quizzes (all chapters) Flashcards
(152 cards)
1
Q
In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCartyused an in vitro assay to determine the molecule
responsible for the transformationof bacterial cells, and that the transforming factor could be destroyed by
A
deoxyribonucleases but not by protease or ribonuclease enzymes
2
Q
The classic experiment performed by Alfred Hershey and Martha Chase revealed that:
A
in a bacteriophage, DNA is the hereditary material
3
Q
In 1953, James Watson and Francis Crick proposed the
A
double helix as a model for the structure of DNA
4
Q
There were six important themes of scientific discovery listed in Chapter 1. Beadle and Tatum’s experiment was an example of which of these?
A
study of mutations is a driving force in genetics and in modern molecular biology
5
Q
DNA is the hereditary material: each ________ is a single molecule of DNA, and _________ are sequences of DNA .
A
chromosome, gene
6
Q
Nucleic acids are polymers made up of which of the following monomers ?
A
nucleotides
7
Q
Edwin Chargaff found that the base composition of DNA, defined as the “percent G+C”
- differs among species
- is constant in all cells of an organism within a species
- is the same among all species
- more than one answer is correct
A
more than one answer is correct
8
Q
The abbreviation dNTP stands for
A
deoxynucleoside 5’ -triphosphate
9
Q
What unusual DNA secondary structure would a sequence of DNA containing numerous tandem repeats most likely form?
A
slipped structure
10
Q
Which of the following is TRUE of DNA secondary structure?
A
Includes the major groove, which is more available to interact with DNA binding proteins than minor grooves
11
Q
Where are you likely to find a G-quadruplex structure?
A
telomeres and promoter regions
12
Q
Which statement is not true about DNA supercoiling?
A
negative supercoiling is associated with decreased activity in replication and transcription
13
Q
What is TRUE about DNA supercoiling?
A
- positive supercoiling occurs ahead of replication fork and transcription complexes
- negative supercoiling puts energy into DNA
- DNA in prok/euk exist in the negative supercoiling state
14
Q
A linear DNA molecule containing 25 complete turns (or twists, T=25) with 10.5 base pairs per turn is in a solution. If the double helix is underwound by one full turn to the left and then the ends are sealed together, the result is a strained circle with 11 bp per turn, where L=24 and T=24. If one negative supercoil is spontaneously introduced, the DNA circle will have which of the following characteristics?
A
L=24, T=25, 10.5bp/turn
15
Q
Which enzyme relieves positive supercoiling ahead of the replication fork?
A
topoisomerase
16
Q
Which of the following is TRUE concerning denaturation and renaturation of DNA?
A
DNA may be renatured following denaturation through complementary base pairing
17
Q
Which term below best describes the unusual secondary structure that the following sequence, containing inverted repeats, may exhibit?
5’-GTAACCAGAATATTGTCTTCTGGTACT-3’
3’CATTGGTCTTATAACAGAAGACCATGA-5
A
cruciform
18
Q
The predominant form of DNA in vivo is
A
B-DNA
19
Q
Which of the following is NOT a characteristic of DNA secondary structure?
A
the two strands of DNA run parallel to one another, 5-2’
20
Q
How are the 2 based of DNA stabalized together?
A
base stacking and base pairing
21
Q
Which of the following RNA types is not matched up correctly with its function?
tRNA - Delivers appropriate amino acid to ribosome
snRNA - Repress transposable elements
rRNA - Essential component of the ribosome
miRNA - Post-transcriptional gene regulation
snoRNA - rRNA processing
A
snRNA - Repress transposable elements
22
Q
tRNA
A
delivers appropriate amino acid to ribosome
23
Q
rRNA
A
essential component of ribosome
24
Q
miRNA
A
post transcriptional gene regulation
25
snoRNA
rRNA processing
26
Which type of RNA is the most abundant by number of molecules, in mammalian cells?
tRNA
27
Which of the following is NOT an RNP and was not talked about in the textbook/lecture/PPTs as an RNP?
