1. Expression in Phenotype:
- Dominant Allele: A dominant allele is expressed in the phenotype even if only one copy of it is present in the genotype (genetic makeup).
- Recessive Allele: A recessive allele is expressed in the phenotype only if two copies of it are present in the genotype (homozygous condition).
2. Effect on Traits:
- Dominant Allele: Dominant alleles mask or override the effects of recessive alleles when they are paired together in a heterozygous genotype.
- Recessive Allele: Recessive alleles are "hidden" or suppressed by dominant alleles in a heterozygous genotype.
3. Genotype Requirements:
- Dominant Allele: Dominant alleles can be either homozygous (two copies of the dominant allele) or heterozygous (one copy of the dominant allele and one copy of a recessive allele). In both cases, the dominant phenotype is expressed.
- Recessive Allele: Recessive alleles can only be expressed in a homozygous condition (two copies of the recessive allele).
4. Appearance in a Population:
- Dominant Allele: Dominant alleles are more likely to be visible in a population since they can be expressed in both homozygous and heterozygous individuals.
- Recessive Allele: Recessive alleles are less likely to be visible in a population because they require two copies to be expressed.
5. Inheritance Patterns:
- Dominant Allele: If a dominant allele is present in a parent's genotype, it has a 50% chance of being passed on to each offspring (assuming Mendelian inheritance).
- Recessive Allele: Recessive alleles are only inherited if both parents are carriers (heterozygous for the recessive allele) or if both parents are homozygous recessive.
Understanding dominant and recessive alleles is essential in genetics and helps explain the inheritance patterns and variation of traits within a population.
