Download Fill-in notes - Liberty Union High School District

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Name___________________________________
Genetics Part 2: Incomplete & Codominance
Classic Dominance: (aka “___________________ dominance”) the _______________________ displays the
_______________________ phenotype
Ex) Purple Flower (PP) x White Flower (pp)  Purple Flower (Pp)
Incomplete Dominance
 Incomplete Dominance: occurs when offspring have a phenotype that is ________________________ the
two parent phenotypes.
- Heterozyote displays a _______________ phenotype (dominant no longer masks recessive!)
EXAMPLE: Four O’ Clock Flowers
Find the phenotypes for the following genotypes and use them to complete the Punnett squares below.
Genotype
RR
Phenotype
rr
Rr
Square 1: Cross Rr with Rr
Square 2: Cross RR with rr
Square 3: Cross RR with Rr
Genotypic Ratio: ______________
Genotypic Ratio: ______________
Genotypic Ratio: ______________
Phenotypic Ratio:
Phenotypic Ratio:
Phenotypic Ratio:
____________________________
____________________________
____________________________
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CODOMINANCE FILL-IN NOTES
X
CODOMINANCE:



=
both alleles are ____________ in a heterozygote.
Neither allele is ____________________________________
Both show up in the ________________________. There is no ___________________________ like in
incomplete dominance.
Examples: ___________________________________________________________________________
SPECIAL CASE! How to write genotypes for codominant alleles
Notation:
 Use with codominance only
 Example: Codominance in
cow coat colors
 WRITE IN WHAT THE
LETTERS REPRESENT
CR
CODOMINANCE EXAMPLE: Roan Coat Color in Cattle
Genotype
Phenotype
Show a cross between a red bull and a roan cow.
(write the parent genotypes on the line below)
______________ X ______________
Genotypic ratio: ________________________________
Phenotypic ratio: ________________________________________
CODOMINANCE EXAMPLE: Blood Types




There are ____ alleles for blood genotypes: _____, ______, ______
There are 4 blood phenotypes: _____, _____, _____, _____
_____ and _____ are codominant; both are expressed in type AB blood.
Type _____, which has genotype _____ is recessive to
both _____ and _____.
You aren’t done yet! Be sure to copy the Blood Type Example into
your notebook and do your summary!
Genotype
Phenotype
IAIA or IAi
Type _______
IBIB or IBi
Type _______
ii
Type _______
IAIB
Type _______