DNA polymerase
28
RNA can develop unique structures. What structure forms when helix-helix interaction in minor grooves are stabilized by hydrogen bonds occurring between the 2'-OH of a ribose in one helix with a base on another helix?
ribose zipper motif
29
What are catalysts made from RNA called as a group?
ribozyme
30
Which of the following statements about tRNA is NOT true?
tRNAs may contain only 1 type of modified base, called pseudouridine.
31
Which of the following statements about tRNA IS true?
- tRNA loops have separate function
- 2D structure of tRNA is a cloverleaf
- recognized by special proteins that add AA to the attachment site
- base paired stems are often involved in long range interaction with other stems by coaxial stacking
32
There is a tremendous versatility of functional RNA products involved in a wide range of cellular processes. One of the key contributing factors to this versatility is
ability of RNA to form unique 3D structures to act similary to proteins
33
Heterogenous nuclear ribonucleoproteins are
chaperones that help mRNA fold correctly
34
Which of the following is NOT true of RNA-based genomes?
many bacteria have RNAbased genomes
35
Which of the following IS true of RNA-based genomes?
- high mutation rate in DNA based genomes
- small genome size
- many RNA viruses do not have DNA intermediate
36
_____________ different genetically-encoded amino acids are found in the proteins of cells; they are distinguished by___________________ .
22, the composition of their side chains or R groups
37
Which amino acid shown below would be more likely to be found within the membrane region of a transmembrane protein, and less likely to be found in the intracellular region?
alanine
38
The sequence of amino acids that make up a polypeptide chain describes
primary
39
26S rRNA is a true catalyst. It is not changed in the overall process of splicing that was studied by Thomas Cech and colleagues.
false
40
The site of many post-translational modification of the histone proteins is the
charged tails at N-terminal end
41
Brief digestion of eukaryotic chromatin with micrococcal nuclease gives a visible ladder of bands on an agarose gel separated from each other by multiples of ~180 bp. The fragment size represents
multiples of single nucleosomal repeat lengths of DNA
42
The location of the centromere within a chromosome is determined by
presence of histone variant CENP-A
43
Which of the following occupies the largest portion of the human genome?
intergenic
44
Condensation of chromatin requires ATP-hydrolyzing enzymes and __________to loop DNA and achieve a 10,000 fold packing ratio.
condensin complex
45
What statement is not true about plasmid DNA?
plasmid DNA is only found in bacteria
46
Which of the following is true of bacteriophage DNA packaging?
bacteriophages must back genome into a capsid
47
Histone proteins are the main architectural proteins found in bacteria.
t/f
false
48
Mitochondria contain DNA that encodes proteins important for oxidative phosphorylation.
t/f
true
49
Which of the following statements is correct?
DNA polymerase requires a primer to get started
50
Which of the following is NOT TRUE with regards to DNA replication?
DNA on lagging strand is continuous
51
Which of the following IS true with regards to DNA replication?
- DNA replication initiation begins at negatively supercoiled origin
- semiconservative
- origin is rich in A and T nucleotides
- normally bidirectional
52
Which of the following is an enzyme that would be found in Escherichia coli but not in humans?
DNA Pol I
53
What protein or protein complex binds to the origin of replication in E. coli cells to initiate DNA replication?
DnaA
54
When does DNA replication occur in a eukaryotic cell?
S phase
55
Eukaryotic chromosomal DNA typically has only one origin of replication
t/f
false
56
Eukaryotic chromosomal DNA replication occurs after replication licensing
t/f
true
57
Mammalian origins of replication do not have a consensus sequence
t/f
true
58
An origin of replication is a site on chromosomal DNA where a bidirectional pair of replication forks initiates.
t/f
true
59
Which enzyme is responsible for sealing the DNA backbone following primer removal?
DNA ligase
60
Which enzyme causes a double-strand DNA break while functioning?
topoisomerase II
61
Select all of the following that describe DNA transactions during replication.
