Final answer:
The allele for green eyes is represented by the lowercase 'g', which is the recessive allele for eye color in humans when compared to the uppercase 'B' representing the dominant brown eyes allele.
Step-by-step explanation:
In the context of Mendelian genetics, the notation of alleles plays a crucial role in representing the inheritance patterns of traits. The use of uppercase and lowercase letters adheres to a convention where dominant alleles are denoted by uppercase letters, while recessive alleles are represented by lowercase letters. In the scenario of eye color, the allele for brown eyes is designated as 'B,' and for green eyes, it is 'g.'
Genotypes, representing an individual's genetic makeup, are composed of two alleles—one from each parent. Homozygous dominant individuals, possessing two dominant alleles, are denoted by an uppercase letter repetition (e.g., BB for brown eyes). On the other hand, heterozygous individuals, carrying one dominant and one recessive allele, are represented with a combination of uppercase and lowercase letters (e.g., Bg for one brown and one green eye allele).
Given that brown eye color is typically considered dominant over green in the inheritance of human eye color, an individual with the genotype Bg would exhibit the dominant brown eye trait. This is because the presence of even one dominant allele (B) is sufficient to express the dominant phenotype, overshadowing the recessive green allele (g). Consequently, despite carrying the genetic information for green eyes, the person with a Bg genotype would phenotypically manifest brown eyes, illustrating the principle of dominance in Mendelian genetics.
Understanding the symbolism of uppercase and lowercase letters in genetic notation provides a concise and standardized way to convey information about the inheritance of traits, facilitating the interpretation of genotypes and their corresponding phenotypes in the context of Mendelian inheritance.