Mendelian Analysis

1
Mendelian Analysis
2
What is the probability that the first child of
this couple is affected by Tay Sachs disease, a
recessive disorder?

• Answers
• 1/9
• 4/9
• 2/3
• 1/4

a. Is correct, 2/3 x 2/3 x 1/4
3
A1x pigment a 0white
Incomplete Dominance
AA purple
aawhite
Aapink
4
Co-Dominance
5
Marigolds come in yellow and orange colors. Two
true breeding yellow varieties were obtained from
different seed companies and crossed with the
following outcome Yellow var 1 x yellow var 2
gt F1 orange F2 9/16 orange 7/16 yellow What
are the genotypes of var 1, var 2

• Answers
• Aabb, aaBb
• AaBb, AaBb
• AABb, aabb
• aaBB, AAbb

d. Is correct
6
c. Is correct
7
You found 2 mutants with the same phenotype in
flies (white eye). To tell whether the mutations
are in the same gene you perform an allelism test
with the following outcome White eye mutant 1 x
white eye mutant 2 F1 is red eye (wild type)

• Answers
• Mutant 1 and 2 complement
• Mutations 1 and 2 are in the same gene
• Mutant 1 and 2 are allelic

a. Is correct, since the mutants complement, they
are not allelic
8
X2 Table
reject
accept
9
In tomatoes the mutants green stem (g) and potato
leaf shape (p) are both recessive and assort
independently. F1 progeny is obtained by
crossing ggpp x GGPP F1 GgPp (purple stem,
tomato leaf) F2 344 purple stems, tomato leaf
134 purple stem, potato leaf 128 green stem,
tomato leaf 34 green stem, potato leaf . We
test for independent assortment with X2.How do
you calculate the expected value for the first
phenotype? (Total progeny size640)

• Answers
• (3/4) x 640
• (1/4) x 344
• (9/16) x 640
• 9/16 x 344

c. Is correct
10
We found a X2 value of 3.8, with 3 df
corresponding to P30

• Therefore
• We accept the null hypothesis (independent
  assortment)
• We reject the null hypothesis
• Data insufficient to draw a conclusion

a. Is correct