GENETICS - BIOL 7 EXAM IV - December 17,
2002 NAME:
DO NOT USE ANY OTHER PAPER AT ANY TIME WITHOUT INSTRUCTOR PERMISSION
Part I: [76 points] 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 pt
each Note extra questions for bonuses
keep
your eyes open!
1. 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
2. Genes encoding enzymes are called
a. structural genes
b. primary genes
c. enzymic genes
d. polycistronic genes
e. genes encode proteins, not enzymes
3. Trans-acting factors
a. are regions of DNA that move
b. are regulated independently of the genes
they regulate
c. are always polypeptides
d. in prokaryotes, are encoded by genes
coordinately regulated in an operon
e. are never regulated
4. Which of the following is NOT one of the Hardy-Weinberg
assumptions?
a. there are no mutations that create new
alleles
b. there is no migration into or out of the
population
c. the individuals in the population mate at
random
d. the population is small
e. there is no selection
5. If two organisms appear to be the same, except that one can
tolerate higher temperatures than the other, what conditions should be
used to study the gene(s) involved in temperature tolerance?
a. cool temperatures where both organisms
thrive; use some other stressful condition (not temperature)
b. warm temperatures where both organisms
thrive
c. very warm temperatures where one organism
thrives but the other barely survives
d. hot temperatures where one organism
survives but the other dies
e. extremely hot temperatures which kill both
organisms, but one survives longer than the other
6. The transcription termination signal(s) in E. coli is/
are
a. hairpin loop and absence of trp
b. hairpin loop and rho
c. rho and absence of trp
d. there is only one signal: hairpin loop
e. UGA, UAA, AAG termination codons
7. A mutation in the gene encoding phenylalanine tRNA synthetase
results in charging phe onto tRNApro. The effect of this mutation would
be
a. unobservable
b. lethal
c. minor - the cell would be less healthy
d. compensated by a mutation that charges
proline onto tRNAphe
e. other:______
8. Elongation by the E. coli RNA polymerase is accomplished
by
a. alpha subunits(α2)
b. beta & beta' subunits (ββ')
c. rho subunit (ρ)
d. sigma subunit (σ)
e. a and b
f. a, b, and c
g. a, b, and d
h. a, b, c, and d
9. One consequence of the Hardy-Weinberg Law is that
a. genetic variability is stably maintained in
a population
b. dominant traits increase in frequency from
one generation to the next
c. allele frequencies change constantly in a
population
d. knowing the frequency of one genotype will
tell you nothing of the other genotypes
e. heritability
10. Sigma factor is the RNA polymerase subunit which
a. determines which regions of DNA will be
transcribed
b. determines where RNA pol will bind DNA
c. determines the site of transcription
termination
d. a and b
e. all of the above
11. When experimental data do not fit the predicted result, and
p<< 0.05,
a. the hypothesis is proved false
b. the hypothesis is proved true
c. the hypothesis may be true, but the most
likely interpretation is that it needs revision
d. the experiment was done improperly, and
must be repeated
e. the analysis was incorrect and must be
recalculated
12. An F' bacterial strain is established when
a. an F- becomes a recipient
b. an F+ becomes a donor
c. an F plasmid integrates into the host's
chromosome
d. an F plasmid incorporates host DNA when it
leaves the chromosome
e. an F- becomes an F+
13. An operon is a group of structural genes that
a. encode the subunits of a single protein
b. only function in the presence of an inducer
c. are under the control of a single promoter
d. only exist in E. coli
e. only function in the presence of CAP
14. To stimulate transcription of the lac operon, CAP must be bound to
a. promoter
b. cAMP
c. glucose
d. a and b
e. all of the above
15. Mutation of a consensus sequence
a. decreases its activity
b. increases its activity
c. does not affect its activity, as long as it
is still recognizable
d. a or b but not c could occur
e. any of the above could occur
16. Hfr 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
17. If a DNA sequence is known, one can infer the:
a. RNA encoded sequence
b. polypeptide's amino acid sequence
c. polypeptide function
d. a and b
e. none of the above
What is entailed? What would an investigator do to make the
feasible inference(s)? Why can the other(s) not be
made? 18. Which of the following techniques can NOT be used to
map genes?
