Download Pre AP - Applications of Genetics Notes Incomplete dominance and

Pre AP - Applications of Genetics Notes
Incomplete dominance and Codominance

When one allele is NOT completely ____________ over another (they ______) – ___________________
Example: In carnations the color red (R) is incompletely dominant over white (r). The hybrid color is
pink. Give the genotypic and phenotypic ratio from a cross between 2 pink flowers.
_____ X _____
RR = red
rr = white
Genotypic =
Rr = pink
______ : ______ : ______
Phenotypic = _______ : ________ : _________

When _______ alleles are _____________ – ___________________
Example: In certain species of chickens black feathers (FB) are codominant with white feathers (FW).
Heterozygous chickens have black and white speckled feathers. Show the F1 from crossing
2 hybrid chickens. Give the genotypic and phenotypic ratio.
FBFB = black
FWFW = white
FBFW = speckled
_________ X _________
Genotypic =
__________ : __________ : __________
Phenotypic = _________ : ______________ : _________
Sex – linked Traits

________ for these ________ are located ______ on the ___ chromosome (NOT on the Y chromosome)

X linked alleles _________ show up in _________ whether _______________ or ______________
because males have only ______ X chromosome
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
Examples of _____________ sex-linked disorders:
1. ___________________ – inability to distinguish between certain colors (most common red/green)
2. ___________________ – blood won’t clot (blood clotting factor VIII defective)
3. __________________________________ --wasting away of skeletal muscles

Example: A female that has normal vision but is a carrier for colorblindness marries a male with normal
vision. Give the expected phenotypes of their children.
N = normal vision
n = colorblindness
________ X _________
Phenotype: ______________________
______________________
______________________
______________________
Pedigrees


____________ representation of how a ________ is passed from parents to ________________
Tips for making a pedigree
1. __________ are for females
2. __________ are for males
3. _______________ ________ connecting a male and a female represent a ______________
4. _____________ ________ and _____________ connect parent to offspring
5. A ____________ circle or square indicates a person _____ the trait
6. A circle or square ______ ___________ represents an individual who does NOT have the trait
7. __________ shade indicates a ___________ – someone who is _________________ for the trait

Example: Make a pedigree chart for the following couple. Dana is color blind; her husband Jeff is not.
They have two boys and two girls. HINT: colorblindness is a recessive sex-linked trait
______
Has trait
______
Can pass trait
2 to
offspring
Multiple Alleles

___ ___ _______ ___________ of the ________ gene that code for a _________ trait

In humans, _________ ______ is determined by 3 alleles – ____, ____, and ____
BUT genes come in pairs, so each human can only ________ ___ alleles
1. Codominant – _________________
Recessive – __________
2. Blood type – A =
B=
AB =
O=

Example: A woman homozygous for type B blood marries a man who is heterozygous type A. What will
be the possible genotypes and phenotypes of their children?
_____ X _____
Genotypic =
____________ : ____________
Phenotypic = _________ : __________

Blood types used for paternity and crime scene investigations before DNA evidence
Polygenic Inheritance

Effect of _________________________________ on a single phenotypic characteristic

Examples: ____________________________________________________________________

Skin color: dark is dominant to light, genes are not linked
Ex: aabbcc = very light
AABBCC = very dark
AaBbCc =
AABbcc =

Disorders that are polygenic: ___________________________________________________
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Mutations


Mutation – sudden ___________ _________ (change in ______ pair sequence of ______)
Can be :
____________ mutations – organism ______ ______ to survive: genetic disorders, cancer, death
5-8 genes in humans results in death – lethal mutation
____________ mutations – allows organism to _______ ________: provides __________ ___________
____________ mutations – __________ harmful nor helpful to organism


Mutations can occur in 2 ways: _________________ mutation or __________________ mutation
Only mutations in ____ _________ are passed from parent to ______________________
Chromosomal mutation:

______ ___________ than a gene mutation

more __________ – affects entire _______________, so affects _______ ________ rather than just one

caused by failure of the _______________ chromosomes to ____________ normally during __________

___________________________ no longer look the same – too few or too many genes, different shape

Examples:
_________ syndrome – (Trisomy 21) ____ chromosomes, extra chromosome at pair ______
_____________ syndrome – only ____ chromosomes, missing a _____ chromosome (X)
__________________ syndrome – ____ chromosomes, _______ ____ chromosomes (XXY)
Gene or Point Mutation

_______ __________ and ________ ____________

usually only ______ ________ is altered

Examples:
Recessive gene mutations:
________ ______ _________ – ______ ________ _______ are sickle shaped instead of round and get
stuck in the blood vessels – can cut off blood supply to organs –
heterozygous condition protects people from _____________
___________ __________ – __________ clogs lungs, liver and pancreas
_______________ ___________ – deterioration of the ___________ ___________ – early death
_____________________(PKU) – an _______ _____ common in ______ cannot be broken down and as
it builds up it causes _________ ____________ – newborns are tested
for this
Dominant gene mutations:
_______________ __________ – gradual _______________ of ________ _________, shows up in
_________ _____ and is _______
_______________ – variety of ____________ abnormalities
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