• Incomplete Dominance
– One allele is not completely dominant over the other.
– Offspring shows blending phenotype
– Eg: White flower
crosses with a red = pink flower.
Beyond Dominant and Recessive• Codominance
– Both alleles contribute to the phenotype.
– Eg: Red cow X White Cow = Roan Cow.
– Eg: blood type
phenotype A B AB O
IA IA
or
IA i
IB IB
or
IB iIA IB i i
phenotype
genotype
Beyond Dominant and Recessive• Multiple Alleles
– One gene have more than two alleles
– Eg: Rabbit coat color, four alleles: • C > cch > ch> c
– Eg: blood type, three alleles• IA = IB > i
Full
• Polygenic traits
– Several genes control the trait.
– Wide range phenotypes. – Eg: Skin color, height
Beyond Dominant and Recessive
• Sex linkage (x-linked)
– Some genes are present on the X chromosome but missing on the shorter Y chromosome.
Beyond Dominant and Recessive
1) Color blindness
– more common in males than in females.
Beyond Dominant and Recessive
2) Haemophilia
– unable to clot blood