- main enzyme for replication is DNA polymerase
- semidiscontinuous
- bidirectional with 2 replication forks
62
An induced mutation occurs
as a result of interaction of DNA with an outside agent
63
The most frequent UV light-induced DNA damage is
forming a thymine dimer
64
Which of the following is an intercalating agent?
ethidium bromide
65
Removal of DNA-protein cross-links will most likely occur using which of the following enzymes?
SPRTN protease
66
Which repair pathway would probably be involved in specifically recognizing and removing uracil (and other modified bases) from DNA?
base excision repair
67
The XP proteins are important for which type of repair?
nucleotide excision
68
DNA repair mechanisms exhibit a recurrent theme. Which of the following describes this theme accurately?
A nuclease cuts out the damage, a polymerase adds in the correct nucleotides, a ligase fills in the nick in the backbone.
69
Which type of repair uses DNA glycosylases?
base excision
70
The DNA repair system that removes replication errors and requires Mut proteins is
mismatch repair
71
Xeroderma pigmentosum may be caused by mutation in the gene that encodes DNA polymerase eta (η).
true
72
DNA polymerase eta (η) repairs DNA damage.
t/f
false
73
Transcription is defined as the production of a(n):
exact complementary strand of RNA from a DNA template.
74
Transcription begins at a ___________sequence encoded by the DNA when ____________recognizes the sequence.
promoter, RNA polymerase
75
What is the CORRECT order of transcriptional events that occurs during initiation?
Closed complex formation, open complex formation, abortive RNA synthesis, promoter clearance.
76
Which of the following sigma factors is essential for general transcription in exponentially growing E. coli cells?
sigma 70
77
Which of the following does NOT contribute to the efficiency with which E. coli RNA polymerase binds to a promoter?
sequence at the +10 region
78
Transcription terminates in E. coli when
termination sequences are reached leading to RNA hairpins
79
In E. coli, what is the function of the lac operon?
It ensures that a cell dedicates resources to the production of enzymes involved in lactose metabolism only when lactose is available in the environment.
80
In E.coli, what is the most likely thing to happen with the tryptophan operon when there are high levels of tryptophan?
transcription termination is likely
81
Which mode of action of a transcriptional regulator is exhibited by allolactose binding to the Lac repressor protein?
allosteric modification
82
Transcription and translation are coupled in bacteria.
t/f
true
83
Bacteria generally have introns that must be removed from a primary transcript.
t/f
false
84
Which of the following is trans acting?
transcription factor
85
Which of the following elements would most likely be closest in proximity to the transcriptional unit (coding sequence of a gene)?
TATA box
86
When the RNA Polymerase II initiates transcription in eukaryotes, which of the following are true
1. General transcription factors, designated TFIIB, TFIID, TFIIE, TFIIF, and TFIIH, are required.
2. TFIID is the first protein to bind the promoter.
3. TFIIA catalyzes the unwinding of the DNA helix
1 and 2
87
Which amino acid on a histone is post-translationally modified through acetylation?
lysine
88
What are transcription factors?
regulatory proteins that bind to specific DNA sequences
89
Which of the following is NOT a chromatin remodeling process?
nucleosome rushing
90
Which of the following IS a chromatin remodeling process?
- nucleosome remodeling
- nucleosome replacement
- nucleosome sliding
- nucleosome displacement
91
Which of the following is NOT a step in eukaryotic transcription initiation?
promoter termination
92
Which of the following IS a step in eukaryotic transcription initiation?
- pause release
- promoter melting
- abortive initiation
- promoter escape
93
Insulators are
long range regulatory elements
94
Hormones may play a role in gene expression by binding to receptors that act as transcription factors.
t/f
true
95
What is epigenetics?
Heritable change in gene expression that occurs without a change in the primary DNA sequence of an organism
96
Which of the following is a cause of epigenetic changes?
