Consider two gene loci in the mouse, locus 1 and locus 2. Each locus is on a different, nonhomologous
autosomal chromosome . Alleles at locus
1 influence fur color. Allele A is for black and allele a is for white. Allele A
is completely dominant to allele a . Alleles at locus 2 influence stature; allele
B is for tall and allele b is for short. Allele B
is completely dominant to allele b.
Mouse 1, genotype Aa Bb, mates with female
mice , genotype Aa Bb; 100 progeny are produced.
What fraction of the gametes from mouse 1 is expected to be genotype ab ?
______: What fraction of the progeny is expected to
be true-breeding for both tall stature and fur color?
______: How many progeny are expected to be short
with white fur? Show your calculations.
___: How many progeny are expected to
be homozygous at both loci? Show your
If you randomly choose two progeny mice, one at a time, what is the probability
that both mice are tall and black? Show your calculations.
Using the gene loci, alleles and phenotypes
as described in question 2, consider this mating between Mouse 3, black and
tall, and mouse 4, black and tall. That
mating produced these progeny: 55 black and short, 165 black and tall, 20 white
and short, 62 white and tall.
what is the expected number of progeny of the phenotypic class, white and tall? Show
What is the Chi-square value for these observed and expected data? Show your work. When calculating
the Chi-square value, please do not
use fractions (round up, or down as appropriate).
___: How many degrees of freedom are
used for the Chi-square test in this situation?
_______________________: What is the
approximate Chi-square probability for this Chi-square value and degrees of
____: Mouse 3 mated with mice that had
the phenotype short & white, and produced 100 progeny. How many progeny are expected to have the
phenotype, black and tall?
_____________: In addition to the gene loci, alleles and phenotypes
described in question 1, consider a third gene locus with alleles D and d; D
for long fur, and d for short fur. D is
completely dominant to allele d. This
gene locus segregates independently of the other two loci. Mouse 5, genotype Aa Bb Dd, mates with mouse 6 of the same genotype and they have 200
progeny. How many of the progeny are
expected to have the phenotype, black fur, tall
& long fur?
pts). State the null hypothesis that should be considered with the
Chi-Square test in question 4