Different Types of Crosses
• Incomplete
• Codominance
• Sex-linked
Review: Simple Mendelian Crosses
• Monohybrid
• Dihybrid
Incomplete Dominance
• Neither allele is
dominant.
• The heterozygous is
a MIX of the two
genes.
# 1. Heterozygous parents.
# 1. Heterozygous parents.
Co-dominance
• Both genes are dominant.
• The heterozygous is BOTH.
• Notice that BOTH letters are
used in upper case!
#2. Mother with dominant red scales x
with father with dominant yellow scales.
• What would a heterozygous child look like?
• Oh, this is a snake. 
Sex-linked Traits
• The gene is
located on either
a part of the Y or
X chromosomes
that do not
overlap with each
other.
• Example:
Hemophilia
Sex-linked Traits
• The gene is
located on either
a part of the Y or
X chromosomes
that do not
overlap with each
other.
• Example:
Hemophilia
Incomplete Dominance and
Codominance Interactive Website
• http://www2.edc.org/weblabs/incompletedo
m/incompletedominance.html