Part I: [ 50 pts ]Choose the one BEST answer. Circle its letter. Read each question and all 5 choices carefully because more than one answer might seem correct at first glance. 1 point each
1. Co-transcriptional translation
permits
a. 5' capping with m7GTP
b. 3' polyadenylation
c. attenuation
d. a and b
e. all of the above
2. Regulation of eukaryotic gene
expression
DOES NOT occur at the level of
a. transcriptional control
b. mRNA processing from a non-translatable
pre-mRNA to a mature mRNA
c. mRNA transport from the nucleus to
the cytoplasm
d. mRNA stability
e. all of the above ARE used
3. Promoters are
a. DNA nucleotide sequences that serve
as recognition sites for RNA pol binding
b. DNA loci necessary for correct transcription
initiation
c. located at a fixed distance from the
site of transcription initiation (not at the site)
d. immediately adjacent to the gene(s)
they regulate
e. all of the above
4. Polyadenylation of the primary
transcript
occurs
a. in the nucleus
b. in the cytoplasm
c. at the nuclear membrane
d. a and b
e. all of the above
5. Histone 1 (H1) is associated most
directly
with
a. nucleosome
b. octamer
c. ribonucleoprotein
d. small nuclear ribonuclear protein
e. linker DNA
6. In eukaryotes, transcription takes
place in the
a. any chromatin
b. nucleosome
c. euchromatin
d. heterochromatin
e. solenoid
7. In E.
coli, in the presence of glucose, cAMP levels are and
a. decreased and catabolite repression
occurs
b. decreased and catabolite repression
does not occur
c. increased and catabolite repression
occurs
d. increased and catabolite repression
does not occur
e. cAMP is not affected by glucose levels,
but rather, by lactose levels
8. Elongation by the E.
coli RNA polymerase is accomplished by
a. alpha subunits
b. beta & beta' subunits
c. rho subunit
d. sigma subunit
e. a and b
f. a, b, and c
g. a, b, and d
h. a, b, c, and d
9. All of the following are
cis-acting
elements EXCEPT
a. trp operator
b. trp promoter
c. trp repressor
d. trp attenuator
e. lac promoter
10. 3' polyadenylation protects the
mRNA
from
a. endonuclease degradation
b. exonuclease degradation
c. RNA polymerase degradation
d. RNA transcriptase acylation
e. heteronuclear recomposition
11. Is DNA sequence alone sufficient
to
regulate gene activity?
a. YES, because promoters are specific
DNA sequences
b. YES, because trans-acting factors bind
specific DNA sequences
c. NO; we know this because all cells
in an organism contain the same DNA, but different products are made in
different cell types
d. NO, because histones bind DNA randomly
e. In some organisms, YES; in some, NO
12. Regions 3 & 4 of the trp
attenuator
base pair to form a hairpin loop when
a. trp levels are low
b. trp levels are high
c. cAMP levels are low
d. cAMP levels are high
e. glucose is present
13. In a cell-free transcription
system
testing the components of reconstituted chromatin, relatively low rates
of transcription, randomly initiated, is typical of "chromatin" lacking
a. non-histone chromosomal proteins
b. histones
c. attenuators
d. a and b
e. all of the above
14. Introduction of a DNA fragment
containing
several genes from one bacterium into another cell of a different
strain
can be used to map genes if any of the following is true, EXCEPT
a. the donated DNA is homologous to the
recipent's genome
b. a merozygote is formed
c. the recipient and donor strains share
the same phenotype
d. recombination occurs
e. the phenotype of the recipient strain
is altered
15. Which of the following is a
plasmid?
a. F +
b. F '
c. F -
d. a and b
e. all of the above
16. Which subunit of prokaryotic RNA
polymerase
recognizes the Pribnow box?
a. alpha
b. beta
c. rho
d. sigma
e. beta
17. Transcription of which of the
following
results in polycistronic mRNA?
