Three pairs of genes with two alleles each (A₁ and A₂, B₁ and B₂, and C₁ and C₂) control the height of a plant. The alleles of these genes have an additive relationship: Each copy of alleles A₁, B₁, and C₁ contributes 6 cm to plant height, and each copy of alleles A₂, B₂, and C₂ contributes 3 cm. Identify all possible genotypes for plants with an expected height of 33 cm.

Key Concepts

Additive Gene Interaction

Additive gene interaction occurs when multiple genes contribute to a single trait, with each allele having a specific effect on the phenotype. In this case, the alleles A₁, B₁, and C₁ each add 6 cm to the plant's height, while A₂, B₂, and C₂ add 3 cm. Understanding this concept is crucial for calculating the total height based on different combinations of alleles.

Genotype and Phenotype Relationship

The genotype refers to the genetic makeup of an organism, while the phenotype is the observable trait resulting from the genotype. In this scenario, the expected height of 33 cm is the phenotype that results from specific combinations of the alleles A₁, A₂, B₁, B₂, C₁, and C₂. Analyzing how different genotypes lead to this phenotype is essential for solving the problem.

Combinatorial Genetics

Combinatorial genetics involves determining all possible combinations of alleles that can produce a specific phenotype. Given the additive contributions of the alleles in this question, one must calculate the various combinations of A, B, and C alleles that sum to the target height of 33 cm. This concept is key to identifying all possible genotypes that meet the height requirement.