The synthesis of flower pigments is known to be dependent on enzymatically controlled biosynthetic pathways. For the crosses shown here, postulate the role of mutant genes and their products in producing the observed phenotypes: P₁: white strain A×white strain B F₁: all purple F₂: 9/16 purple: 7/16 white

Key Concepts

Biosynthetic Pathways

Biosynthetic pathways are series of enzymatic reactions that lead to the production of complex molecules from simpler ones. In the context of flower pigments, these pathways involve specific enzymes that catalyze the conversion of precursor compounds into pigments, such as anthocyanins, which give flowers their color. Understanding these pathways is crucial for analyzing how mutations in genes can affect pigment production and, consequently, flower color.

Genetic Mutations

Genetic mutations are changes in the DNA sequence of a gene that can alter the function of the gene's product, typically a protein. In this scenario, mutant genes may lead to the absence or malfunction of enzymes in the biosynthetic pathway, resulting in the observed phenotypes of flower color. Identifying whether these mutations are dominant or recessive is essential for predicting the inheritance patterns seen in the F1 and F2 generations.

Phenotypic Ratios

Phenotypic ratios describe the relative frequencies of different observable traits in the offspring of a genetic cross. The 9:7 ratio observed in the F2 generation suggests a modified Mendelian inheritance pattern, likely due to epistasis, where one gene's expression masks or modifies the effect of another gene. Analyzing these ratios helps in understanding the genetic interactions and the roles of the mutant genes in determining flower color.