How do Mendel’s experiments show that the Traits may be dominant or recessive?
Hint: Mendel’s experiments demonstrate that traits can be classified as dominant or recessive through a genetic cross between two individuals with homozygous genotypes, which possess either entirely dominant or entirely recessive alleles, leading to contrasting phenotypes for certain genetic characteristics.
Complete answer:
Mendel’s experiments reveal that traits may be dominant or recessive by conducting a monohybrid cross. When two pure breeding varieties undergo a monohybrid cross, the resulting hybrid offspring consistently exhibit one parental trait, while the opposing trait remains unexpressed in the F1 generation. This observation implies that alleles of a gene are typically classified as either dominant or recessive, with the dominant allele in the F1 hybrids concealing the expression of the recessive allele.
Additional Information: Alleles are generally categorized as either dominant or recessive. Dominant alleles manifest their effects even when the individual possesses only one copy of the allele (often described as heterozygous). For instance, the allele for yellow seeds is dominant, meaning that only one copy of the ‘yellow seed’ allele is needed to produce yellow seeds (though having two copies will still result in yellow seeds). When individuals possess two copies of an allele, only the effects of recessive alleles become evident. For example, the allele for green seeds is recessive, so to have green seeds, an individual must have two copies of the ‘green seed’ allele.
Note: When both alleles are dominant, this phenomenon is referred to as codominance. The resulting trait occurs due to the equal expression of both alleles. A prime example of this is blood type AB, which results from the codominance of the A and B dominant alleles.