Principles of Inheritance
Dominant vs Recessive Allele
A dominant allele is the one that shows when two different alleles are present; a recessive allele stays hidden until it is the only kind present.
Dominant allele
The allele whose trait you see in a heterozygote like Tt. Written as a capital letter. It masks the other allele, but it is not stronger or more common, just the one that shows.
Recessive allele
The allele that stays hidden in a heterozygote and shows only when both copies are recessive, like tt. Written as a small letter. It is fully working, just outvoted when a dominant copy is present.
The trap
The big trap is thinking dominant means stronger, better, or more common. It means none of those. It only means the one that shows when both are present. Plenty of dominant traits are rare, and plenty of recessive traits are common. The test: look at the heterozygote (Tt), and whatever shows there is dominant.
Where this connects
This hidden-versus-shown split is exactly what lets a recessive trait skip a generation and reappear later. The allele was never gone, only masked, which is the heart of genotype versus phenotype.
Genotype vs phenotype →Quick check
In a heterozygote (Tt), the trait that appears is controlled by the:
- ARecessive allele
- BDominant allele
- CBoth equally
- DNeither