# Genetics Mouse question

*label*Biology

*timer*Asked: Oct 22nd, 2015

**Question description**

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
calculations**.

____:
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
your work__

________:
What is the Chi-square value for these observed and expected data? ** Show your work**. When calculating
the Chi-square value,

**(round up, or down as appropriate).**

__please do not use fractions_____: 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 freedom?

____: 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?

**5. (3
pts). **State the null hypothesis that should be considered with the
Chi-Square test in question 4