a. trihybrid testcrosses
b. dihybrid testcrosses
c. Hfr-mediated conjugation
d. lytic (the infected cell is killed quickly)
phage infection
e. phage complementation
19. An Hfr bacterial strain is established when
a. an F- becomes a recipient
b. an F+ becomes a donor
c. an F plasmid integrates into the host's
chromosome
d. an F plasmid incorporates host DNA when it
leaves the chromosome
e. an F- becomes an F+
20. The entirety of an individual's genotype, including known and
unknown genes, is the
a. genetic milieu
b. complementation
c. pleiotropy
d. familiality
e. quantitative variation
21. A mutation which makes the lac repressor unable to bind
operator would result in _____ compared to normal
a. low levels of lac transcription under all
conditions
b. high levels of lac transcription under all
conditions
c. low levels of lac transcription in low
glucose only
d. high levels of lac transcription in low
glucose only
e. high levels of lac transcription in high
glucose only
22. Detectable mutations would probably occur more often if
a. the genetic code were not degenerate
b. DNA pol III had no 3'-5' exonuclease
activity
c. the genetic code were an overlapping code
d. a and b
e. all of the above
23. A product which is always made, regardless of changes in the
environment is
a. protein
b. constitutive
c. facultative
d. inducible
e. auxotrophic
24. The Hardy-Weinberg formula can be used
a. to estimate allele frequency if phenotype
frequency is known
b. to estimate phenotype frequency if allele
frequency is known
c. a and b are true under all conditions
d. a and b are true only for populations in
equilibrium
e. all of the above
25. The transcription product of a set of contiguous genes in an
operon
a. is a polycistronic mRNA
b. is a single protein
c. are many different mRNAs
d. is a regulatory protein
e. is a cistron
26. If an amino acid sequence is known, one can infer the:
a. DNA coding sequence
b. RNA coding sequence
c. polypeptide function
d. a and b
e. none of the above
What is entailed? What would an investigator do to make the
feasible inference(s)? Why can the other(s) not be
made? 27. Attenuation involves
a. nascent mRNA tertiary structure interacting
with the DNA template
b. nascent mRNA self-destruction
c. tRNAs binding the template DNA
d. transcription from the antisense strand of
the DNA
e. an attenuator polypeptide product
inhibiting further transcription
28. A mutation which makes the lac repressor unable to release
bound operator would result in __________ compared to normal:
a. high levels of lac transcription under all
conditions
b. low levels of lac transcription under all
conditions
c. high levels of lac transcription in low
glucose only
d. low levels of lac transcription in low
glucose only
e. high levels of lac transcription in high
glucose only
29. 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
30. 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
31. DNA sequences which can replicate autonomously or be
integrated into the host cell genomic DNA are called
a. plasmid
b. operon
c. episome
d. cistron
e. replicon
32. "Cistron" means
a. regions of DNA which can not complement
each other
b. several genes regulated by one promoter
c. all of the genes comprising a single
plasmid or bacteriophage DNA
d. the message transcribed from a structural
gene
e. regions of DNA which can not recombine with
each other
33. Polycistronic mRNAs are the transcription products of all
a. prokaryotic genes
b. eukaryotic genes
c. prokaryotic operators
d. adjacent genes under the control of a
single promoter
e. adjacent genes
34. Do geneticists still map genes by controlled crosses and
pedigree analysis?
a. YES, it is the only way to map genes in
eukaryotes
b. YES, it is often used in conjunction with
DNA sequencing and RFLP analysis
c. NO, DNA sequencing and RFLP analysis is
used by itself
d. NO, these old-fashioned methods are tedious
and completely outmoded
e. NO, these methods never worked anyway.
