Dominant traits

Definition

Dominant traits are characteristics that are expressed in an organism even if only one allele for the trait is present. These traits mask the effects of recessive alleles when both are present.

5 Must Know Facts For Your Next Test

1. Dominant traits are represented by uppercase letters in genetic notation.
2. In Mendel's pea plant experiments, tall stem height (T) was a dominant trait.
3. An individual with at least one dominant allele (e.g., TT or Tt) will express the dominant trait.
4. Dominant traits can be inherited from just one parent if that parent contributes a dominant allele.
5. Heterozygous individuals (Tt) exhibit the dominant phenotype.

Review Questions

• What type of letter represents a dominant trait in genetic notation?
• How does the presence of a dominant allele affect the expression of a trait?
• Can a person express a dominant trait if they inherit it from only one parent? Explain.

Related terms

Recessive traits: Traits that are masked by dominant traits and require two copies of the allele to be expressed.

Homozygous: Having two identical alleles for a particular gene.

Phenotype: The observable physical or physiological traits of an organism, determined by its genotype.