Chapter Two: Extensions to Mendel Flashcards
1
Q
dominance is not always ___
A
complete
2
Q
crosses between true-breeding strains can produce hybrids with phenotypes ___ from both parents
A
different
3
Q
F1 hybrids that differ from both parents express an intermediate phenotype
A
incomplete dominance
4
Q
F1 hybrids express phenotype of both parents equally
A
codominance
5
Q
in incomplete dominance and codominance, phenotypic ratios and genotypic ratios are ___
A
the same
6
Q
snapdragon flower color is an example of ___
A
incomplete dominance
7
Q
lentil coat pattern is an example of ___
A
codominance
8
Q
ABO Blood group is an example of ___
A
codominance
9
Q
dominance relations affect ___ and have no bearing on the ___ of alleles
A
phenotype
segregation
10
Q
alleles still segregate ___ even without incomplete dominance
A
randomly
11
Q
can a gene have more than two alleles
A
yes
12
Q
genes may have ___ alleles that segregate
A
multiple
13
Q
although there can be many alleles in a population, each individual carries ___
A
only two of the alleles
14
Q
there are ___ alleles for blood type and ___ possible genotypes that generate ___ possible phenotypes
A
three
six
four
15
Q
dominance relations are ___ to a certain pair of alleles
A
unique
16
Q
in order to establish dominance relations, you perform ___ between ___ of al phenotypes
A
reciprocal crosses
pure-breeding lines
17
Q
where do new alleles come from
A
mutations
18
Q
multiple alleles arise spontaneously from ___
A
mutations
19
Q
chance alterations in genetic material
A
mutations
20
Q
the percentage of the total number of gene copies represented by one allele
A
allele frequency
21
Q
allele whose frequency is more than 1%
A
wild-type
22
Q
allele whose frequency is less than 1%
A
mutant allele
23
Q
gene with only one wild-type allele
A
monomorphic
24
Q
gene with more than one wild-type allele
A
polymorphic
25
one gene may contribute to ___
several visible characteristics
26
when a single gene determines more than one distinct and seemingly unrelated characteristic
pleiotropy
27
a syndrome is defined as something that has many symptoms because ___
multiple organ systems are impacted by the disease
28
type of pleiotropy where alleles produce a visible phenotype and affect viability
lethality
29
alleles that produce viability often produce deviations from typical ___ predicted by mendel's laws
ratios
30
inheritance of coat color in mice is an example of ___
pleiotropy
31
recessive lethal alleles are not as ___ as other alleles because ___, changes the ___
viable
progeny normally don't survive until birth
ratio
32
more than ___ mutant alleles have been identified so far for sickle cell
400
33
normally wild type allele for sickle-cell ___
HbBA
34
HbBS allele specifies for an abnormal protein that causes ___
sickling along red blood cells
35
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
36
HbBS affects more than one ___
trait
37
the advantage of heterozygotes for sickle-cell
resistant to malaria
38
it is difficult to get rid of a ___ when carriers have an advantage
deleterious allele
39
___ can emerge from the combination of alleles of two genes
novel phenotypes
40
two genes work together to produce a phenotype
complementary gene action
41
___ 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
42
a 9:7 ratio demonstrates that ___ must be present to produce a trait
one dominant allele of each gene
43
when one gene's allele mask the effects of another gene's alleles
epistasis
44
Labrador retriever coat color is an example of ___
recessive epistasis
45
labrador retrievers:
B allele is ___ and determines ___
b allele is ___ and determines ___
E allele is ___ and determines ___
e allele is ___ and determines ___
dominant, black
recessive, brown if homozygous
on a second gene, no effect
recessive, hides brown or black is homozygous
46
9:3:4 is a telltale ratio of ___
recessive epistasis
47
the expected phenotypic ratio for recessive epistasis of lab coat color is ___
9 black (B_E_): 3 brown (bbE_): 4 gold (__ee)
48
epistasis in human blood groups: two parents who are apparently O can have offspring that are ___ because of the ___
type A or B on occasion
bombay phenotype
49
the Bombay phenotype is a ____ at a ___ that masks the phenotype of ___ if it is homozygous recessive
mutant recessive allele
second gene
ABO alleles
50
presence of dominance allele at second gene hides the affects of alleles at an original gene
dominance epistasis
51
12:3:1 and 13:3 are telltale ratios for ___
dominance epistasis
52
it is not always possible to determine ____ mutated in a person with a heterogenous mutant phenotype
which of many genes
53
deafness in humans may be caused by a mutant allele at one of more than ___ different genes
50
54
___ can determine if mutations arise from the same or different genes
complementation testing
55
human deafness: if parents have a defect in the same gene, their offspring will ___. if parents have a defect in different genes, their offspring will ___.