- aging
- infection
- behavior
- development
97
As a general rule, cytosine DNA methylation marks genes for
silencing
98
What are CpG islands associated with?
active promoters
99
Expression of single allele of a gene in a diploid organism based on the parent of origin is specifically called
genomic imprinting
100
Besides DNA methylation, what is a major mechanism of epigenetic control?
more than one answer is correct
histone modifications
phosphorylation of DNA polymerases
non-coding RNA
DNA acetylation
more than one answer is correct
101
Which of the following is a true difference between Class I and Class II transposable elements.
Class I includes SINEs and Class II includes Ac and Ds elements found in maize
102
The ovalbumin gene is much longer than the mRNA produced by this gene. What causes this discrepancy?
The introns have been removed during mRNA processing.
103
Which of the following is NOT a function of the 5' cap?
peroxisome targeting
104
Which of the following IS a function of the 5' cap?
- nuclear export
- protect mRNA
- facilitate loading onto small ribosomal subunit
- facilitate splicing
105
Which polymerase adds the 3' tail to a mRNA?
Poly(A) polymerase
106
siRNAs are processed by the enzyme ______. One strand of the siRNA is loaded into a silencing complex named _________. The siRNAs target mRNA for ___________.
dicer, RISC, mRNA degradation
107
The nuclear exosome
degrades aberrant mRNA's
108
RNA editing is a widespread mechanism for post-transcriptional modification of the base sequence of mRNA. In humans, RNA editing
occurs by deamination of adenosine to inosine, or cytidine to uridine
109
Which component is not directly involved in translation?
DNA
110
Which statement is not true about ribosomes:
peptide bond formation is catalyzed by a ribosomal protein
111
Which of the following steps comes last in translation initiation in eukaryotes?
joining of 40S and 60S subunit of 80S ribosome
112
Nascent polypeptides exit the ribosome via
long tunnel
113
Which of the following is not part of the ternary complex required for translation initiation?
mRNA
114
A ribosome translating a polypeptide that bears a signal sequence for targeting to the ER will bind to
signal recognition particle (SRP)
115
Peptidyl transferase activity in the ribosome transfers a growing polypeptide chain from a tRNA in the P site to an amino acid on a tRNA in the A site.
t/f
true
116
Release factors are tRNAs that are charged with selenocysteine and signal the end of translation.
t/f
false
117
In a single PCR cycle consisting of 30 seconds at 95°C, 1 min at 55°C, and 1 min at 72°C, what is happening in the step run at 55°C?
primers are annealing to the DNA to be amplified
118
Which of the following is an enzyme used in cloning that joins 2 DNA fragments by forming phosphodiester bonds?
DNA ligase
119
Given the following DNA sequence, which of the following would be a good set of primers to amplify the complete sequence (this sequence is shorter than we would actually use)?
5'ATCCTGTACTGGTCATTTCGTAAGGCTAC3'
5'ATCCT & 5'GTAGC
120
Which of the following best describes a key step in Illumina sequencing technology?
Fluorescently labeled nucleotides are incorporated one at a time, and the emitted signal is detected after each incorporation
121
What is a probe in molecular biology?
DNA or RNA molecule used in hybridization reactions
122
A researcher is studying gene expression and performs Southern, Northern, and Western blots on samples from the same tissue. Which of the following correctly matches each technique to its target molecule and the type of probe or detection used?
Southern blot – detects DNA using a labeled DNA or RNA probe;
Northern blot – detects RNA using a labeled nucleic acid probe;
Western blot – detects proteins using specific antibodies
123
A researcher is using gel electrophoresis to separate very small DNA fragments, less than 100bp in length. What type of gel should the researcher use to perform this separation?
polyacrylamide
124
RT-PCR is useful for:
- determining presence of specific mRNA
- determining transcription levels
- diagnosing covid-19
125
What is the genetic sequence of the template DNA sequenced using the Sanger method?
