Download Complex Patterns of Inheritance

Incomplete and
Codominance
Simple Inheritance
Mendel studied simple patterns of
inheritance.
 Found that inheritance was controlled by a
dominant allele (B) or recessive allele (b).
 However, there are many inheritance
patterns that are more complex.
 Most traits aren’t simply dominant or
recessive.

“Incomplete Dominance”
-When traits are inherited in an incomplete
dominance pattern, the phenotype of the
heterozygous is a blend of the homozygous
dominant (BB) and the homozygous recessive
(bb).
Example: BB = red
bb = white
Bb = pink
Codominance
-Occurs when both alleles for a gene are
expressed in a heterozygous offspring.
-Neither allele is dominant or recessive; no
blending.
Example- in horses, R is for red coat color, W is for white
coat color. RW= roan coat color.
RR = red, WW= white, RW= roan