Introduction
The law of dominance is a fundamental principle in genetics that explains how alleles interact in a heterozygous individual. This concept is crucial in understanding inheritance patterns and predicting the phenotypic outcomes of genetic crosses.
What is the Law of Dominance?
The law of dominance states that in a heterozygous individual (having two different alleles for a particular trait), one allele will be expressed over the other, masking its effects. The allele that is expressed is called the dominant allele, while the allele that is not expressed is called the recessive allele.
Examples
One classic example of the law of dominance is the inheritance of flower color in pea plants studied by Gregor Mendel. In this case, the allele for purple flowers (dominant) masks the allele for white flowers (recessive), resulting in all offspring having purple flowers.
- Example 1: Widow’s peak hairline (dominant) over straight hairline (recessive)
- Example 2: Attached earlobes (recessive) over free earlobes (dominant)
Case Studies
A study conducted on fruit flies (Drosophila melanogaster) showed how the law of dominance applies in determining eye color. The inheritance of red eyes (dominant) over white eyes (recessive) followed Mendel’s principles of dominance.
Statistics
According to genetic studies, approximately 75% of alleles in the human population exhibit dominant-recessive relationships. This statistic underscores the prevalence of the law of dominance in shaping genetic traits and variations.
Conclusion
The law of dominance is a cornerstone of genetics, providing insights into how alleles interact and influence phenotypic outcomes. Understanding this concept is essential for predicting inheritance patterns and studying genetic diversity.
