Types of Traits

Incomplete Dominance vs. Co-dominance


Incomplete dominance is an intermediate type of inheritance. Once allele for a specific trait does not completely dominate over the other allele. Because of this, a new type of phenotype is created. This phenotype expresses a physical trait that is a combination of the dominant and recessive physical trait.

An example of incomplete dominance is shown the breeding of a red flower x a white flower:

The red or white don't dominate over each other. Instead they produce a mixture of the both: pink. However when the F1 pink flowers are crossed with each other they produce every possible combination.

The incomplete dominance trait is also shown in blood types. Instead of A dominating over B, or vice versa, it creates a new type of blood: AB. Also, people that show phenotypes for A or B blood can still be carriers for O. This is how two parents that may be A and B can produce a child that is the O blood type.

Genotype	Phenotype
IOIO	Type O
IAIO	Type A
IAIA	Type A
IBIO	Type B
IBIB	Type B
IAIB	Type AB

Co-dominance is a condition in which the alleles of a gene pair in a heterozygot are both fully expressed. This results in a offspring that doesn't have either a dominant or recessive genotype.