Download Ch. 11.3 Other Patterns of Inheritance

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• One allele is not completely dominant over the
other.
- heterozygous phenotype always intermediate
Ex.
A cross between a recessive white flowered
four o’ clock plant (rr) and a homozygous
dominant red flowered four o’ clock plant (RR).
• Phenotypes of both alleles are completely
expressed.
Ex.
A cross between a white feathered
chicken (bb) and a black feathered male
chicken (BB).
• A gene that has a trait with two or more
alleles.
- Many genes exist this way (blood typing)
Ex. Rabbit coat color
Phenotype
Allele
Pattern of Inheritance
Dark Gray Coat
C
Dominant to all other
alleles
Chinchilla
cch
Dominant to Himalayan
and white
Himalayan
ch
Dominant to white
White
c
Recessive
• Traits controlled by more than two genes.
Ex. Skin color, height
• Environment can affect the expression of genes
and influence genetically determined traits.
Ex.
Temperature dependent sex determination
in reptiles