Midterms practice test Flashcards by Tatiana Perez

If 20% of the nucleotides in an organism
are adenine, predict the percentage of
nucleotides that are guanine.
A. 20%
B. 30%
C. 40%
D. 60%

30%

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Which of the following is not required for
DNA replication by PCR?
A. Oligonucleotide primers
B. DNA polymerase
C. DNAligase
D. Deoxynucleotides

DNAligase

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A restriction enzyme recognizes the
sequence, 5’ CTAATAG 3’, and cuts as
indicated. Predict the ends that would
result on the complementary DNA strand.
A. 3’G5’ 3’ATATC5’
B. 3’GA5’ 3’TATC5’
C. 3’GATA5’ 3’TC5’
D. 3’GATAT5’ 3’C 5’

3’GATA5’ 3’TC5’

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The absorbance of a 1:100 dilution of
isolated dsDNA solution, measured at
260 nm, is 0.062. What is a reasonable
estimate for the dsDNA concentration
of the sample, expressed in ug/mL?
A. 3.1
B. 6.2
C. 310
D. 5000

310

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In the isolation of RNA, diethylpyrocarbonate (DEPC) is used to
A. Inhibit RNase
B. Lyse the cells
C. Precipitate the DNA
D. Remove buffer salts

Inhibit RNase

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The technique that makes ssDNA from
an RNA template is called
A. Strand displacement amplification
B. Polymerase chain reaction
C. Ligase chain reaction
D. Reverse transcription

Reverse transcription

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Purification resins used to isolate DNA
take advantage of the fact that DNA is
A. Double stranded
B. Negatively charged
C. Higher in concentration than RNA
D. Higher molecular weight than RNA

Negatively charged

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After performance of DNA electrophoresis, the isolated bands in the kilobase size
range appear too close together. Which of
the following can be done with the next
run to improve the appearance/separation
of the bands in the samples?
A. Increase the percent agarose concentration of the matrix
B. Increase the running time of the
electrophoresis assay
C. Increase the sample volume applied
to the gel
D. Decrease the sample volume applied
to the gel

Increase the running time of the
electrophoresis assay

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Which of the following is commonly used
as a label in molecular tests?
A. Biotin
B. DNase
C. RNase
D. 125I

Biotin

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Which of the following is not an example
of target amplification?
A. Reverse transcription-PCR (RT-PCR)
B. Transcription mediated amplification
(TMA)
C. Branched chain DNA amplification
(bDNA)
D. Polymerase chain reaction (PCR)

Branched chain DNA amplification
(bDNA)

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In forensic testing, DNA fingerprinting
can identify individuals with high
accuracy because
A. Human genes are highly conserved
B. Only a small amount of sample is
needed
C. Human gene loci are polymorphic
D. DNA is stable and not easily
contaminated

Human gene loci are polymorphic

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A 5850-base plasmid possesses EcoRl
restriction enzyme cleavage sites at the
following base pair locations: 36, 1652,
and 2702. Following plasmid digestion,
the sample is electrophoresed in a 2%
agarose gel. A DNA ladder marker,
labeled M in Color Plate 56B, is included
in the first lane, with base pair sizes
indicated in lanes A through D. Which
lane represents the sample pattern that is
most likely the digested plasmid?
A. A
B. B
C. C
D. D

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Which of the following is characteristic of
DNA chips (i.e., DNA microarrays)?
A. Allow detection and discrimination
of multiple genetic sequences at the
same time.
B. Thousands of oligonucleotide probes
are labeled and placed on glass or
silicon surfaces.
C. Unlabeled target sequences within the
patient sample are detected by
hybridization to labeled probes.
D. All the above

Allow detection and discrimination
of multiple genetic sequences at the
same time.

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The most useful feature of the molecules
streptavidin and biotin is that they bind
A. Specifically to nucleic acids
B. Only in neutral pH conditions
C. To each other with very high affinity
D. Directly to DNA immobilized on
nitrocellulose

Specifically to nucleic acids

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What is the theoretic estimation of the
number of DNA target sequences present
(per original double-stranded DNA in
solution) following 15 cycles of PCR?
A. 30
B. 210 (i.e., 1024)
C. 215 (i.e., 32,768)
D. 220 (i.e., 1,048,576)

215 (i.e., 32,768)

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“Star activity” for a restriction enzyme
refers to
A. An ability to cleave DNA at sequences
different from their defined recognition sites
B. The enzyme’s specificity for sites
of methylation within the nucleotide
sequence
C. The temperature and pH conditions
at which the enzyme will function
optimally
D. The percent increased accuracy of
the enzyme when placed in ideal
conditions of pH

An ability to cleave DNA at sequences
different from their defined recognition sites

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An ability to cleave DNA at sequences
different from their defined recognition sites

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If a DNA probe is added to nitrocellulose
after the transfer step but before the
blocking step, which of the following will
occur?
A. The probe will nonspecifically bind to
its DNA target.
B. Unoccupied spaces on the nitrocellulose will bind the probe.
C. The DNA target on the nitrocellulose
will be unable to bind the probe.
D. Bound probe will be washed away in
the next wash step.