35. The E. coli genetic map is (classically) measured in
a. seconds
b. minutes
c. hours
d. base-pairs
e. degrees
Why? What does the unit mean; to what does it refer? 36. A
genetic marker
a. is used only for RFLP 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. In order to map genes one must
a. sequence DNA
b. mate large numbers of individuals with
known genotypes
c. have a chromosomal library
d. measure recombination rates between genes
during meiosis
e. any of the above may contribute to a gene
map
38. 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
39. 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. complementation can be observed
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
40. Exchange of genetic material that requires direct contact
between bacterial cells is
called ; that which requires
a phage is .
a. transduction ... transformation
b. transduction ... conjugation
c. conjugation ... transduction
d. conjugation ... transformation
e. transformation ... transduction
41. The lac operon responds to high lactose when allolactose
binds to
a. repressor protein, which then dissociates
from operator DNA
b. promoter DNA, which initiates transcription
c. CAP which initiates transcription
d. operator DNA, causing a conformational
change which initiates transcription
e. repressor protein, causing it to bind
operator DNA tightly
42. During transcription termination in E. coli what subunits are
found associated with the core RNA polymerase?
a. sigma
b. rho
c. gp28
d. sigma and rho
e. none of the above
43. The lac operon is
a. inhibited by an excess of lactose
b. inducible and under negative control (off
unless turned on)
c. repressible and under positive control (on
unless turned off)
d. part of the glucose operon
e. stimulated by glucose
44. In the presence of lactose and the absence of glucose the lac
repressor is _______ and CAP is ________ to the lac operon DNA
a. bound ... not bound
b. bound ... bound
c. not bound ... bound
d. not bound ... not bound
e. neither ever binds lac operon DNA 45.
In the lac operon, the inducer binds to
a. repressor protein, causing it to bind
operator DNA tightly
b. promoter DNA, which initiates transcription
c. CAP which initiates transcription
d. operator DNA, causing a conformational
change which initiates transcription
e. repressor protein, which then dissociates
from operator DNA.
46. During transcription initiation in E. coli what subunits are
found associated with the core RNA polymerase?
a. sigma
b. rho
c. gp28
d. sigma and rho
e. none of the above
47. During transcription elongation in E. coli what subunits are
found associated with the core RNA polymerase?
a. sigma
b. rho
c. gp28
d. sigma and rho
e. none of the above
48. The positive effector of the lac operon is
a. CAP
b. cAMP
c. CARP
d. a and b
e. all of the above
49. An operon is a group of structural genes that
a. encode the subunits of a single protein
b. only function in the presence of an inducer
c. only function in the presence of CAP
d. only exist in E. coli
e. are under the control of a single promoter
50. The Hardy-Weinberg Law states that
a. in a large, randomly mating population,
allele frequencies do not change
b. in a large, randomly mating population,
allele frequencies change
c. in a small, randomly mating population,
allele frequencies do not change
d. in a small, randomly mating population,
allele frequencies change
e. none of the above
51. Human gene mapping can NOT be done using which of the
following?
a. DNA sequencing
b. complementation analysis
c. karyotype analysis
d. pedigree analysis
e. analysis of offspring from selected matings
52. Which of the following represents a clone?
a. a bacterial colony
b. the fish in a school
c. siblings in a human family
d. siblings from a Drosophila mating
e. all of the above
53. In an operon encoding a polycistronic message, a downstream
effect is seen when
a. X+Y- phenotype is the same as X-Y-
b. X-Y- phenotype is the same as X-Y-
c. X-Y+ phenotype is the same as X-Y-
d. X-Y+ phenotype is the same as X+Y+
e. X+Y- phenotype is the same as X+Y+
explain how a downstream effect might occur: 54. Genetic
equilibrium is
a. any change in allele frequency due to chance
b. change of allele frequency due to organisms
moving from one population to another
c. allele frequencies tending toward
Hardy-Weinberg proportions
d. the proportion of one allele in a population
e. the result of natural selection
55. Conjugation in E. coli requires
a. the F plasmid to be autonomous in the
cytoplasm
b. a group of F genes to be present in the
donor but not the recipient
c. an autonomous origin of replication
d. integration of the F plasmid ito the host
chromosome
e. the F (fertility) gene product
56. During F+ 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
57. During F' 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
58. 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
59. After completion of conjugation, the donor cell
a. is no longer F+
b. has lost some of its genome, and dies
c. becomes Hfr
d. remains unchanged
e. it depends on which sort of conjugation
took place
For #s 60 - 68 , use the following key to indicate the phenotype
expected from the indicated strains of E. coli.