a. lac operon
b. ara operon
c. trp operon
d. all prokaryotic mRNA is polycistronic
e. a and b
f. a, b, and c
g. all of the above
18. Distances between genetic loci
are
expressed as
a. minutes
b. map units
c. base pairs (or kilo-base pairs)
d. any of these (a, b or, c) - they are
interchangeable units of distance
e. any of these (a, b or, c) - but they
are NOT interchangeable units of distance
19. The trp operon encodes enzymes
involved
in a
a. catabolic pathway
b. anabolic pathway
c. constitutive pathway
d. a and b
e. a and c
20. A lariat is
a. a temporary structure formed during
excision of an intron
b. a DNA sequence that increases the transcriptional
activity of nearby genes
c. a structure involved in rho-independent
termination
d. one of the subunits of RNA polymerase
e. the result of experimentally base pairing
eukaryotic DNA with its transcribed mRNA
21. Enhancers can be distinguished
from
promoters because
a. the position of the enhancer need not
be fixed with respect to transcription initiation site
b. enhancers can be placed upstream, downstream
or within the gene
c. the orientation of an enhancer can
be inverted without significant effect
d. enhancers can be moved to area near
an unrelated gene and that gene will be enhanced
e. all of the above
22. A clone is a
a. bacterial colony
b. all the offspring of a single set of
parents
c. a group of genetically identical
cells or organisms
d. a school of identical fish
e. all of the above are examples of clones
23. A constitutive gene
a. is required for life - any mutation
is lethal
b. is found in all similar of related
organisms
c. regulates the activity of other genes
d. is transcribed continuously regardless
of the chemical makeup of the environment
e. there is no such thing
24. Inducible enzymes
a. are encoded by polycistronic mRNAs
b. only accumulate under certain specific
conditions
c. are catabolic
d. are anabolic
e. are prokaryotic
25. TATA binding protein
a. is part of the RNA pol I complex
b. is part of the RNA pol II complex
c. is part of the RNA pol III complex
d. is so highly conserved that it is found
in both prokaryotes and eukaryotes
e. is cis-acting
26. For maximal transcription of the
lac
operon, which of the following must be present?
a. lactose and CAP
b. lactose, CAP and cAMP
c. glucose and CAP
d. glucose, CAP and cAMP
e. glucose, lactose and CAP
27. Nucleosomes
a. are found primarily on transcriptionally
active DNA
b. are found primarily on transcriptionally
inactive DNA
c. are found primarily on heterochromatic
DNA
d. are found primarily on euchromatic
DNA
e. are fairly evenly distributed throughout
the chromatin
28. Which of the following may occur
in
the formation of a mature mRNA?
a. the exons are removed
b. a poly-A tail is added to the 5' end
c. the introns are removed
d. a cap is added to the 3' end
e. none of the above
29. The Pribnow box
a. is found in eukaryotes and prokaryotes
b. directs initiation of transcription
to occur downstream
c. regulates transcription initiation,
elongation, and termination
d. is found on the RNA pol
e. is found on a ribosome
30. Eukaryotic gene regulation can
occur
via
a. transcriptional control
b. processing of the primary transcript
c. translational control
d. a and b
e. all of the above
31. Trans-acting factors
a. are regions of DNA that move
b. are always polypeptides
c. in prokaryotes, are encoded by genes
coordinately regulated in an operon
d. are regulated independently of the
genes they regulate
e. are never regulated
32. F' cells
a. form when Hfr episomes revert to the
plasmid form
b. can create merozygotes
c. cause recipient F-
cells to become conjugation - competent (F+
phenotype)
d. are E.
coli
e. all of the above
33. RNA polymerase
a. functions in translation
b. transcribes both introns and
exons
c. is a ribozyme
d. starts transcription at the AUG
initiation
signal
e. can synthesize many products at
one
time by forming a nucleosome
34. Gene regulation in eukaryotes can
be regulated by
a. effector molecules
b. molecules originating outside a
cell
c. molecules that form complexes with
cytoplasmic proteins, which then shuttle to the nucleus
d. signals that regulate processing
of
a primary transcript
e. all of the above
35. Which RNA polymerase is
responsible
to tRNA transcription in eukaryotes?
a. RNA pol I
b. RNA pol II
c. RNA pol III
d. RNA pol holoenzyme
e. tRNA is not transcribed in
eukaryotes
36. A genetic marker
a. is used only for mapping analysis
b. is any gene
c. is any DNA sequence which can be
recognized
d. is any gene which results in a
recognizable
phenotype
e. can be found only in eukaryotes
37. Genes encoding enzymes are called
a. structural genes
b. primary genes
c. enzymic genes
d. polycistronic genes
e. genes encode proteins, not enzymes
38. Is it likely that enhancer action
is mediated by soluble molecules?
a. YES,because enhancers are
position
and orientation -independent
b. YES, because enhancers are
trans-acting
elements
c. YES, because enhancers are DNA
sequences
d. NO, because enhancers are DNA
sequences
e. NO, because soluble molecules can
not
bind anything
39. An R-loop
a. is seen when certain eukaryotic
genes
are hybridized with mRNA
b. is seen when certain prokaryotic
genes
are hybridized with mRNA
c. is seen in any DNA hybridized with
mRNA
d. is found naturally in all
eukaryotic
genes
e. is a uniquely human phenomenon
40. The transcription product of a
set
of genes regulated coordinately in a eukaryote
a. is a cistron
b. is a single protein
c. are many different mRNAs
d. is a regulatory protein
e. is a polycistronic mRNA
41. Which RNA polymerase is
responsible
to tRNA transcription in prokaryotes?
