Dominance

Dominance refers to the phenomenon in genetics where the effect of one allele masks the contribution of a second allele at the same locus. In simpler terms, it is the situation where one allele is responsible for the phenotype, while the other has no noticeable effect.

Genetic Dominance

In the field of genetics, dominance describes the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from their parents. If the two alleles are different, dominant alleles are those that are expressed, or seen, while recessive alleles are those that are hidden, or not seen.

Types of Dominance

There are three types of dominance: complete dominance, co-dominance, and incomplete dominance.

Complete Dominance

In complete dominance, the dominant allele completely masks the effect of the recessive allele in the heterozygous condition. This is the most common form of dominance.

Co-Dominance

In co-dominance, both alleles are fully expressed in the phenotype of the heterozygote. This results in phenotypes that are a combination of both alleles.

Incomplete Dominance

In incomplete dominance, the phenotype of the heterozygotes is intermediate between the phenotypes of the two homozygotes. This means that neither allele is completely dominant over the other.

Examples of Dominance

Dominance is a key concept in Mendelian inheritance and explains why an organism with a heterozygous genotype expresses the phenotype associated with the dominant allele. An example of this is the inheritance of flower color in pea plants.

See Also

• Genetics
• Allele
• Mendelian inheritance
• Complete dominance
• Co-dominance
• Incomplete dominance

Dominance Resources
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