no lactose
lactose
a. +
+
b. -
+
c. -
-
d. +
-
e. none of the above OR not enough information given
if (e): bonus for correct answer: write it
β-galactosidase
permease
next to
the genotype
a
a
60. I+ Oc Z+ Y+
a
a
61. I- O+ Z+ Y+
c
b
62. I+ O+ Z- Y+
c
c
63. Is O+ Z+ Y+
c
c
64. Is O+ Z- Y+
b
b
65. I+ O+ Z+ Y+
a
c
66. F' Is Oc X+ Y- / I- O+ Z+ Y+
b
b
67. F' I- O+ Z+ Y- / I+ O+ Z- Y+
b
a
68. F' I- O+ Z+ Y- / I+ Oc Z- Y+
69. A merozygote
a. always occurs as a result of conjugation
b. occurs only as the result of conjugation
c. is a partial diploid
d. always has a different phenotype from its
"parents"
e. undergoes meiosis
70. The lac repressor
a. is active unless bound to DNA
b. is active unless bound to lactose (or its
derivatives)
c. allows transcription of the lac operon to
occur only when lac is required
d. binds the promoter
e. binds CAP
71. The trp repressor
a. is active unless bound to DNA
b. is active unless bound to tryptophan (or
its derivatives)
c. allows transcription of the trp operon to
occur only when trp is required
d. binds the promoter
e. binds CAP
72. 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
73. Which of the following is important for regulation of gene
expression?
a. transcription of mRNA
b. translation of mRNA
c. degradation of mRNA
d. transport of mRNA
e. all of the above
74. The fertility plasmid of E. coli
a. confers antibiotic resistance
b. is an episome
c. is passed to recipient cells during each
conjugation
d. is a cytoplasmic bridge
e. is a mutant
75. The Hardy-Weinberg Law is based on the premise(s)
a. selctive pressures are not acting
b. mating is random
c. the population is essentially infinitely
large
d. a and b
e. all of the above
76. Plasmids
a. are viral DNA
b. are viral genes which control replication
c. allow conjugation
d. are small pieces of autonomously
replicating DNA
e. occur only in prokaryotes
Part II: [25 points] Omit one. 5 points each.
1. What gene did you look up? Bonus: what is its function, or
what does a mutation at its locus cause? 2. Fill in the
chart to indicate the phenotype expected from the given strains of a
theoretical prokaryotic student species whose study habits are
ordinarily repressed except in the presence of "incentive".
Effective studying requires 2 gene products which control the
phenotypes of individual study (R), and the ability to form study
groups (T). Complete the chart below. How could such a
system be used to demonstrate trans-dominance?
cis-dominance? Explain what these terms mean and show how the
phenomena can be illustrated by adding appropriate experiments to the
chart, and briefly explaining their interpretation.
REVIEW MATERIAL
TEST EACH OTHER
no
incentive
incentive no
incentive incentive
I+O+R+T+ -
+
- +
I+OcR+T+ +
+
I-O+R+T+
+ +
I+O+R-T+
IsO+R+T+ -
-
IsO+R-T+ -
-
- -
3. Why is protein generally considered to be the final product of
gene expression (rather than, e.g., carbohydrates or lipids)? Where do
other biological molecules, like lipids and carbohydrates, come from?
Does the genome control their production - and if so, how?
4. List DNA binding proteins - name them as specifically as
possible. ½ pt each [> 10 is bonus; max 20 ]
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] 5. Map the chromosome from the following interrupted Hfr
conjugation data. Markers are shown in the order they were
donated. Explain what a “strain” is; how were these strains used
to generate the map (in other words - show your work)
strain 1 A
Q R J
strain 2 V
S J R
strain 3 D
B E W
strain 4 S
V M D
strain 5 W
K A Q
strain 6 K
W E B
6. Referring to the graph:
Explain how this information could be used to help
devise conditions for a study of this system, and indicate
what conditions you would use - and why.
Is this system likely to be an experimental
organism, human, or could be either? Explain.