ZOO/BOT 3333
GENETICS
Exam #4
For answers to the practice exam, click here:
Practice Examination
Name________________________________
A. True/False and multiple choice questions (2 points each). Please fill in your answers on the
scantron sheets provided. For true/false questions, please indicate whether a statement is true (a) or false
(b), or, for multiple choice questions, circle the letter representing the single best choice. If a question seems
ambiguous to you, please raise your hand and I will try to clarify the source of ambiguity.
1. A genetic entity that has a DNA genome, binds to a cellular receptor, integrates into the host cell's
genome and is passed to daughter cells during host chromosome replication and cell division is:
a) a virulent bacteriophage; b) a temperate bacteriophage; c) a plasmid; d) a retrovirus; e) none of the above.
2. Which of the following properties are associated with the enzyme telomerase?
a) may disappear as cells age and go through numerous replication cycles; b) requires an RNA molecule for
its designated activity; c) catalyzes the synthesis of a tandemly repeated DNA sequence; d) all of the above;
e) none of the above.
3. True or false. A peptide bond forms between the amino group of one amino acid and the amino group of
a second amino acid.
4. The molecule hemoglobin is a 4 subunit protein containing two copies each of the products of the alpha
and beta globin genes. Which levels of protein structure are evidenced for the assembly of hemoglobin?
a) primary structure; b) secondary structure; c) tertiary structure; d) quaternary structure; e) all of the above.
5. Which of the following single-stranded DNA sequences contains ONLY pyrimidines?
a) ATATAT; b) GCGCGC; c) ACACACAC; d) CTCCTCT e) none of the above.
6. The enzyme that produces a short RNA molecule that permits the synthesis of an Okazaki fragment is:
a) a primase; b) a ligase; c) a transcriptase; d) a helicase; e) a basketcase.
Questions 7-8 pertain to the following figure, a schematic diagram of rolling circle DNA replication:
C
D
A
B
7. Which of the above represents the 3’ end of a DNA molecule?
a) A only ; b) B only; c) A and B; d) C only; e) B and D.
8. Which of the above ends would represent a site of lagging strand synthesis?
a) A only ; b) B only; c) A and B; d) C only; e) B and D.
9. Which of the following techniques uses mRNA as the source material for recovering cloned molecules?
a) genomic library construction; b) cDNA library construction; c) PCR; d) nuclear transplantation; e) none of
the above.
2
10. Which of the following are essential features of a plasmid used for recombinant DNA cloning?
a) origin of replication; b) ability to integrate into bacterial chromosomes; c) ability to cause lysis of the host
cell; d) all of the above; e) none of the above.
Questions 11-13 pertain to the following. Six independently derived mutants are recovered in Neurospora
which are all unable to grow unless supplemented with compound Z. The mutants are then grown on
minimal media supplemented with one of 6 chemicals all believed 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
precursors added to minimal medium
A
B
C
D
E
F
Z
1
-
-
+
-
+
+
+
2
+
-
+
-
+
+
+
3
-
-
-
-
+
-
+
4
+
+
+
-
+
+
+
5
-
-
-
-
-
-
+
6
+
+
+
+
+
+
+
7
-
-
-
-
+
+
+
11. From the above data, the biochemical pathway leading to Z is:
a) FCDZ; b)DBACFEZ; c) DCFEZ;
d)BCDEFAZ; e)FBACDEZ.
12. From the above data, the gene encoding the enzyme responsible for producing compound E is mutant in
strain:
a) 1; b) 2; c) 3; d) 5; e) 7.
13. Relative to wild type, which of the following mutations might be expected to accumulate high levels of
compound A?
a) 1; b) 4; c) 5; d) 6; e) 7.
3
Questions 14-16 relate to the following diagram, which represents a region of a DNA sequencing gel
produced using the Sanger chain termination technique. The individual lanes represent the reaction products
from the four separate labeling reactions which were loaded at the top of the gel (A,G,C,T):
A
G
C
T
14. Reading 5’ to 3’, the DNA sequence of the strand
being synthesized in this procedure is:
a) GCATGTGTACGC; b) CGTACACATGCG; c)
GCGTACACATGC; d) CGCATGTGTACG;
e) AAAGGGCCCCTT.
15. In this gel, the nucleotide which would lie closest to
the priming site is:
a) an A; b) a T; c) a C; d) a G.
16. For the “T" reaction lane, which of the following
molecules were not present in that specific DNA
synthetic reaction?
a) dATP; b) dCTP; c) dTTP; d) ddTTP; e) all of the above were present in the reaction.
17. A mutation in the rII locus of phage T4 is isolated. This mutant does not revert to wild type. In addition, it
fails to complement several different mutations found in both the rIIA and rIIB genes. This mutation is most
likely:
a) a missense mutation; b) a nonsense mutation; c) the addition of a single nucleotide; d) a deletion; e) all of
the above are equally likely.
.
18. A branched biochemical pathway in a bacterium synthesizes two related essential amino acids D and F:
A mutant defective for enzyme 1 will grow on minimal medium plus:
2
A
1
C
4
D
B
3
E
5
F
a) A alone; b) B alone; c) C alone; d) E alone; e) Both C and E would be required.
19. The following diagram represents a fragment of a gene, where the upper strand is the template strand:
5’-ATTGCC-3’
3’-TAACGG-5’
The RNA produced from this template would be:
a) 5’-AUUCGG-3’; b) 5’-UAACGG-3’; c) 3’-AUUGCC-3’; d) 5’-UAACGG-3’; e) 5’-GGCAAU-3’.
20. A new restriction enzyme is discovered that recognizes a 4 base recognition sequence. Approximately
how many fragments of the Wombat genome (2.6 x 106 bp in size) would you expect if you digested with this
enzyme and the Wombat genome?
a) 100; b) 1000; c) 10,000; d) 100,000; e) 1,000,000.
4
B. Match and Identify (2 points each). Please match the following terms in part I with the appropriate
definitions, characteristics or specific examples, given in Part II. For each term, provide the single best
answer; no term in part II should be used more than once.
part I.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
FISH
temperature sensitive mutations
microarray
beta sheet
retrovirus
R Groups
topoisomerase
3
H-dTTP
transposons
hot spots
part II.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
there are twenty of these found in proteins
non-random in distribution, they can also vary dependent on mutagen treatment
common form of protein secondary structure
protein involved in relieving torsional stress during DNA synthesis
used to visualize the bacterial chromosome by autoradiography
copia elements are an example in Drosophila
oligonucleotide grid used to monitor gene expression
“slow or fast stop” phenotypes provided clues to gene function during bacterial DNA replication
HIV is an example
fluorescent hybridization technique used to localize different genes in the same experiment
5
C. Short Problems (15 points). Please answer the following problems. Be sure to show all work (eg.
calculations); partial credit can only be assigned on the basis of work shown.
1. (7 points). In a mutant hunt, ten adenine-requiring mutations in yeast were obtained and a
complementation test revealed the following results. A “+” indicates complementation, a “-“ indicates no
complementation, and a box indicates that the experiment was not performed.
mutant
1
2
3
4
5
6
7
8
9
10
1

