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Zoo/Bot 3333
Genetics
Quiz 4
November 20, 2006
For answers to the quiz click here:
1. Arabidopsis thaliana has among the smallest genomes in higher plants, with a haploid genome size of
about 100 Mbp. Assuming B form DNA, in a single somatic cell, if the DNA from all of the chromosomes
was laid end-to-end, it would stretch: a) 0.3 mm; b) 6.8 cm; c) 3 meters; d) 6 kilometers; e) from New York
City to Hartford, Connecticut.
2. A kan r tet r plasmid is treated with the restriction enzyme BglI, which cleaves inside the tetracycline (tet)
gene. The DNA is annealed with and ligated to a BglI digest of Neurospora DNA and then used to
transform E. coli. Which phenotype is expected to contain Neurospora DNA inserts?
a) kan r tet r; b) kan s tet s; c) kan r tet s; d) kan s tet r; e) tet s either kan sor kan r.
3. The accompanying table shows the presence or absence of seven sequence-tagged sites (STS’s)
numbered 1-7, in each of six BAC clones, designated A-F. A “+” in the table means that PCR primers
specific to the STS are able to amplify the sequence from the clone, a “-“ means that the sequence can not
be amplified from the clone.
BAC Clone
A
B
C
D
E
F
1
+
+
-
2
+
+
3
+
-
STS marker
4
5
+
+
+
+
6
+
+
-
7
+
-
The relative order of the STS sites within the cloned genome can be ordered as:
a) 3427165; b) 1527634; c) 3514276; d) 7251643; e) 2541673
Gene Q
Gene R
Gene S
Gene T
Questions 4-5 pertain to the following
ASO
Q1
Q2
R1
R2
S1
S2
T1 T2
experiment. Four pairs of PCR primers




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
Somatic Cell
were used to amplify DNA isolated from
Sperm number
one man's somatic cells, and from 20

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
1
single sperm that he donated for this
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2
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3
study. Each primer pair amplifies a
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4
different region of the human genome,
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5
referred to as genes Q, R, S and T. Each
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6
of these amplified regions was then
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


7
divided into 8 aliquots (i.e. 8 identical
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8
subsamples) and these 8 DNA samples
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
9
were denatured and spotted onto
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10
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11
membrane strips for nucleic acid
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12
hybridization analysis, as shown in the
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13
figure at the right. The membranes were
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14
hybridized to 8 different oligonucleotide


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15
probes, which are designed to distinguish
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16
single-nucleotide base differences in the
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17
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18
DNA. The paired oligonucleotides
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19
Q1/Q2, R1/R2, S1/S2 and T1/T2 are




20
therefore regarded as allele-specific
oligonucleotide probes (ASOs). A black circle on the diagram indicates that the amplified DNA
hybridized to the indicated ASO probe (e.g. binding of the radiolabeled oligonucleotide to the amplified
DNA, as detected by autoradiography).
4. Based on the results shown, which gene(s) could be X-linked?
a) Q; b) R; c) S; d) T; e) more than one of the above.
5. Which gene(s) must be autosomal and homozygous for a particular ASO? a) Q; b) R; c) S; d) T; e) more
than one of the above.
Regan's DNA
Butch
Coolridge’s
DNA
Tony
Contralto' s
DNA
victim's DNA
6. On the basis of the above data, what is the map distance between the two genes that are linked to one
another? a) 5 map units; b) 10 map units; c) 15 map units; d) 20 map units; e) 25 map units.
Glass #2
Glass #1
cigarette
victim's
fingernails
Questions 7-8 pertain to the
following: Lt. Sandy Hippowits
of the 32rd precinct has a
crime to solve. The female
victim, stabbed with a kitchen
knife, lies on the sofa in an
apartment, which she shares
with her sister, Regan. There
are two empty glasses on the
coffee table, a half-eaten
birthday cake, and a cigarette
in the ashtray. Both of the
glasses have lipstick on them,
but not the cigarette. The
victim's purse also lies open on the coffee table; it contains her keys and lipstick, but no wallet or credit
cards. It also contains a matchbook for the Dadading Club with a phone number written on the interior of
the matchbook. The phone number leads to Tony Contralto, owner of the Dadading club. A credit card
belonging to the deceased turns up in the hands of Butch Coolridge, an itinerant ex-boxer who says he got
it out of the Dumpster at the Dadading club. The victim’s wallet was in the dumpster, wiped clean of
prints. Interviews with neighbors indicate that a major quarrel was heard the night of the murder, with
someone heard screaming "it’s my party and I'll cry if I want to". All suspects deny being present at the
time of the murder. Forensic analysis of the crime scene indicated that the victims' fingerprints were on
one of the glasses, while her sister Regan's fingerprints were on the other glass. The lipstick on the
victim's glass appeared to come from the lipstick in the purse. DNA from cells located on both glasses and
the cigarette could also be recovered. In addition, there was skin under the fingernails of the victim, which
could also be typed using minisatellite markers. These samples were compared with the DNA of the
principal suspects with the results shown.
7. Which of the following is the likely murderer? a) Regan, b) Tony Contralto; c) Butch Coolridge; d)
evidence implicates them all; e) evidence suggests another potential suspect.
8. Whose birthday was it? a) the victim’s; b) Tony Contralto; c) Butch Coolridge; d) Regan; e) two of the
above are correct.
Questions 9 and 10 pertain to the following. Six independently derived mutants are recovered in Neurospora
that are all able to grow on compound Z. The mutants are then grown on minimal media supplemented with
one of 6 chemicals all known to be precursors to compound Z. A summary of the ability of the mutants to
grow on media containing these chemicals is indicated below, where a “+” sign indicates growth and a “-”
sign indicates no growth.
Mutant
number
1
2
3
4
5
6
A
B
Chemical Compounds
C
D
E
F
Z

+


+
+

+
+
+
+
+

+

+
+
+







+


+

+
+
+
+
+
+




+

9. The immediate precursor to compound Z (i.e. next to last compound in pathway) is:
a) E; b) C; c) F; d) A; e) none of the above.
10. A mutation in gene 2 should lead to an accumulation in which metabolite in the pathway?
a) E; b) C; c) D; d) A; e) none of the above.