Is a round yellow pea seed (genotype RrYy) an example of polygenic inheritance? Why or why not

Verified step by step guidance

1. Understand the concept of polygenic inheritance: Polygenic inheritance occurs when one characteristic is controlled by two or more genes, often resulting in a continuous range of possible phenotypes.
2. Identify the genes involved: In the case of the pea seed described, there are two genes mentioned, one determining the shape of the pea (R or r) and the other determining the color (Y or y).
3. Analyze the interaction of the genes: Each gene independently follows Mendel's laws of inheritance and contributes to a single trait (shape or color), rather than multiple genes contributing to a single trait as seen in polygenic inheritance.
4. Compare to monogenic inheritance: The traits mentioned (round vs. wrinkled, yellow vs. green) are each controlled by a single gene with two alleles, following Mendelian inheritance patterns, which is an example of monogenic inheritance.
5. Conclude the inheritance type: Since the traits are controlled by individual genes and not by the interaction of multiple genes affecting a single trait, the round yellow pea seed (genotype RrYy) is not an example of polygenic inheritance.

Key Concepts

Polygenic Inheritance

Polygenic inheritance refers to the genetic mechanism where multiple genes contribute to a single trait, resulting in a continuous range of phenotypes. Traits such as height, skin color, and seed color in plants often exhibit this pattern, as they are influenced by several alleles from different genes. In contrast to single-gene traits, polygenic traits do not follow simple Mendelian inheritance patterns.

Genotype and Phenotype

The genotype is the genetic makeup of an organism, represented by the alleles it possesses, while the phenotype is the observable expression of that genotype, influenced by both genetics and environmental factors. In the case of the round yellow pea seed with genotype RrYy, the phenotype would be round shape and yellow color, which are determined by the dominant alleles R (round) and Y (yellow).

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through the principles established by Gregor Mendel, focusing on single-gene traits that follow specific inheritance patterns. Mendel's laws, including the law of segregation and the law of independent assortment, explain how alleles segregate during gamete formation and how different traits are inherited independently. The round yellow pea seed example involves two traits, but each trait is determined by a single gene, making it a case of dihybrid inheritance rather than polygenic inheritance.