Question

In Drosophila, gray body color is dominant to ebony body color, while long wings are dominant to vestigial wings. Assuming that the P₁ individuals are homozygous, work the following crosses through the F₂ generation, and determine the genotypic and phenotypic ratios for each generation.
gray, vestigial x ebony, long

Accepted Answer

Identify the traits and their dominance relationships: gray body color (G) is dominant to ebony (g), and long wings (L) are dominant to vestigial wings (l). Since the P₁ individuals are homozygous, assign genotypes accordingly. For example, gray body with long wings would be GGLL, and ebony body with vestigial wings would be ggll. Set up the P₁ cross using the homozygous parents: cross GGLL (gray, long) with ggll (ebony, vestigial). This will produce the F₁ generation, which will be heterozygous for both traits (GgLl). Determine the phenotype and genotype of the F₁ generation: since both traits are dominant, all F₁ individuals will show gray body and long wings, and their genotype will be GgLl. Set up the F₁ cross to produce the F₂ generation: cross two F₁ individuals (GgLl x GgLl). Use a dihybrid Punnett square to determine the possible genotypes and phenotypes of the F₂ offspring. Calculate the genotypic and phenotypic ratios for the F₂ generation by analyzing the Punnett square results. The phenotypic ratio for two independently assorting dominant traits typically follows a 9:3:3:1 pattern (9 gray long, 3 gray vestigial, 3 ebony long, 1 ebony vestigial), and the genotypic ratio can be derived by counting all genotype combinations.

비슷한 문제에 대한 검증된 영상 답변:

주요 개념

Mendelian Inheritance and Dominance

Genotypic and Phenotypic Ratios

Dihybrid Cross and Independent Assortment