BIOL. 303 EXAM III 11/24/08
Name________________________________
---------------------------------------------------------------------------------------------------------------------This exam consists of 40 multiple choice questions worth 2.5 points each. On
the separate answer sheet, please fill-in the single best choice for each question.
Please bubble-in your name on the answer sheet, leaving a space between first
and last names. Also, bubble-in the last 5 digits of your social security number
under “ID NUMBER” beginning in the left-most column. Good luck!
--------------------------------------------------------------------------------------------------------------------1.
The genetic code is:
A. ambiguous.
B. overlapping.
C. not degenerate.
D. not truly universal.
2.
Which of the following is true?
A. every amino acid is coded for by a single codon.
B. there are more amino acids than there are codons.
C. every codon codes for an amino acid.
D. each codon in a gene codes for no more than one single amino acid.
3.
AUG is almost always the:
A. intron
B. exon
C. anticodon
D. initiation codon
4.
What property of the genetic code allows the use of several codons for a
particular amino acid?
A. near universality
B. degeneracy
C. non-overlapping codons
D. reading frame
5.
Transcribed regions present in mature mRNA are called ________, while
transcribed regions NOT present in mature mRNA are called ________.
A.
B.
C.
D.
introns; exons
exons; introns
codons; anticodons
anticodons; codons
6.
The lac operon
A. is under negative and positive control.
B. is under positive control only.
C. is normally expressed constitutively.
D. is an example of tissue-specific expression.
7.
In the lac operon, under which of the following conditions will the lac genes be
transcribed at high levels?
A.
B.
C.
D.
low glucose, low lactose
high glucose, low lactose
low glucose, high lactose
high glucose, high lactose
Use the following diagram of the lac operon for questions 8 and 9:
(I = lac repressor gene; Z, Y, A = lac operon structural genes; P = lac promoter; O = lac
operator)
I
P
O
Z
Y
A
8. Where would the lac repressor be bound in a (nonmutant) E. coli cell that is growing
in low glucose and high lactose?
A. P
B. O
C. P and O
D. the repressor would not be bound
9. Which parts of the DNA region shown in the diagram encode proteins?
A. P
B. P, O, Z, Y, A
C. I, Z, Y, A
D. I, P, O, Z, Y, A
10.
RNA polymerase binds to the:
A.
B.
C.
D.
operator
promoter
repressor
inducer
11.
With regards to the trp operon,
A. tryptophan is an inducer.
B. tryptophan is a co-repressor.
C. attenuation can halt replication.
D. none of the above.
12.
Under the system of genetic control of the trp operon,
A. when there are high levels of tryptophan in the medium, transcription of the
trp operon occurs at high levels.
B. when there is no tryptophan in the medium, transcription of the trp operon
occurs at high levels.
C. when there are high levels of tryptophan in the medium, transcription of CAP
occurs at high levels.
D. when there are high levels of tryptophan in the medium, ribosomes “stall” and
reduce the levels of tryptophan synthesized.
13.
Regarding the trp operon in B. subtilis, TRAP influences gene expression
A.
B.
C.
D.
14.
by blocking transcription when levels of tryptophan are high.
by inducing transcription when levels of tryptophan are high.
by inducing translation when levels of tryptophan are high.
none of the above
When it comes to the arabinose operon, the AraC protein exerts
A. negative control
B. positive control
C. both negative and positive control
D. no control
15.
Three posttranscriptional modifications often seen in the maturation of mRNA in
eukaryotes are
A.
B.
C.
D.
5'-capping, 3'-poly(A) tail addition, splicing
3'-capping, 5'-poly(A) tail addition, splicing
removal of exons, insertion of introns, capping
5'-poly(A) tail addition, insertion of introns, capping
16.
Considering the location of genetic material in the interphase nucleus, certain
chromosomal territories appear to exist. Specifically,
A. each chromosome appears to occupy a discrete domain.
B. gene-poor regions of chromosomes are located outside the nucleus, whereas
gene-rich regions are located inside the nucleus.
C. even-numbered chromosomes are located in the interior of the nucleus,
whereas odd-numbered chromosomes are located peripherally.
D. large chromosomes are more likely to be located in the center of the nucleus.
17.
Transcription factors act as
A. cis-acting regulatory elements
B. trans-acting regulatory elements
C. promoters
D. enhancers
18.
SWI-SNF proteins are involved in:
A.
B.
C.
D.
basal translation
RNA interference
repression
chromatin remodeling
19.
Eukaryotic cells are able to carefully regulate precise levels of transcription in
specific genes encoding proteins through:
A. complex enhancer elements that can associate with multiple activator and
repressor proteins
B. production of different types of sigma factors
C. attenuation
D. all of the above
20.
Which of the following methods of regulation is not present in prokaryotes?
A.
B.
C.
D.
DNA-binding proteins
attenuation
repressor proteins
chromatin remodeling
21.
