Gene Interactions Part 2 Flashcards
most ___ reflect the action of many genes that act
sequentially or jointly, and the phenotype can be affected
by alleles that lack complete dominance and the
environment.
phenotypes
is when a characteristic can change gradually, such as a person’s height or weight
continuous variation
Crosses between true-breeding strains
can produce ___ with phenotypes
different from both parents
hybrids
dominance that . Looks like neither parent
incomplete dominance
dominance that Looks like both parents
codominance
the phenotype of the
heterozygous hybrid is usually an
intermediate between the
homozygous parents.
incomplete dominance
segregation of both phenotype and genotype of incomplete dominance is
1:2:1
Alleles contribute different
amounts of functional ____ in incomplete dominance;
total amount determines
phenotypе.
protein
Both alternative traits can be visualized in the F1.
Example: spotted lentil plant crossed to a dotted lentil plant.
F1 hybrids look like both parents.
codominance
is when both alternative traits are expressed in the
F1 of a cross of two pure breeding parents.
codominance
An equal expression of both alleles
codominance
example of co dominance
roan coat in cattle
Some alleles are neither dominant nor
recessive, and many traits are controlled by
multiple alleles or multiple genes.
t/f
true
The expression of a trait involves more than two
alleles
multiple alleles
example of multiple alleles expressing one trait
ABO blood group
- When heterozygote exceeds the
phenotypic measurements of the
homozygous parents
overdominance
Considering the position of the homozygous dominant
and recessive parents in the figure below, indicate the
location of the heterozygote if the following dominance
relationships are observed
A) Co-dominance
AA (homozygous dominant) –
Aa (heterozygote, co-dominant) – aa (homozygous recessive)
B) Complete dominance
Considering the position of the homozygous dominant
and recessive parents in the figure below, indicate the
location of the heterozygote if the following dominance
relationships are observed
AA (homozygous dominant) –
Aa (heterozygote, complete dominance) –
aa (homozygous recessive)
C) Over dominance
Considering the position of the homozygous dominant
and recessive parents in the figure below, indicate the
location of the heterozygote if the following dominance
relationships are observed
AA (homozygous dominant) –
Aa (heterozygote, overdominance) – aa (homozygous recessive)
D) Incomplete dominance
Considering the position of the homozygous dominant
and recessive parents in the figure below, indicate the
location of the heterozygote if the following dominance
relationships are observed
AA (homozygous dominant) –
Aa (heterozygote, incomplete dominance) –
aa (homozygous recessive)
The product of both alleles (A and a) are expressed
hence it is in between the AA and aa
co-dominance
The presence of a dominant allele in the Aa
would mean expressing the dominant trait.
complete dominance
The Aa could exceed either AA or aa.
overdominance
– The Aa is intermediate.
incomplete dominance
Genes of the same cells are
located on the same nucleus
non-allelic interaction or gene interaction
Considers the possibility that an
allele of a gene could interact with
or alter the expression of the allele
of another gene
non allelic interaction
*2 genes 1 phenotype
additive gene action
___ in genetics refers to a phenomenon where two different mutations in the genome that individually cause a mutant phenotype, when combined in a heterozygote, result in a wild-type (normal) phenotype. This typically occurs when the mutations are in different genes, and each gene provides what the other lacks, thereby “complementing” each other.
complementation
- There is complete dominance in both gene pairs.
New phenotypes are formed from the interaction between
dominant genes and interaction between recessive genes.
novel phenotype
One gene’s allele masks the phenotype of the other
gene’s alleles.
epistasis
Four genotypic classes produce fewer than four
phenotypes.
epistasis
different types of epistasis
recessive epistasis
dominant epistasis
when the recessive allele of
one gene masks the effects of either allele of the
second gene.
recessive epistasis
when the dominant allele of
one gene masks the effects of either allele of the
second gene
dominant epistasis
Appears like
incomplete
dominance because
some of the progeny
look like neither
parent, but the ratio
is wrong.
recessive epistasis
a recessive mutation in one gene masks the phenotypic effects of another
recessive epistasis
You can tell
this genotype is caused by more than one gene because there
are 4 phenotypes not 3 in F2 (9:3:3:1)
2 genes 1 phenotype (additive gene action)
one good copy of each gene
is needed for expression of the final phenotype (9:7 ratio)
complementary gene action
one gene can mask the effect of another gene
epistasis
ratio for recessive epistasis
9:3:4
ratio of dominant epistasis
12:3:1
only double mutant phenotype (15:1 ratio)
duplicate gene
Each genotype results
in a unique phenotype (ratio of 9:3:3:1)
additive gene interaction
At least one dominant
allele from each of two
genes needed for phenotype (ratio is 9:7)
complementary
Homozyous recessive
genotype at one locus masks
expression at second locus (9:3:4)
recessive epistasis
Dominant allele at one
locus masks expression
at second locus
(12:3:1)
dominant epistasis
One dominant allele from
either of twogenes needed
for phenotypе (15:1)
duplicate genes
genotype does not necessarily define phenotype, the proportion of individuals with a given phenotype express the phenotype determine the ___
penentrance
the degree or intensity with which a particular genotype is expressed in a phenotype in a given individual
epxressivity
some both eyes affected, some only one
retinoblastoma
One gene may contribute towards several visible
characteristics.
pleiotrophy
In addition to coat color, a specific allele at this
locus also causes lethality.
pleiotropy
The phenomenon of a single gene determining
multiple distinct traits is known as
pleiotropy
examples of pleiotropy
recessive lethal alleles
sickle cell syndrome
Hereditary congenital deafness in dogs (and cats) is
*associated with defects in ___ ___ cells
neural crest
Hereditary congenital deafness in dogs (and cats) is
*associated with defects in neural crest cells
⚫which are precursors for both
melanocytes
⚫required for pigmentation of the coat and eyes
melanocytes
they have a subtle, secondary effect which
alters the phenotypes produced by the primary genes.
modifier genes
The environment may influence
the effect of a genotype on the phenotype.
modifying environment
The environmental influence of a genotype on the phenotype=
phenocopу
modifying environment
an individual showing features characteristic of a genotype other than its own, but produced environmentally rather than genetically.
phenocopy
The degree to which an allele is expressed may depend
on the environment.
➢ Some alleles are heat-sensitive, for example.
environmental effects
Traits influenced by such alleles are more sensitive to
temperature or light than are the products of other
alleles
environmental alleles
How many gametes will be produced for
the following allele arrangements?
shortcut formula is
2n (n=# of heterozygotes)
How many gametes will be produced for
the following allele arrangements?
RrYy
4 gametes
How many gametes will be produced for
the following allele arrangements?
AaBbCCDd
8 gametes
How many gametes will be produced for
the following allele arrangements?
MmNnOoPPQQRrssTtQq
= 64 gametes
