Law of Dominance
States that in a pair of contrasting characters, one allele expresses itself (dominant) while the other remains unexpressed (recessive) in the F1 generation.
What is Law of Dominance?
An allele that expresses its phenotypic effect even when only one copy is present in the genotype (in a heterozygous state).
Key points
- To understand the concept of dominance in genetic inheritance.
- To differentiate between dominant and recessive alleles.
- To predict the phenotype of an F1 generation from a cross between pure-breeding parents.
- To explain the reappearance of recessive traits in the F2 generation.
Common exam trap
Confusing genotype with phenotype.
Definitions
- Term
Dominant Allele
- Meaning
An allele that expresses its phenotypic effect even when only one copy is present in the genotype (in a heterozygous state).
- Term
Recessive Allele
- Meaning
An allele whose phenotypic effect is masked by a dominant allele in a heterozygous state and is only expressed when present in a homozygous state.
- Term
Phenotype
- Meaning
The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.
- Term
Genotype
- Meaning
The genetic makeup of an organism; the combination of alleles for a particular gene.
- Term
Heterozygous
- Meaning
Having one dominant allele and one recessive allele for a particular gene (e.g., Tt).
- Term
Homozygous
- Meaning
Having two identical alleles for a particular gene (e.g., TT or tt).
Learning objectives
To understand the concept of dominance in genetic inheritance.
To differentiate between dominant and recessive alleles.
To predict the phenotype of an F1 generation from a cross between pure-breeding parents.
To explain the reappearance of recessive traits in the F2 generation.
Prerequisites
Basic understanding of genetics and heredity.
Knowledge of alleles, genes, and traits.
Familiarity with monohybrid crosses.
Common mistakes
Confusing genotype with phenotype.
Assuming that dominant traits are always more common in a population.
Forgetting that recessive traits are not lost but are masked.
Incorrectly predicting F2 generation ratios without understanding dominance.
Keywords
Mendel
Dominance
Recessive
Allele
Gene
Trait
Heredity
Genetics
Monohybrid Cross
F1 Generation
F2 Generation
Phenotype
Genotype
Practice preview
When a pure tall pea plant (TT) is crossed with a pure dwarf pea plant (tt), what is the phenotype of the F1 generation according to the Law of Dominance?…
easy
According to the Law of Dominance, in a heterozygous individual, which allele will express its trait?…
easy
Which of the following statements best describes the Law of Dominance?…
easy