In a certain species of flowering plants with a diploid genome, four enzymes are
ID: 65633 • Letter: I
Question
In a certain species of flowering plants with a diploid genome, four enzymes are involved in the generation of flower color. The genes encoding these four enzymes are on different chromosomes. The biochemical pathway involved is as follows: the figure shows that either of two different enzymes is sufficient to convert a blue pigment into a purple pigment. A true-breeding green-flowered plant is mated with a true-breeding blue-flowered plant. All of the plants in the resultant F| generation have purple flowers. F_1 plants are allowed to self-fertilize, yielding an F_2 generation. Show genotypes for P. F_1 and F_2 plants, and indicate which genes specify which biochemical ,steps. Determine the fraction of F_2 plants with the following phenotypes: white flowers, green flowers, blue flowers, and purple flowers. Assume the green-flowered parent is mutant in only a single step of the Hr pathway.Explanation / Answer
According to the given information, the gene that code for a specific enzyme that codes a specific color is diploid in nature.
In the given information, it is mentioned that either of two different enzymes (alleles) that code for white, green, blue colored flower plant convert into a purple pigment. This indicates that the white, green, blue colored flower plants can be expressed in homozygous condition while in heterozygous state they code purple colored flower plant. Thu, this condition describes codominance. But if assume the green-flowered plant is mutant than the condition describes incomplete dominance, where blue colored flower plant is unable to express completely and forming intermediate color that is purple colored flower plant.
The cross will be as follows:
The genotype of the parents, F1, and F2 generation are shown in the cross. The phenotypic ratio of F2 generation is 1:2:1, where 1 blue, 1 green, and 2 purple flowered plants are produced.