2
+

3

+

4

+


5
+
+
+
+

6
+
+
+
+
+

7

+

+
+

8
+
+
+
+

+
+

9
+
+
+
+

+
+

10
+
+
+
+

+
+


From the above data, how many different genes appear to be associated with the adenine-requiring
phenotype?
From the above data, what mutations represent genetic lesions in the same gene (i.e. cistron)?
Three of the complementation tests were not performed. On the basis of the other results, predict whether
complementation (+) or non-complementation (-) would be observed in these cases.
6
C. Short Problems (15 points). Please answer the following problems. Be sure to show all work (eg.
calculations); partial credit can only be assigned on the basis of work shown.
Gene Q
Gene R
Gene S
Gene T
1. (7 points). Pairs of PCR primers were
ASO
Q1 Q2
R1 R2
S1 S2
T1 T2
used to amplify DNA isolated from one
Somatic Cell







man's somatic cells, and from 20 single
Sperm number
sperm that he donated for this study.
1



Each primer pair amplifies a different
2




region of the human genome, referred to
3



as genes Q, R, S and T. Each of these
4




amplified regions was then divided into 8
5



aliquots (i.e. 8 identical subsamples) and
6




7



these 8 DNA samples were denatured
8



and spotted onto membrane strips for
9




nucleic acid hybridization analysis, as
10




shown in the figure at the right. The
11



membranes were hybridized to 8 different
12




oligonucleotide probes, which are
13



designed to distinguish single-nucleotide
14




base differences in the DNA. The paired
15



oligonucleotides Q1/Q2, R1/R2, S1/S2
16




17



and T1/T2 are therefore regarded as
18



allele-specific oligonucleotide probes
19




(ASOs). A black circle on the diagram
20




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).
In the space below indicate which gene(s) could be X-linked, and give a brief justification for your answer.
Which, if any, of these regions could be on the Y chromosome?
.
In the space below indicate the genes that are autosomal and appear to be located either on different
chromosomes or far apart on the same chromosome. Give a brief justification for your answer.
Do any of the genes look as if they are linked to one another? If so, estimate a map distance between the
two loci.