Incomplete Dominance & Codominance

Flashcards on Incomplete Dominance & Codominance

Non-Mendelian Inheritance

Monohybrid crosses that do not follow strict laws of Mendelian inheritance.

Incomplete Dominance

The F1 hybrids have an appearance that's in between the phenotypes of two parental varieties.

Snapdragons

Example of incomplete dominance; red (RR) x white (rr) yields pink (Rr).

Incomplete Dominance Result

Genotype: 100% Rr, Phenotype: 100% Pink.

Identifying Incomplete Dominance

If you notice three colors in a genetic problem, it's most likely an incomplete dominance problem.

Codominance

Two alleles are expressed in heterozygous individuals (two dominant alleles, no recessive allele).

Codominance vs. Mendelian Traits

Under normal Mendelian traits, there is one dominant and one recessive allele; in codominance, there are two dominant alleles.

Non-Mendelian Inheritance

Monohybrid crosses that do not follow strict laws of Mendelian inheritance.

Incomplete Dominance

The F1 hybrids have an appearance that's in between the phenotypes of two parental varieties.

Snapdragons

Example of incomplete dominance; red (RR) x white (rr) yields pink (Rr).

Incomplete Dominance Result

Genotype: 100% Rr, Phenotype: 100% Pink.

Identifying Incomplete Dominance

If you notice three colors in a genetic problem, it's most likely an incomplete dominance problem.

Codominance

Two alleles are expressed in heterozygous individuals (two dominant alleles, no recessive allele).

Codominance vs. Mendelian Traits

Under normal Mendelian traits, there is one dominant and one recessive allele; in codominance, there are two dominant alleles.

ABO Blood Groups

Human ABO blood groups are an example of codominance.

ABO Blood Group Alleles

Alleles: I^A, I^B, i

Function of Enzyme (I)

The enzyme (I) adds A or B carbohydrates to red blood cells.

The i allele results

Non-Mendelian Inheritance

Monohybrid crosses that do not follow strict laws of Mendelian inheritance.

Incomplete Dominance

The F1 hybrids have an appearance that's in between the phenotypes of two parental varieties.

Snapdragons

Example of incomplete dominance; red (RR) x white (rr) yields pink (Rr).

Incomplete Dominance Result

Genotype: 100% Rr, Phenotype: 100% Pink.

Identifying Incomplete Dominance

If you notice three colors in a genetic problem, it's most likely an incomplete dominance problem.

Codominance

Two alleles are expressed in heterozygous individuals (two dominant alleles, no recessive allele).

Codominance vs. Mendelian Traits

Under normal Mendelian traits, there is one dominant and one recessive allele; in codominance, there are two dominant alleles.

ABO Blood Groups

Human ABO blood groups are an example of codominance.

ABO Blood Group Alleles

Alleles: I^A, I^B, i

Function of Enzyme (I)

The enzyme (I) adds A or B carbohydrates to red blood cells.

Function of allele i

The i allele results in no carbohydrate being added to red blood cells.

Genotype of type A blood

Individuals with blood type A have this genotype.

Individuals with blood type B have this genotype.