Download Predicted vs. Observed Results

Predicted vs. Observed Results
Problem: How do the predicted results
compare to the actual results in a genetic
cross as the sample size increases?
Background:
– Black is dominant fur color in mice, white is
recessive.
– What is the chance for getting a B or a b in a
heterozygous mouse?
Hypothesis:
Procedure:
1. Make a cross of Bb x Bb using a punnett square
to find the expected results of crossing 2
heterozygous mice.
2. Mark 2 coins—B on one side and b on the other.
Each coin represents one of the heterozygous
mice.
3. Flip the coins together 40 times, and record the
results of the offspring in table 1 .
4. Calculate the percentage of the resulting
phenotypes in table 1.
5. Repeat steps 1-4 except cross Bb x bb, changing
one of the coins to b on one side and b on the
other and use table 2 to record data.
Data:
Table 1 BbxBb
Gene
combinations
BB
Bb
bb
Total expected in
40 tosses
Total observed in
40 tosses
Phenotype
Total expected
Total observed
Black
White
Table 2 Bbxbb
Gene
combinations
BB
Bb
bb
Total expected in
40 tosses
Total observed in
40 tosses
Phenotype total #
Black
White
• spreadsheet
Data Analysis:
1. If I have a black mouse and I want to find out what
its genotype is, how could I set up an experiment to
determine the genotype of the mouse?
2. How did your expected results compare to your
observed results?
3. How did the class expected results compare to the
class observed results?
4. Explain what each side of the penny represented,
what the flipping of the penny represented, how it
relates to the chromosomes, and what the sides
that were facing up represented.
Conclusion: Write a CER paragraph to explain
how the predicted results compare to the
expected results as the sample size increases.