Zoo/Bot 3333
Genetics
Quiz 4
11/22/10
For answers to the quiz, click here:
1. The pufferfish, Fugu has a relatively small genome for a vertebrate, with a haploid genome size of about
380 Mb. If this genome is digested with AvaII (an enzyme with the recognition sequence:
5’-GG(A or T)CC-3’
approximately how many DNA fragments would be produced, assuming equal and random frequencies of
the four nucleotides?
a) 1.25 x 107; b) 1.35 x 106; c) 7.4 x 105; d) 9.3 x 104; e) 5.8 x 103.
2. A kan r tet r plasmid is treated with the restriction enzyme BglI, which cleaves inside the kanamycin
(kan) 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) kan s either tet s or tet r.
Questions 3-4 pertain to the following
experiment. Four pairs of PCR primers were
used to amplify DNA isolated from one man's
somatic cells, and from 21 single sperm that he
donated for this study. Each primer pair
amplifies a different region of the human
genome, referred to as genes A, B, C and D.
Each of these amplified regions was then
divided into 8 aliquots (i.e. 8 identical
subsamples) and these 8 DNA samples were
denatured and spotted onto membrane strips for
nucleic acid hybridization analysis, as shown in
the figure at the right. The membranes were
hybridized to 8 different oligonucleotide probes,
which are designed to distinguish singlenucleotide base differences in the DNA. The
paired oligonucleotides A1/A2, B1/B2, C1/C2
and D1/D2 are 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).
3. Based on the results shown, which gene(s) could be on the Y chromosome?
a) A; b) B; c) C; d) D; e) more than one of the above.
4. Which gene(s) must be autosomal and homozygous for a particular ASO?
a) A; b) B; c) C; d) D; e) more than one of the above.
Questions 5-6 pertain to the
following: DNA studies performed
on a large family show an autosomal
dominant disease of late onset
(approximately 40 years of age). A
genomic DNA sample from each
family member is digested with the
restriction enzyme Taq1, run on an
electrophoretic gel, and subjected to
Southern blot analysis. The probe used in this instance is a DNA fragment linked to the disease gene. The
autoradiogram of this blot is shown above, aligned with the family pedigree.
5. True or false. Since the array of genes in a DNA molecule is a species characteristic, all humans contain
an identical TaqI restriction fragment pattern.
-
6. In the above example, which of the following hybridizing fragments are physically linked to the wild
type allele in individual I-2?
a) 2 kb fragment only; b) 3 kb fragment only; c) both the 2 and 3 kb fragments; d) 5 kb fragment; e) all
three of the above fragments.
G
A
T
C
C
Consider the DNA sequencing gel on the left, produced using the dideoxy
method. Electrophoresis was run as shown on the figure, with the open slots
representing the origin.
7. Which of the above lanes (left to right) on the electrophoresis gel
represents a sequencing reaction containing deoxyadenosine triphosphate?
a) the “G” lane; b) the “A” lane; c) the “T” lane; d) the “C” lane, e) all of the
above.
+
8. The DNA sequence of the TEMPLATE strand reads:
a) 5’-GGTAACAGTATC-3’; b) 5’-CCATTGTCATAG-3’;
c) 5’-CTATGACAATGG-3’; d) 5’-GATACTGTTACC-3’;
e) 5’-GGAAATTTTCCC-3’.
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

+


+
+
Chemical Compounds
B 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.