all be deaf
possibly be hearing
56
four distinct F2 phenotypes
additive
57
when homozygous, recessive allele of one gene masks both alleles of another gene
recessive epistasis
58
when homozygous, recessive allele of each gene masks the dominant allele of the other gene
reciprocal recessive epistasis
59
dominant allele of one gene hides effects of both alleles of the other gene
dominant epistasis I
60
dominant allele of one gene hides effects of dominant allele of another gene
dominant epistasis II
61
only one dominant allele of either of two genes is necessary to produce phenotype
redundancy
62
how do we know if a trait is caused by one gene or two genes that interact
ratios like 9:7 or 13:3 indicate gene interaction
look at different ratios to determine which is correct
63
additive gene interaction ratio
9:3:3:1
64
recessive epistasis ratio
9:3:4
65
reciprocal recessive epistasis ratio
9:7
66
dominant epistasis I ratio
12:3:1
67
dominant epistasis II ratio
13:3
68
redundancy ratio
15:1
69
disease that produces little or not pigmentation in skin, hair, and eyes
ocularcutaneous albanism (OCA)
70
the same genotype doesn't always produce ___
the same phenotype
71
phenotype often depends on ___ and ___
penetrance and expressivity
72
percentage of a population with a particular genotype that show the expected phenotype
penetrance
73
penetrance can be ___ or ___
complete or incomplete
74
degree or intensity with which a particular genotype is expressed in a phenotype
expressivity
75
have subtle, secondary effect on a phenotype from a major gene
modifier genes
76
environment can affect the ___ of a genotype
phenotypic expression
77
___ is a common element of the enrichment that affects phenotype
temperature
78
example of temperature impacting phenotype
coat color in siamese cats is darker in its extremities (legs, tail, ears)
79
why do the colors differ in siamese cats
mutation that renders an enzyme involved in melanin synthesis is temperature sensitive
80
change in phenotype arising from environmental agents that mimics the effect of a mutation at a gene
phenocopy
81
mutations that are lethal only under some conditions
conditional lethal
82
mutant allele has wild-type functions (normal)
permissive conditions
83
mutant allele has defective functions
restrictive conditions
84
traits determined by segregating alleles of many genes interacting with one another and the environment
continuous traits
85
example of continuous traits in humans
height and skin color
86
continuous traits are also called ___ and are usually ___
quantitative traits
polygenic
87
the more genes that contribute to a trait, the greater number of ___ and the greater similarity to ___
possible phenotypes
continuous variation
88
continuous variation phenotypic rations will exhibit a ___
bell curve
89
domestic dog coat colors provide a clear example of a ___
complex trait
90
there are at least ___ genes that control for coat color and pattern in dogs
12
91
skin cells that produce pigments deposited in each dog hair
melanocytes
92
melanocytes can produce either ___ or ___
dark pigment (eumelanin) or light pigment (pheomelanin)
93
genes E, A, and K control ___
the switch between light and dark pigment synthesis in melanocytes
94
genes E and B control ___
synthesis and deposition of the dark pigment eumelanin
95
genes S and M control ___
spotting
96
the F1 phenotype generated by a pair of alleles defines the ___ between alleles
dominance relationship
97
incomplete dominance: F1 resembles ___
codominance: F1 resembles ___
neither parent
components of each parent
98
one gene can contribute to ___
multiple traits
99
a single gene may have many ___
alleles
100
new alleles arise by ___
mutation
101
wild type alleles ___ 1% of the population. mutant alleles ___ 1% of the population
more then
less then
102
two or more wild type alleles in the population
polymorphic gene
103
a gene with only one wild type allele
monomorphic
104
two or more genes may interact to produce a ___
phenotype
105
when the action of an allele at one gene hides traits normally caused by alleles at another gene
epistasis
106
when dominant alleles of two or more genes are required to generate a trait
complementary gene action
107
with ___, mutant alleles at any one of two or more genes are sufficient to elicit a phenotype
heterogeneity
108
___ can reveal whether a particular phenotype arises from mutations in the same or separate genes
complementation tests
109
expression of phenotypes can be modified by ___, ___, or ___
environment, chance, or other genes
110
when fewer than 100% of individuals with the same genotype express a specific phenotype
incomplete penetrance
111
a phenotype may show ___ when it is expressed at a different level in different individuals with the same genotype
variable expressivity
112
a ___ trait can have any value of expression between two extremes, most are ___
quantitative
polygenic