a. RNA pol I
b. RNA pol II
c. RNA pol III
d. RNA pol holoenzyme
e. tRNA is not transcribed in
prokaryotes
42. Solenoids
a. are hollow coils of nucleosomes
b. require histone H1
c. are an examples of supercoiling
d. a and b
e. all of the above
43. Polyadenylation occurs
a. in the nucleus during transcription
b. in the nucleus immediately after
transcription
c. during movement from the nucleus
to
the cytoplasm
d. in the cytoplasm
e. all of the above may occur
44. snRNPs
a. are comprised of RNA
b. are comprised of protein
c. are found exclusively in the
nucleus
d. a and b
e. all of the above
45. An exon
a. is DNA which will be "excised" -
removed
from the final product
b. is RNA which will be "excised" -
removed
from the final product
c. is the result of evolutionary
duplication
d. is RNA which will remain in the
final
product
e. self splices
46. An example of a cis-acting
element
is
* a. CAAT box
b. RNA polymerase
c. lac repressor
d. allolactose
e. the gene for the lac repressor
47. The Pribnow box in prokaryotes
and
the TATA and CCAAT boxes in eukaryotes are examples of
a. leader sequences
b. promoters
c. attenuators
d. initiation sequences
e. operators
48. Nucleosomes
a. are hollow coils of DNA
b. are small nuclear bodies found in
certain
primitive eukaryotes
c. are an examples of supercoiling
d. are comprised of DNA and histone
octomers
e. regulate gene expression by
activating
genes
49. F strains differ from each other
because
a. the F episome has become
integrated
in different loci
b. different amounts of DNA are
transferred
during conjugation
c. the F episome had incorporated
different
host sequences when it came out of the host chromosome
d. they are prototrophs
e. they do not differ
50. Heterochromatin is
a. found in the nucleus
b. typically prokaryotic
c. not found in interphase nuclei,
only
in mitosis or meiosis
d. not found in mitotic or meiotic
nuclei,
only in interphase nuclei
e. transcriptionally active
51. During Hfr conjugation, what is
transferred
to the recipient?
a. the information required to
control
conjugation
b. some host chromosomal DNA
c. the F-pilus
d. a and b
e. all of the above
Part II [variable credit]: 1. [ 15pts] Describe the lac and the trp operon. In both cases, two distinct and different regulatory mechanisms (note: do not just describe one mechanism turned on or off) must be described. Explain how the regulation of these two operons integrates with the organism's needs and physiology (why and when the operons are active or inactive); briefly compare and contrast the two systems.
2. [ 4 pts; more is bonus] List DNA binding proteins - name them as specifically as possible. ½ pt each
bonus: Write a question that you studied for, and forgetful me, I neglected to ask. Answer your question. PLEASE ask yourself something you can answer well! PLEASE answer the question you actually ask. [up to 5 points awarded based on question & answer]
Part III: [10 pts each] Answer
3 Be sure that you read the question carefully and answer ALL the
parts.
1. In eukaryotes, mRNA is subject to
several
modifications. Briefly explain the modification, when and where it
occurs,
and its [presumed] major function(s).
a. 5'-cap
b. polyadenylation
c. splicing
2. a. What is a "consensus sequence"?
Explain the significance of this idea. Give at least two specific
examples.
b. Using the following data from Hfr conjugation, map the genes. Why do none of the values ever reach 100%?
3. For each of the following, if it can regulate transcription rate, explain how and give an example of a system in which it is a regulator of gene expression:
a. presence of initiation factors
b. availability of amino acids or of a particular amino acid
c. molecular configuration of an mRNA
d. presence of transcription factors
4. List and distinguish (describe/explain how they differ from each other) 5 RNA polymerases.
5. If we were to look at two different cell types in a single organism, we would find the same genomic DNA, but different genes would be expressed to yield the two distinct tissue phenotypes. Briefly explain what chromatin components are involved in determining the tissue-specific gene activity, and the experimental basis for this model. -- or (in other words) -- How can the expression of related genes be coordinated in eukaryotes? How might it be possible to express a particular gene as a member of one group of genes under one set of conditions but with a different group of genes under another set of conditions. Contrast the eukaryotic model of coordinated gene expression with what you know about prokaryotic regulation.