ alleles that segregate
multiple
although there can be many alleles in a population, each individual carries ___
only two of the alleles
there are ___ alleles for blood type and ___ possible genotypes that generate ___ possible phenotypes
three
six
four
dominance relations are ___ to a certain pair of alleles
unique
in order to establish dominance relations, you perform ___ between ___ of al phenotypes
reciprocal crosses
pure-breeding lines
where do new alleles come from
mutations
multiple alleles arise spontaneously from ___
mutations
chance alterations in genetic material
mutations
the percentage of the total number of gene copies represented by one allele
allele frequency
allele whose frequency is more than 1%
wild-type
allele whose frequency is less than 1%
mutant allele
gene with only one wild-type allele
monomorphic
gene with more than one wild-type allele
polymorphic
one gene may contribute to ___
several visible characteristics
when a single gene determines more than one distinct and seemingly unrelated characteristic
pleiotropy
a syndrome is defined as something that has many symptoms because ___
multiple organ systems are impacted by the disease
type of pleiotropy where alleles produce a visible phenotype and affect viability
lethality
alleles that produce viability often produce deviations from typical ___ predicted by mendel’s laws
ratios
inheritance of coat color in mice is an example of ___
pleiotropy
recessive lethal alleles are not as ___ as other alleles because ___, changes the ___
viable
progeny normally don’t survive until birth
ratio
more than ___ mutant alleles have been identified so far for sickle cell
400
normally wild type allele for sickle-cell ___
HbBA
HbBS allele specifies for an abnormal protein that causes ___
sickling along red blood cells
the most common mutant allele for sickle-cell substitutes an amino acid with a ___ for one with a ___, which changes its ___
negative charge
neutral charge
shape
HbBS affects more than one ___
trait
the advantage of heterozygotes for sickle-cell
resistant to malaria
it is difficult to get rid of a ___ when carriers have an advantage
deleterious allele
___ can emerge from the combination of alleles of two genes
novel phenotypes
two genes work together to produce a phenotype
complementary gene action
___ ratio is a phenotypic signature of complementary gene interaction where dominant alleles of two genes act together to produce a trait while the other three genotypic classes do not
9:7
a 9:7 ratio demonstrates that ___ must be present to produce a trait
one dominant allele of each gene
when one gene’s allele mask the effects of another gene’s alleles
epistasis
Labrador retriever coat color is an example of ___
recessive epistasis