1. Black pansies were recently bred
for the first time by crossing homozygous strains of blue and
magenta and intercrossing the purple F1's. In addition to the few
black pansies, the F2's contained lots of purple, some blue, and
some magenta offspring. What is the genotype of a black
pansy?
2. Rabbits can have several variations in
coat color as a result of a series of alleles: full-color (C) is
dominant over all other alleles, chinchilla (cch) is
dominant over Himalayan (ch) and albino (c), and
Himalayan is dominant over albino. A full-color rabbit and a
Himalayan rabbit were crossed. The progeny consisted of half
full-color and half chinchilla. What was the genotype of the
full-color parent?
3. A man with a rare hereditary condition
known as hypophosphatemia marries a normal woman. They have 4
daughters, all of whom have hypophosphatemia, and 3 sons, all of
whom are normal. What is the genotype of the father? Assuming
they marry outside of their family, what is the probability that
the daughters will have daughters with
hypophosphatemia?
4. A true-breeding, white-eyed,
normal-winged female fruit fly is crossed with a true-breeding,
red-eyed, curly-winged male. The F1 female flies are all red-eyed
and curly-winged. The F1 male flies are all white-eyed and
curly-winged. What are the genotypes of the parental flies, the
F1 males and females, and what would be the expected phenotype(s)
of the F2 flies if the F1 males and females were
intercrossed?
5. What is the protein sequence
translated from the following complete template DNA
strand?
A A T A C G C A T T G A C C T C A A
C T G
What would be the effect on the protein
of a mutation changing the 13th base (first C of a pair) to a
T?
6. Tribbles come in pink, light blue,
purple, and white. These colors are controlled by two genes in
two separate pathways: R- results in red pigment, and rr results
in white; B- results in blue pigment, and bb results in white.
When a homozygous light blue and a homozygous pink were left
together for a few days, only purple tribbles were produced. By
the time these purple progeny were discovered, they had
intercrossed, and produced all four colors in the F2, with purple
the most common and white the rarest.
a. What were the genotypes of the
original light blue and pink tribbles?
light blue:
pink:
b. What was the genotype of the F1
purple tribbles?
c. What proportion of light blue
tribbles would be expected among the F2 progeny?
d. What would be the genotype of a pink
tribble in the progeny of a TESTCROSS of the purple F1's?
e. What proportion of pink tribbles
would be expected in this testcross?
7. The following metabolic pathway
shows color phenotypes associated with three compounds. Gene A codes
for enzyme 1, which catalyzes the reaction that changes compound X
into compound Y; Gene B codes for enzyme 2, which catalyzes the
reaction that changes compound Y into compound Z. Both genes have
dominant alleles (A, B) that produce functional enzymes and
recessive alleles (a, b) that produce non-functional enzymes.
a. What would be the phenotypes
of the following genotypes?
b. What phenotypic ratio would be
expected in an intercross of two
dihybrids?