Which of the following can account for multiple proteins from a single primary
transcript?
A. alternative splicing
B. reverse transcription
C. 5' methylation
D. polyribosomes
22.
The term "chromatin remodeling" refers to
A. alteration of chromatin structure in association with transcription.
B. a process that only bacteria perform since they contain no nucleus.
C. a process that is exclusively associated with transcription by RNA polymerase
III in eukaryotes.
D. alteration in chromatin structure to facilitate loading and translation by
ribosomes and, thus, enhance gene expression.
23.
The phenomenon known as “RNAi” (RNA interference) is commonly used
experimentally to
A.
B.
C.
D.
reduce expression of a specific target gene.
reduce transcription rate from an entire genome.
interfere with replication.
enhance gene expression.
24.
Controls that link the integrity of the genome with progression through the cell
cycle are known as:
A. growth factors
B. receptors
C. cyclins
D. checkpoints
25.
Colonization of distant sites by cancer cells that break free from a tumor is
known as:
A. metastasis
B. angiogenesis
C. clonal replication
D. apoptosis
26.
Genes that typically contribute to cancer through increased expression are:
A. tumor suppressor genes
B. oncogenes
C. CDK inhibitors
D. nonexistent
27.
Genes that typically contribute to cancer through a loss-of-function mutation are:
A.
B.
C.
D.
tumor suppressor genes
oncogenes
proto-oncogenes
cyclin-dependent kinases
28.
Sporadic cancer arises from __________; familial cancer arises from
_________.
A. somatic mutations; germline mutations alone.
B. somatic mutations; germline mutations in combination with additional somatic
mutations
C .germline mutations; somatic mutations
D. germline mutations; stem cell mutations
29.
What is the name of the protein that helps to regulate multiple checkpoints
throughout the cell cycle and is also known as the “guardian of the genome?”
A. p34
B. p102
C. cyclin
D. p53
30. A person born with an inherited predisposition to cancer usually does not develop
cancer until after
A.
B.
C.
D.
31.
exposure to radiation.
LOH of the inherited mutation.
age 70
Mardis Gras
The "Philadelphia chromosome"
A. is a movie starring Tom Hanks.
B. is a specific translocation implicated in chronic myelogenous leukemia.
C. results from a gene amplification event.
D. is an example of overexpression of an oncogene that is otherwise unaltered.
32.
Regarding the relationship between viruses and cancer, which statement is most
accurate?
A. viruses cause some cancers in animals, but viruses are not associated with
cancer in humans.
B. most human cancers are known to be caused by viruses.
C. viruses are not associated with cancer in animals or humans
D. some human cancers are closely associated with viral infection and some
cancers can possibly be prevented by vaccination against virus.
33.
Two especially useful characteristics for a cloning vector to have are
A. lots of cloning sites and an antibiotic resistance gene.
B. virulence and antigenicity.
C. ability to integrate into the host chromosome and then cause death.
D. reverse transcriptase and ligase activities.
34.
Which of the following is not needed in order to amplify a DNA fragment by
PCR?
A. a set of primers.
B. knowledge of the complete nucleotide sequence of the fragment to be
amplified.
C. a DNA polymerase.
D. deoxynucleotides.
35.
What information is present in a cDNA library?
A.
B.
C.
D.
36.
intron sequences
promoter sequences
exon sequences
telomere sequences
Nucleic acid blotting is widely used in recombinant DNA technology. In a
Southern blot one generally
A. hybridizes filter-bound DNA with a DNA probe.
B. hybridizes filter-bound RNA with a DNA probe.
C. examines amino acid substitutions with radioactive probes.
D. cleaves RNA with restriction endonucleases.
37.
What is the function of dideoxynucleotides in Sanger DNA sequencing?
A. They act as primers for DNA polymerase.
B. They act as primers for reverse transcriptase.
C. They cut the sequenced DNA at specific sites.
D. They stop synthesis at a specific site, so the base at that site can be
determined.
38 .
The two general approaches to sequence a genome are known as
A. “Watson” and “Crick”
B. “Shotgun” and “clone-by-clone”
C. “Southern” and “Northern”
D. SNPs and CNVs
39
Based on the most recent analysis of the sequence of the human genome, which
is closest to the estimated number of human genes?
A. 2,000
B. 20,000
C. 100,000
D. 500,000
40.
Compared to prokaryotic chromosomes, eukaryotic chromosomes in general
A. are larger
B. have interrupted genes
C. display lower gene density
D. all of the above
Happy
Thanksgiving!
ANSWER KEY
Q: 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,
A: D, D, D, B, B, A, C, D, C, B, B, B, A, C, A, A, B, D, A, D, A, A, A, D, A, B, A, B, D,
Q: 30,31,32,33,34,35,36,37,38,39,40
B: B, B, D, A, B, C, A, D, B, B, D