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SBI3U – Genetic Processes
81902407
Beyond Mendelian Genetics
Mendelian Genetics
Mendel found that inherited traits were either ________________ or ____________
Dominant allele always being expressed
Mendel was lucky
Peas are genetically _______________
Most traits are controlled by a _________________ gene
Each gene has only ___ alleles, 1 of which is completely ___________________
to the other
The relationship between genotype & phenotype is rarely that simple
Incomplete Dominance
In incomplete dominance, ___________________ of traits can be seen
Get ___________________ results in ____________________ individuals
Happens frequently in ___________
White and red snap dragons are _________________________
When you breed the white with red, you get __________
Not enough _________________ to make red flowers with only one red allele
Must use the same ____________ because we are talking about the same
__________________________
Use ____ for red
Use ____ for white
Example: The Scarlet Tiger moth (Panaxia dominula) can have red wings, yellow
wings, or orange wings. Assume that red wings are expressed from the
homozygous RR genotype, yellow wings from the homozygous R'R' genotype, and
orange wings from the heterozygous genotype. What will be the phenotypic ratio of
the F1 generation resulting from a cross of two orange moths?
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SBI3U – Genetic Processes
81902407
Co-dominance
Occurs when two traits are both _______________
Both alleles are _________________ in the individual
2 alleles affect the phenotype equally & separately
Chicken _____________________ are both dominant (white and black)
Instead of a new combined trait when in the heterozygous state, each of the new
traits are visible
Example: A cross between a black cat & a tan cat produces a tabby pattern (black &
tan fur together). What percent of kittens would have tan fur if a tabby cat is crossed
with a black cat?
Multiple Alleles
Not all traits have only _____ possibilities
Can have _________________________ possibilities, multiple alleles
An individuals can only carry two different alleles for a given gene
Some of the alleles can be _______________ and ________________, while some
can be ______________________
Blood types
A, B, AB, O
IA and IB are ___________________________
IA and IB are ____________________ over i
Example: Suppose a father of blood type A and a mother of blood type B have a
child of type O. What blood types are possible in their subsequent children?
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SBI3U – Genetic Processes
81902407
Example: Suppose a child is of blood type A and the mother is of type O. What type
or types may the father belong to?
Example: Ross has type B blood and his wife Rachel has type A blood. They are
very shocked to hear that their baby, Emma, has type O blood, and think that a
switch might have been made at the hospital. Can this baby be theirs?
Epistasis
One gene completely _____ another gene
Coat colour in mice has 2 separate genes
Coat pigmentation: pigment (C) or no pigment (c)
Coat colour: more pigment (black=B) or less (brown=b)
cc = albino, no matter B allele
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SBI3U – Genetic Processes
81902407
2 genes: (E,e) & (B,b)
pigment (E) or no pigment (e)
pigment concentration: black (B) to brown (b)
Sex Linked Traits
There are genes on the ___ chromosomes as opposed to autosomal chromosomes
First discovered by T.H. Morgan at Columbia University in Drosophila
melanogaster
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SBI3U – Genetic Processes
81902407
In humans, there are 2 sex chromosomes: ___________
2 X chromosomes
Develop as a ________________
Gene _______________________ like autosomal chromosomes
X & Y chromosome
Develop as a _____________
No ____________________________
Y chromosome
__________________________________ region
Master regulator for ___________________
Turns on genes for production of male hormones
X chromosome
Other genes/traits beyond ______________________________________
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