What is the genotype and phenotype of the parents? - ProProfs Discuss
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What is the genotype and phenotype of the parents?

In mice, there exists a gene for ear shape with two alleles: normal (T) and twisted (t). A cross has been made between two groups of mice. Both groups have the same genotype. The F1 progeny are 735 mice with normal ears and 265 mice with twisted ears.

This question is part of natural sciences 5

Asked by Tyler, Last updated: Nov 16, 2020

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John Smith

John Smith

John Smith
John Smith

Answered Sep 08, 2016

Tt and normal -choices a and e can be ruled out at once, since they offer the dominant homozygous choice e or heterozygous genotype paired with a recessive phenotypethis is clearly impossible. choice c may also be eliminated, as all offspring from a tt x tt cross would be phenotypically recessive. the phenotypic ratio for the f1 is 735:265 for normal:twisted ears, or about 3:1. a 3:1 phenotypic ratio is associated with a 1:2:1 genotypic ratio, and both ratios will result from a crossing of heterozygotes parents, in this case, tt x tt. a punnett square solution will verify this conclusion.
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