WHAT PROPORTION OF HER DAUGHTERS WILL BE CARRIERS FOR THE TRAIT IF THEIR FATHER IS NOT AFFECTED?

29 Jul WHAT PROPORTION OF HER DAUGHTERS WILL BE CARRIERS FOR THE TRAIT IF THEIR FATHER IS NOT AFFECTED?

Genetics (BI 211)

Spring 2013

Multiple choice (2 points each)

Spider size is regulated by 4 genes. If two 16 mg spiders mate, while many of
the progeny are 16 mg, the range in size goes from 4 mg to 28 mg. What increment in grams does each gene
contribute to spider size?
A. 3

B. 4

C. 6

D. 9

E. 12

2. In the ABO blood types, which
offspring is not possible?

A.
An individual with type O blood from a mother with type A and a father
with type AB.

B.
An individual with type AB blood from a mother with type B and a father
with type AB.

C.
An individual with type A blood from a mother with type O and a father
with type AB.

D.
An individual with type B blood from a mother with type A and a father
with type AB.

E.
all of the above

3. A female is heterozygous for the recessive
X-linked gene for Lesch-Nyhan syndrome.
What proportion of her daughters will be carriers for the trait if their father
is not affected?

A.
0%

B.
25%

C.
50%

D.
75%

E.
100%

4. What observation did Griffith make in his
experiments with Streptococcus pneumoniae?

A.
The mouse did not survive when injected with a mixture of live,
avirulent (smooth) Streptococcus
pneumoniae and heat-killed, virulent Streptococcus
pneumoniae.

B.
That DNA is the genetic material.

C.
The mouse survived injection of live virulent (smooth) Streptococcus pneumoniae.

D.
The heat-killed, virulent Streptococcus
pneumoniae was lethal to the mouse.

E.
All of the above

5. Which activity of E. coli DNA polymerase III is responsible for proofreading the
newly synthesized DNA?

A.
5′ to 3′ polymerase

B.
3′ to 5′ endonuclease

C.
3′ to 5′ exonuclease

D.
5′ to 3′ exonuclease

E.
none of the above

1. Why
is the upper limit of crossing over 50% recombinant gametes?

Two genes are linked on chromosome 2 of Drosophila melanogaster. After crossing a female parent that is
heterozygous at the two loci and a male parent that is homozygous recessive at
both loci the following data were obtained.
What type of specialized cross is being referred to above? Based on the data what is the arrangement of
the female heterozygote’s alleles and how many map units apart are they? Red
eyes is dominant to yellow. WT sex combs
is dominant to short.

Red eyes, short sex combs 250
flies

Yellow eyes, WT sex combs 250 flies

Yellow eyes, short sex combs 25 flies

Red eyes, WT sex combs 25 flies

2. A
Geneticist studying tail length in gerbils noticed that in the wild gerbil tails
varied in length in 4 centimeter intervals
from short to long with the longest being 28 centimeters. When he crossed a true breeding 12 centimeter
tailed gerbil to a true breeding 28 centimeter rose he obtained all 20
centimeter tailed gerbils. When he crossed
2 of the 16 centimeter progeny he obtained a range of sizes from 4-28
centimeters and the 4 centimeter tail occurred in 1/64 of the crosses progeny.

What is the
mode(s) of inheritance demonstrated by the above cross? How many genes are
involved? How many phenotypes are
possible for gerbil tail length from above?

What are possible
genotypes of the 12 centimeter gerbil crossed to the 28 centimeter gerbil. What was the genotype of the 20 centimeter
progeny?

3. A
scientist was studying anteaters and found an unusual population in the wild in
which a quarter of the animals had short snouts and 3/16 of the animals had
medium snouts. The rest had long
snouts. She then performed crosses
between these short-snouted animals and anteaters with normal (long)
snouts. What she saw in the offspring
was either what she expected, which was that all of the offspring had long
snouts (cross #1), or something weird, which was that only ¼ of the offspring
were normal, half had the abnormal, short snouts, and the last ¼ had medium
snouts.

What mode(s) of
inheritance is(are) illustrated by this example?

What are the
genotypes of the parents of cross 1 and cross 2?

Is it possible
to cross a true-breeding medium-snouted animal to a true-breeding

short snouted
animal and get a long snouted animal?
If not, explain – if so, show

genotypes.

4.
Two crosses were performed with eggplants to learn something about the
genetics of color (either purple or green) and shape (either plump or
lean).

Cross Offspring

purple, plump
female X green, lean male 36 purple, lean

40 green, plump

11
purple, plump

12
green, lean

green, lean
female X purple, plump male 49 purple, plump females

51
green, lean males

What are the
genotypes of the parents of the two crosses.
Be sure to be

THOROUGH in how
you assign genotypes. In other words,
provide all

information that
can be derived from these data including potential arrangement of the genes on
a chromosome.

5.
Draw a biochemical pathway (enzymes and substrates; use your
imagination) demonstrating how complementary gene interaction works. Also show it genetically by writing out the normal
ratio of genotypes, the altered ratio of genotypes, and the resultant phenotypes
based on yourbiochemical pathway.

6. A white elephant with black tusks was crossed
to a grey elephant with white tusks. The
F1 generation was all grey elephants with white tusks. The F2 generation had 100 progeny. 72 were grey and 28 were white. 56 had black tusks and rest had white
tusks. How many genes are segregating in
the original parental cross? What are
the genotypes of the parental, F1, and F2 individuals. What mode(s) of inheritance are demonstrated?

7.
What would be the effect on chromosome replication in E. coli strains
carrying the following mutations?

a.
dnaE (polymerase III subunit) ______________________________

b. polA (DNA polymerase I) _______________________________

c.
dnaG (primase) ____________________________________

d. lig (ligase)
________________________________________

e.
ssb (single stranded binding protein) ______________________________

f.
oriC (origin of replication) ____________________________________

g.
sigma 70 _________________________________________________

8.
Match the chromosomal mutation (1-5) or the disease (6-10) to the
correct terms. Multiple terms may be
needed for each number. Some terms may
not be used at all, others more than once.