Transcript Males and females can differ in sex-linked traits.

Complex Patterns of Heredity
Males and females can differ in sex-linked
traits.
• Genes on sex chromosomes are called sexlinked genes.
– Y chromosome genes in mammals are responsible
for male characteristics.
– X chromosome genes in mammals affect many
traits
Example of Sex-Linked Traits
Inheriting Sex Linked Traits
• Sex Linked Traits are inherited on the X chromosome.
• How would a male inherit the gene for
colorblindness?
• How could a female be colorblind?
• Who is more likely to display a colorblind trait?
Other Examples: Hemophilia, Baldness, Calico Cats
Incomplete Dominance
• Some traits are neither totally dominant or recessive
• Offspring inherit a trait that is a blend
• Example: red snapdragon x white snapdragon
pink snapdragon
Human Incomplete Dominance
• Example- Sickle Cell Anemia
Multiple Alleles and Codominance
• Many genes have more than two alleles
ex. Blood Type
IA or IB or i
Codominace
Both alleles in a heterozygous match express
themselves fully
– Codominant alleles are neither dominant nor
recessive.
– The ABO blood types result from codominant
alleles.
A pedigree is a chart for tracing genes in a
family
• Phenotypes are used to infer genotypes on a pedigree.
• Autosomal genes show different patterns on a pedigree than
sex-linked genes.
If the phenotype is more common in males,
the gene is likely sex-linked.