Zoo/Bot 3333
Genetics
Quiz 4
November 24, 2008
For the answers to the quiz, please click here:
Gene Q
Gene R
Gene S
Gene T
Questions 1-4 pertain to the
ASO
Q1
Q2
R1
R2
S1
S2
T1 T2
following experiment. Four pairs of
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Somatic Cell
PCR primers were used to amplify
Sperm number
DNA isolated from one man's
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1
somatic cells, and from 20 single
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2
sperm that he donated for this study.
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3
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4
Each primer pair amplifies a
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different region of the human
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genome, referred to as genes Q, R, S
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and T. Each of these amplified
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regions was then divided into 8
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9
aliquots (i.e. 8 identical subsamples)
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and these 8 DNA samples were
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denatured and spotted onto
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membrane strips for nucleic acid
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hybridization analysis, as shown in
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the figure at the right. The
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membranes were hybridized to 8
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different oligonucleotide probes,
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which are designed to distinguish
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single-nucleotide base differences in
the DNA. The paired oligonucleotides Q1/Q2, R1/R2, S1/S2 and T1/T2 are therefore regarded as allelespecific 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).
1. 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.
2. Based on the results shown, which gene(s) could be on the Y chromosome?
a) Q; b) R; c) S; d) T; e) more than one of the above.
3. 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.
4. 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.
Consider the gel at the right, derived from a sequencing reaction based on the Sanger chain termination
method.
5. The sequence of the TEMPLATE STRAND would be:
A
G
C
T
a) 5'-ACGTGCACGTGC-3';
b) 5'-GCACGTGCACGT-3';
c) 5'-TGCACGTGCACG-3';
d) 5'-GCTAGCGCTAGC-3';
e) 5'-CGTGCACGTGCA-3'.
6. True or false. Of the four DNA polymerase reactions used for
Sanger DNA sequencing, only one contains deoxyadenosine
triphosphate.
Questions 7-8 pertain to the flowgram data on the left, obtained from a DNA
sequencing run using the massively parallel pyrosequencing technology.
7. True or false. Using the pyrosequencing technology, a base read occurs when a
fluorescent molecule is incorporated into the DNA strand, giving off light of a specific
wavelength when illuminated by a laser.
8. The first 10 bases of the DNA molecule being synthesized in this flowgram are:
a) 5’-TACGTACTTA-3’;
b) 5’-TAAGTACGTA-3’;
c) 5’-TCAGCGTAAG-3’;
d) 5’-CTTACGCTGA-3’;
e) none of the above.
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 to the right,
where a “+” sign indicates growth and a “-” sign
indicates no growth.
Chemical Compounds
Mutant number A B C D E F Z
1
      +
+ +   +  +
2
3
    +  +
4
 +   +  +
+ +  + +  +
5
+ + + + +  +
6
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 could lead to an accumulation in which metabolite in the pathway?
a) E; b) Z; c) B; d) A; e) none of the above.