5' TTACAGTCGGAA 3'
complement of the strand presented, start reading from the top
126
In automated Sanger sequencing, what is the role of fluorescently labeled dideoxynucleotides (ddNTPs)?
allow detection and identification of terminating base at each position in the sequence
127
DNA typing by analyzing short tandem repeats has been used do all the following EXCEPT:
identify a newborn's risk of having cystic fibrosis
128
DNA typing can be used to do what?
- acquit accused murderer
- identify father of a child
- indentigy possible criminal using blood samples
129
The complete set of proteins present in a cell under a given set of conditions is a:
proteome
130
Mitochondrial DNA may be used in forensics instead of nuclear DNA because:
it is in higher copy number per cell
131
Which technique is commonly used to detect protein/DNA interactions?
Electrophoretic mobility shift assay (EMSA)
132
Using the STR profiles provided, who is most likely the father of the infant if the female is the mother?
male 3
133
Which of the following refers to the complete set of RNA transcripts produced by the genome of an organism under specific conditions or in a specific cell type?
transcriptome
134
Simultaneous amplification of many targets of interest in one reaction by using more than one pair of primers is achieved with
multiplex PCR
135
You are trying to determine if two proteins interact. Which of the following methods would be best to achieve your goal?
pull-down assay
136
Using a single short tandem repeat locus is sufficient to identify a person conclusively.
t/f
false
137
It is estimated that humans have 100,000 protein coding genes.
t/f
false
138
In the 1950s, Hershey and Chase conducted a now famous experiment to determine whether DNA or protein carried the hereditary information in bacteriophage T2. What method did they used to selectively label the DNA and protein components of bacteriophage T2?
35S to label the protein and 32P to label the DNA
139
Which nitrogenous base is this:
uracil
*not methylated like thymine
140
Hairpin loops, base-paired stems, and bulges make up what part of RNA's structure?
secondary
141
The term ribozyme describes what property of RNA molecules?
they are catalytic
142
The genetic code is said to be “degenerate” because
A single tRNA specific for a particular amino acid may respond to multiple codons in an mRNA
143
Which statement is not correct?
Question 10 options:
Eukaryotic chromosomal DNA replication occurs in "replication factories."
An origin of replication is a site on chromosomal DNA where a bidirectional pair of replication forks initiates.
Eukaryotic chromosomal DNA typically has only one origin of replication.
Origin DNA sequences usually have many A-T base pairs
Eukaryotic chromosomal DNA typically has only one origin of replication.
144
Telomerase is a ribonucleoprotein complex. The RNA component of the complex
provides the template for telomere repeat synthesis
145
A transversion mutation is one in which
one pyrimidine base is replaced with a purine base or vice versa
146
The disease xeroderma pigmentosum (XP) is a rare autosomal recessive condition in humans. Individuals with this condition are extremely sensitive to UV light and nucleotide excision repair activity is reduced. When cell cultures from normal individuals and from XP patients are irradiated with various doses of UV light and cultured in radiolabeled thymidine…
cells from XP patients incorporate significantly less radiolabeled thymidine into their DNA.
147
Which of the following statements is correct?
DNA polymerase requires a primer to get started.
RNA polymerase requires a primer to get started.
Both DNA and RNA polymerase require primers to get started.
Both DNA and RNA polymerase can start synthesis de novo.
DNA polymerase requires a primer to get started.
RNA polymerase functions de novo
148
DNA polymerase has a _______ error rate because it has _______________ mechanism.
low, proofreading
149
Full induction of the lac operon occurs when:
lactose levels are high and glucose levels are low
150
In the context of gene therapy, viruses are used as vectors.
This means that viruses
allow for transfer of foreign DNA molecules into a host cell.
151
Restriction fragment length polymorphism analysis with MstII is used to diagnose which of the following genetic diseases?
sickle cell anemia
152
Which of the following statements best describes the role of genes related to cancer development, including proto-oncogenes, tumor suppressor genes, and specific genes like p53
Proto-oncogenes can become oncogenes when mutated and promote uncontrolled cell growth; tumor suppressor genes like p53 normally inhibit cell division or promote apoptosis.
