Genetics (BI 211) Name: Write on back of last page (1 point)
Multiple choice (2
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?
2. In the ABO blood types, which offspring is not
An individual with type O blood from a mother with type A and a father
with type AB.
An individual with type AB blood from a mother with type B and a father
with type AB.
An individual with type A blood from a mother with type O and a father
with type AB.
An individual with type B blood from a mother with type A and a father
with type AB.
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?
4. What observation did Griffith make in his
experiments with Streptococcus pneumoniae?
The mouse did not survive when injected with a mixture of live,
avirulent (smooth) Streptococcus
pneumoniae and heat-killed, virulent Streptococcus
That DNA is the genetic material.
The mouse survived injection of live virulent (smooth) Streptococcus pneumoniae.
The heat-killed, virulent Streptococcus
pneumoniae was lethal to the mouse.
All of the above
5. Which activity of E. coli DNA polymerase III is responsible for proofreading the
newly synthesized DNA?
5′ to 3′ polymerase
3′ to 5′ endonuclease
3′ to 5′ exonuclease
5′ to 3′ exonuclease
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
Yellow eyes, WT sex combs 250
Yellow eyes, short sex combs 25
Red eyes, WT sex combs 25
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
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
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).
purple, plump female X green, lean
male 36 purple, lean
40 green, plump
green, lean female X purple, plump
male 49 purple, plump females
green, lean males
What are the genotypes of the
parents of the two crosses. Be sure to
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.
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
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
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.
1. A B C F E_o_D G H a.
A D o E F B C G H c. Chromosome 21
A B C D o E F E F G H e. Insertion
f. Chromosome 13
A B C D o E F F E G H g. Non-reciprocal
h. Pericentric inversion
5. A B D o E F G H i. aneuploidy
6. Downs Syndrome k.
l. Chromosome 5
Edwards Syndrome m.
Turner Syndrome o. Deletion
p. Paracentric inversion
Kleinfelter Syndrome q.
Cri du Chat s. Translocation
9. In human males a
small portion of the Y chromosome is called SRY. Characterize the function of SRY as
specifically as you can. A non
reciprocal translocation of SRY to Chromosome 10 has occurred prior to meiosis,
in a male patient accidentally exposed to high doses of radiation at a power
plant. Explain briefly how the radiation
might have caused the translocation.
What percentage of male progeny will potentially be overly aggressive
and may end up in prison if this man marries a completely normal woman and has
10. Sometimes during abnormal transcription
events small RNA/DNA hybrids are left in the E. coli genome after transcription
is over. Normally they are removed by an
enzyme called RNAseH. E. colideleted for OriC are inviable
unless RNAseH is also deleted at the same time. These cells grow slowly and are “sick” but
still survive. Explain why cells without
OriC are inviable and why the cells containing the double deletion of OriC and
RNAseH remain viable.
11. In Eukaryotic
systems DNA origins of replication are only activated once per cell cycle. However viruses often need to make multiple
copies of their genome in one cell cycle, for instance the SV40 animal virus
generates 100,000 copies in a single cell cycle. In part, to do this it uses a protein denoted
T-antigen. When T-antigen is incubated in vitro with circular viral DNA
carrying the SV40 origin of replication, topoisomerase I, and ATP the following
structure is observed:
Singled stranded DNA
Double stranded viral
What activity in addition to binding the origin of
replication must T-antigen also possess in order to create the above
structure? How does this differ from
what occurs at the E. coli origin of replication?