Differences between Dominant and Recessive
Dominant vs. Recessive[edit]
In genetics, dominant and recessive refer to the relationship between different versions, or alleles, of a gene.[1] Each individual inherits two alleles for each gene, one from each parent.[2] The interaction of these alleles determines how a specific trait is expressed. A dominant allele will determine the physical characteristic, or phenotype, even if only one copy is present. A recessive allele, in contrast, will only be expressed as a trait if two copies are present.[3]
The concepts of dominance and recessiveness are central to Mendelian inheritance. A dominant allele is expressed in individuals who have one or two copies of that allele. For example, the allele for brown eyes is dominant.[4] If an individual inherits one allele for brown eyes and one for blue eyes, they will have brown eyes because the brown eye allele masks the effect of the blue eye allele.[4] In genetic notation, a dominant allele is typically represented by a capital letter.[5]
A recessive allele is only phenotypically expressed when an individual has two copies of it.[3] If an individual inherits one recessive allele and one dominant allele, they will be a "carrier" of the recessive trait, but the trait will not be visible.[1] The allele for blue eyes is recessive, meaning a person must inherit two copies of the blue-eye allele to have blue eyes. A recessive allele is usually denoted by a lowercase letter.[5]
Certain genetic disorders are inherited as dominant or recessive traits. Huntington's disease, for instance, is caused by a dominant allele, meaning an individual only needs to inherit one copy of the defective gene to develop the disorder.[3] Cystic fibrosis, on the other hand, is a recessive disorder, requiring an individual to inherit two copies of the faulty allele to be affected.[1]
Comparison Table[edit]
| Category | Dominant | Recessive |
|---|---|---|
| **Alleles Required for Expression** | One | Two[3] |
| **Effect in Heterozygous Condition** | The dominant trait is expressed | The trait is not expressed, but the individual is a carrier[1] |
| **Representation** | Capital letter (e.g., A)[5] | Lowercase letter (e.g., a)[5] |
| **Example Trait** | Brown eyes[4] | Blue eyes |
| **Example Genetic Disorder** | Huntington's disease[3] | Cystic fibrosis[1] |
References[edit]
- ↑ 1.0 1.1 1.2 1.3 1.4 "yourgenome.org". Retrieved December 13, 2025.
- ↑ "study.com". Retrieved December 13, 2025.
- ↑ 3.0 3.1 3.2 3.3 3.4 "patsnap.com". Retrieved December 13, 2025.
- ↑ 4.0 4.1 4.2 "study.com". Retrieved December 13, 2025.
- ↑ 5.0 5.1 5.2 5.3 "betterhealth.vic.gov.au". Retrieved December 13, 2025.
