Exam 3 Flashcards
A mutation changes a codon to another codon that does not change the original amino acid to a different amino acid. This is a
a. silent mutation
b. missense mutation
c. nonsense mutation
d. frameshift mutation
a. silent mutation
Which of the following is an example of a somatic mutation?
a. A mutation in an embryonic muscle cell
b. A mutation in a sperm cell
c. A mutation in an adult nerve cell
d. Both a and c
d. Both a and c
Which of the following is a cause of spontaneous mutations?
a. 5-bromouracil used for chemotherapy
b. UV light
c. A tautomeric shift that causees mis-base pairing
d. A chemical such as nitrous acid that can change the structure of a base
c. A tautomeric shift that causes mis-base pairing
A key event that promotes trinucleotide repeat expansion is
a. chromosome breakage
b. the presence of an AT-rich region
c. the presence of a lesion in the DNA
d. the formation of a hairpin
d. the formation of a hairpin
Which of the following is/are possible reason why a mutation may have a positive effect?
a. The mutation is located next to the gene’s promoter
b. The mutation is a translocation that moves the gene from a euchromatic region to a heterochromatic region
c. The mutation is an inversion that moves a gene’s promoter next to the regulatory sequences of a different gene
d. Both b and c
d. Both b and c
Let’s suppose that a chemical is a mutagen. If you tested this chemical using the Ames test, there would be ____ colonies on the plates in which the cells had been exposed to the mutagen, because the mutagen converts some of the cells from ____.
a. less, his+ to his-
b. more, his+ to his-
c. less, his- to his+
d. more, his- to his+
d. more, his- to his+
Below are 4 steps that occur in the nucleotide excision repair system. What is their correct order?
A. Removal of the damaged region
B. Endonuclease cleavage on either side of the lesion
C. Sensing of a DNA lesion
D. Use of the opposite strand (without a lesion) as a template to make new DNA
C, B, A, D
Gene conversion may occur via
a. mismatch repair
b. gap repair synthesis
c. nucleotide excision repair
d. both a and b
d. both a and b
According to the Holliday model for homologous recombination, a heteroduplex is formed due to
a. the initial breakage of the DNA at a single location in two different DNA strands
b. the formation of a D loop
c. the migration of a Holliday junction
d. the resolution of the Holliday junction into two separate DNA molecules
c. the migration of a Holliday junction
According to the Holliday model for homologous recombination, what is/are the possible end result(s) of the resolution step?
a. Recombinant chromosomes without a heteroduplex region
b. Recombinant chromosomes with a heteroduplex region
c. Nonrecombinant chromosomes with a heteroduplex region
d. Both b and c are possible
d. Both b and c are possible
The restriction enzymes shown below cut DNA in the following manner. The slashes indicate where cutting occurs.
BamHI G\GATCC
CCTAG\G
EcoRI G\AATTC
CTTAA\G
HaeII GGCGC\C
C\CGCGG
PstI CTGCA\G
G\ACGTC
Which of these enzymes would generate sticky ends that would be the most stable when they bind to complementary sticky ends?
a. BamHI
b. HaeII
c. EcoRI
d. PstI
b. HaeII
Which of the following steps is not needed to make a cDNA (complementary DNA library)?
a. Attach linkers to the cDNA
b. Cut cDNA and vector with a restriction enzyme, and ligate the cDNA into the vector
c. Isolate chromosomal DNA and digest with a restriction enzyme
d. Isolate mRNA and make cDNA using reverse transcriptase and a poly-dT primer
c. Isolate chromosomal DNA and digest with a restriction enzyme
During PCR, what is the order of events in a single cycle?
a. Annealing of the primers, denaturation of the DNA, synthesis of complementary strands
b. Annealing of the primers, synthesis of complementary strands, denaturation of the DNA
c. Denaturation of the DNA, synthesis of complementary strands, annealing of the primers
d. Denaturation of the DNA, annealing of the primers, synthesis of complementary strands
d. Denaturation of the DNA, annealing of the primers, synthesis of complementary strands
During real-time PCR, why does the level of fluorescence given off by the TaqMan probe decrease over time?
a. Reverse transcriptase cleaves the TaqMan probe, which separates the quencher and the reporter
b. Taq polymerase cleaves the TaqMan probe, which separates the quencher and the reporter
c. Taq polymerase binds to the TaqMan probe and causes its fluorescence to increase
d. As the PCR products accumulate, the Taqman probe binds to more template strands and thereby gives off more fluorescence
b. Taq polymerase cleaves the TaqMan probe, which separates the quencher and the reporter
A primer used in dideoxy DNA sequencing is 20 nucleotides long and has the following sequence: 5’-GGATCCATGACTAGTCCGAC-3’. A segment of DNA is cloned into a vector and then the vector DNA is denatured and subjected to dideoxy DNA sequencing method. Below is the DNA sequence from a region of the vector. The primer-annealing site is shown in bold and underlined.
3-CCCGATCGGCCTAGGTACTGATCAGGCTGAATGACT-5’
Based on the sequence above, what would be the size(s) of the band(s) (i.e., the number of nucleotides in each band) in which dideoxyT had been added to the sequencing reaction?
a. 1, 2, and 5
b. 21, 22, and 25
c. 3 and 7
d. 23 and 27
b. 21, 22, and 25
Researchers conducted Northern blotting on a sample of cells from mouse kidney, brain, and liver using a probe that is complementary to a gene that encodes a glucose transporter. All of the samples were taken from the same mouse. The following results were obtained:
(shows kidney smaller strand than brain and liver)
If we assume that equal amounts of total cellular RNA was loaded into each lane, which of the following statements is true?
a. Brain cells express this gene at the highest level
b. The pre-mRNA is alternatively spliced
c. The gene in the kidney cells has suffered a deletion
d. All of the above are false
b. The pre-mRNA is alternatively spliced
Which component of the CRISPR-Cas system causes it to bind to a target gene?
a. Cas9 protein
b. Spacer region of sgRNA
c. TracrRNA region of the sgRNA
d. Linker region of the sgRNA
b. Spacer region of the sgRNA
Glofish are zebrafish that contain a gene from either a coral or jellyfish. This is an example of
a. gene replacement
b. gene addition
c. a gene knockout
d. both a and b
b. gene addition
Reproductive cloning is a method of using the genetic material from somatic cells to produce offspring that are genetically identical to the donor parent. How does this approach work?
a. A somatic cell, such as a mammary cell, is made totipotent by treating it with hormones
b. A somatic cell, such as a mammary cell, has its nucleus removed and then the nucleus from an oocyte is inserted into it
c. A somatic cell, such as a mammary cell, is fused with an egg cell that had its nucleus removed
d. A sperm and egg cell are fused with a somatic cell (e.g., a mammary cell) that had its nucleus removed
c. A somatic cell, such as a mammary cell, is fused with an egg cell that had its nucleus removed
One method of molecular pharming involves the synthesis of human proteins into the milk of cows. As an example, let’s consider the production of human antibodies in cow’s milk. Which of the following components would not be needed to achieve this goal?
a. Coding sequence of a human antibody gene
b. Beta-lactoglobulin promoter from a cow
c. Enhancer sequences from a human antibody gene
d. Cow oocyte
c. Enhancer sequences from a human antibody gene