Dominant and recessive genes are terms used to describe how certain traits are inherited based on the alleles (different forms of a gene) that an organism possesses.
Dominant Genes:
A dominant gene is one that can express its trait even when only one copy is present in an individual's genotype. This means that if an individual has at least one dominant allele, the characteristic associated with that allele will manifest in the phenotype (the observable traits).
Example of a Dominant Gene: The allele for brown eyes is often considered dominant over the allele for blue eyes. If an individual has at least one allele for brown eyes (BB or Bb), they will have brown eyes in their phenotype. Only individuals with two recessive alleles (bb) will have blue eyes.
Recessive Genes:
A recessive gene, in contrast, only expresses its trait when both copies of the gene (two recessive alleles) are present. If there is at least one dominant allele present, the recessive trait will not be expressed in the phenotype.
Example of a Recessive Gene: The allele for blue eyes (b) is a recessive trait. An individual must have two copies of the blue eye allele (bb) for their phenotype to display blue eyes. If they have one brown eye allele (B) and one blue eye allele (b) (genotype Bb), they will have brown eyes, as the brown eye allele is dominant.
Summary:
- Dominant Gene: Expresses the trait with one or more copies (e.g., brown eyes allele).
- Recessive Gene: Expresses the trait only when two copies are present (e.g., blue eyes allele).
This distinction helps to explain inheritance patterns in genetics, dictating how traits are passed from parents to offspring.
0 answers