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Set
Cornell
Notes
on pg.
6.5 up
Traits
and
Probability
75
Patterns
2.17.2
Atoms,
Ions, of Inheritance
and Molecules
•Topic: 7.2 Patterns of
Inheritance
1. Why might polygenic traits vary more in
•Essential Questions:
1. Why might polygenic
traits vary more in
phenotype than do
single-gene traits?
2. How is codominance
the same as having no
dominant and recessive
relationship at all
between 2 alleles?
phenotype than do single-gene traits?
2. How is codominance the same as
having no dominant and recessive
relationship at all between 2 alleles?
KEY CONCEPT
Phenotype is affected by
many different factors.
7.2 Complex Patterns of Inheritance
KEY CONCEPT
Phenotype is affected by many different factors.
7.2 Complex Patterns of Inheritance
+
• What are our possible outcomes for this combination of flower
color?
• What if red nor white was dominant or recessive to one another?
7.2 Complex Patterns of Inheritance
• In incomplete dominance, neither allele is completely
dominant nor completely recessive.
• They are a BLEND of each other
• Ex: red+white rose= pink rose
BB
RR
BR
7.2 Complex Patterns of Inheritance
B
B
BR
BR
BR
BR
R
R
Genotype: BR
Phenotype: 100% pink flowers
7.2 Complex Patterns of Inheritance
B
B
R
R
BB
BR
Red rose
Pink rose
BR
RR
Pink rose
White rose
Genotype:
BB= red RR= white BR= pink
Phenotype: 25%= red flowers
50%= pink flowers 25%= white flowers
7.2 Complex Patterns of Inheritance
• Codominant alleles will both be completely expressed.
– Codominant
alleles are
neither
dominant nor
recessive.
Ex: multi-colored
red and white rose
7.2 Complex Patterns of Inheritance
B
B
BR
BR
BR
BR
R
R
Genotype: BR
Phenotype: 100% red and white flowers
• Polygenic
traits
are produced
by two
7.2
Complex
Patterns
of Inheritance
or more genes.
– Can produce a continuous range
of colors
Ex: Skin color- 4 genes
Eye color- at least 3 genes