Connect 1-semester Access Card For Genetics
Connect 1-semester Access Card For Genetics
5th Edition
ISBN: 9780077515041
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr., Charles (chip) Aquadro
Publisher: McGraw-Hill Education
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Chapter 4, Problem 32P

In 1919, Calvin Bridges began studying an X-linked recessive mutation causing eosin-colored eyes in Drosophila. Within an otherwise true-breeding culture of eosin-eyed flies, he noticed rare variants that had much lighter cream-colored eyes. By intercrossing these variants, he was able to make a true-breeding cream-eyed stock. Bridges now crossed males from this cream-eyed stock with true-breeding wild-type females. All the F progeny had red (wild-type) eyes. When F flies were intercrossed, the F progeny were 104 females with red eyes, 52 males with red eyes, 44 males with eosin eyes, and 14 males with cream eyes. Assume that these numbers represent an 8:4:3:1 ratio.

  1. Formulate a hypothesis to a. explain the F1 and F2 results, assigning phenotypes to all possible genotypes?

  2. What do you predict in the F1 and F2 generations if the parental cross is between true-breeding eosin eyed males
    and true-breeding cream eyed females?

  3. What do you predict in the F1 and F2 generations if the parental cross is between true-breeding eosin eyed females
    and true-breeding cream eyed males?

Expert Solution
Check Mark
Summary Introduction

a.

To determine:

The hypothesis derived from the results obtained from crossing true breeding cream-colored male and true-breeding wild female.

Introduction:

Fertilization is the process by which the male gamete, sperm, fertilize with the female gamete, ovary. The process brings about the fusion of two haploid pronuclei into a diploid zygote.

Explanation of Solution

The hypothesis that can be derived from the results is that mutation in the wild type allele results in the production of eosin eyed progeny. The presence of criss-cross inheritance in the wild and the mutated variant results in the production of cream eyed progeny. This hypothesis supports the presence of criss-cross inheritance.

Expert Solution
Check Mark
Summary Introduction

b.

To determine:

The predicted progeny in F1 and F2 generation if the cross is made between true-breeding eosin eyed males and true-breeding cream-colored females.

Introduction:

The dominant allele masks the expression of the recessive allele. Therefore, the dominant allele is expressed in homozygous and heterozygous genotype while the recessive phenotype is only expressed under homozygous condition.

Explanation of Solution

The progeny from the cross between true-breeding eosin eyed males, and true-breeding cream-colored females are as follows:

Gametes Xe Y
Xc Xe Xc
Xc Y
Xc Xe Xc
Xc Y

The F2 progeny is derived as follows:

Gametes Xc Y
Xe Xe Xc
Xe Y
Xc Xc Xc
Xc Y

The progeny obtained will be cream eyed males (Xc Y), eosin eyed males (Xe Y), cream-colored females (Xc Xc) and variant cream colored female (Xe Xc).

Expert Solution
Check Mark
Summary Introduction

b.

To determine:

The predicted progeny in F1 and F2 generation if the cross is made between true-breeding eosin eyed females and true-breeding cream colored males.

Introduction:

The Punnett square is used to depict the genetic cross between two parents and all the possibilities of the resulting progeny that can help in identifying the genotype and phenotype of the hybrids produced.

Explanation of Solution

The progeny from the cross between true-breeding eosin eyed females, and true-breeding cream colored males are as follows:

Gametes Xc Y
Xe Xc Xe
Xe Y
Xe Xc Xe
Xe Y

The F2 progeny will be derived as follows:

Gametes Xe Y
Xe Xe Xe
Xe Y
Xc Xe Xc
Xc Y

The progeny obtained will have male genotype Xc Y, and Xe Y and females will have genotype Xe Xe and Xe Xc

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Chapter 4 Solutions

Connect 1-semester Access Card For Genetics

Ch. 4 - One oak tree cell with 14 chromosomes undergoes...Ch. 4 - Which types of cell division mitosis, meiosis I,...Ch. 4 - Complete the following statements using as many of...Ch. 4 - The five cells shown in figure a e on the next...Ch. 4 - One of the first microscopic observations of...Ch. 4 - A person is simultaneously heterozygous for two...Ch. 4 - Assuming i that the two chromosomes in homologous...Ch. 4 - In the moss Polytrichum commune, the haploid...Ch. 4 - Does any reason exist that would prevent meiosis...Ch. 4 - Sister chromatids are held together through...Ch. 4 - The pseudoautosomal regions PARs of the X and Y...Ch. 4 - Somatic cells of chimpanzees contain 48...Ch. 4 - In humans: a. How many sperm develop from 100...Ch. 4 - Women sometimes develop benign tumors called...Ch. 4 - In a certain strain of turkeys, unfertilized eggs...Ch. 4 - Imagine you have two pure-breeding lines of...Ch. 4 - A system of sex determination known as...Ch. 4 - In Drosophila, the autosomal recessive brown eye...Ch. 4 - Barred feather pattern is a Z-linked dominant...Ch. 4 - When Calvin Bridges observed a large number of...Ch. 4 - In a vial of Drosophila, a research student...Ch. 4 - In 1919, Calvin Bridges began studying an X-linked...Ch. 4 - In Drosophila, a cross was made between a...Ch. 4 - As we learned in this chapter, the white mutation...Ch. 4 - The following is a pedigree of a family in which a...Ch. 4 - Each of the four pedigrees that follow represents...Ch. 4 - The pedigree that follows indicates the occurrence...Ch. 4 - Duchenne muscular dystrophy DMD is caused by a...Ch. 4 - The X-linked gene responsible for DMD encodes a...Ch. 4 - Males have hemophilia when they are hemizygous for...Ch. 4 - Consider the following pedigrees from human...Ch. 4 - Several different antigens can be detected in...Ch. 4 - The ancestry of a white female tiger bred in a...Ch. 4 - The pedigree at the bottom of the page shows the...Ch. 4 - In 1995, doctors reported a Chinese family in...Ch. 4 - In cats, the dominant 0 allele of the X-linked...Ch. 4 - In marsupials like the opposum or kangaroo, X...Ch. 4 - The pedigree diagram below shows a family in which...
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