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Which of the following items is not used
in the preparation of a DNA probe for
Southern blotting using random hexamer
primers?
A. Template DNA
B. Three unlabeled deoxynucleotides
C. Dideoxynucleotides, with one of them
labeled
D. DNA polymerase

Dideoxynucleotides, with one of them
labeled

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Which of the following is considered a
“high stringency” condition for DNA
probe protocols?
A. Using wash buffer with highly acidic
pH
B. Washing the matrix with high-salt
buffer
C. Radiolabeling the probe with 35S
rather than 32P
D. Washing the transfer membrane
(e.g., nitrocellulose or nylon) at high
temperature

Washing the transfer membrane
(e.g., nitrocellulose or nylon) at high
temperature

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When compared to Southern blot
hybridization testing, PCR
A. Is less sensitive to DNA degradation
than Southern blot
B. Includes transfer of DNA onto a nylon
membrane
C. Requires no specialized equipment
D. Is more labor intensive

Is less sensitive to DNA degradation
than Southern blot

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What enzyme recognizes and cuts
overlapping DNA sequences formed
between mutant or normal probes and
target sequences within samples?
A. Restriction endonuclease
B. DNAligase
C. Cleavase
D. RNaseH

Cleavase

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Which of the following specimen types is
not used routinely as source material for
molecular genetic tests?
A. Whole blood
B. Buccal scrapings
C. Amniocytes
D. Rectal swabs

Rectal swabs

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TaqMan probes used to increase specificity of real-time PCR assays generate a
fluorescent signal
A. At the beginning of each cycle during
the denaturation step
B. When the probes bind to the template
(i.e., during annealing)
C. When the probe is digested by 5’ —> 3’
exonuclease activity during extension
of primers (i.e., DNA synthesis)
D. When the reporter fluorophor on the
probe is separated from the quencher
molecule by a restriction enzyme

When the probe is digested by 5’ —> 3’
exonuclease activity during extension
of primers (i.e., DNA synthesis)

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For the purpose of diagnosing genetic diseases, what component of whole blood is used for the extraction of DNA? A. Leukocytes B. Plasma C. Platelets D. Red blood cells

Leukocytes

Which of the following statements best describes characteristics of RNase? A. It degrades mRNA but not rRNA. B. It is found in large concentrations on hands. C. Its activity can be eliminated by autoclaving. D. Its activity occurs in a limited temperature range between 25 and 65°C.

It is found in large concentrations on hands.

Which of the following is the least likely inhibitor of PCR? A. Heme B. Sodium heparin C. DEPC (diethylpyrocarbonate) D. EDTA (ethylenediaminetetraacetic acid)

EDTA (ethylenediaminetetraacetic acid)

Frequently, DNA probes are used to detect target sequences in Northern or Southern blots. Hybridization occurs between DNA probe and RNA or DNA on the blot, respectively. To ensure that only exactly matched complementary sequences have bound together, the blot is washed under stringent conditions. Stringency of the wash steps to remove unbound and mismatched probe can be increased by A. High temperature, high NaCl concentration, and high detergent (i.e., SDS) solution B. High temperature, low NaCl concentration, and high detergent (i.e., SDS) solution C. High temperature, high NaCl concentration, and low detergent (i.e., SDS) solution D. Low temperature, high NaCl concentration, and high detergent (i.e., SDS) solution

High temperature, low NaCl concentration, and high detergent (i.e., SDS) solution

In RNA, which nucleotide base replaces thymineofDNA? A. Adenine B. Cytosine C. Guanine D. Uracil

Uracil

The component parts of a dNTP include a purine or pyrimidine base, a A. Ribose sugar, and one phosphate group B. Deoxyribose sugar, and three phosphate groups C. Ribose sugar, and two phosphate groups D. Deoxyribose sugar, and two phosphate groups

Deoxyribose sugar, and three phosphate groups

Molecular typing of bacterial strains is based on restriction fragment length polymorphisms (RFLPs) produced by digesting bacterial chromosomal DNA with restriction endonucleases. Which of the following techniques is used to separate the large DNA fragments generated? A. Ribotyping B. DNA sequencing C. Pulsed field gel electrophoresis D. Reverse transcription-polymerase chain reaction

Pulsed field gel electrophoresis

Which of the following amplification methods does not employ isothermal conditions? A. Nucleic acid sequence-based amplification (NASBA) B. Polymerase chain reaction (PCR) C. Strand displacement amplification (SDA) D. Transcription mediated amplification (TMA)

Polymerase chain reaction (PCR)

The coding region of a human gene is called A. Exon B. Intron C. SNP D. VNTR

Exon

The central dogma is that DNA is used to make RNA, which is then used to make protein. In this scheme the two processes that are involved (i.e., DNA to RNA and RNA to protein) are termed A. Replication and transcription B. Synthesis and encryption C. Transcription and translation D. Initiation and elongation

Transcription and translation

How many chromosomes are contained in a normal human somatic cell? A. 22 B. 23 C. 44 D. 46

An ordered sequence of events makes up the cell cycle. Which of the following describes the correct sequence of events starting at Gl? A. G1,G2, S,M B. G1,S,G2,M C. G1,M,G2, S D. G1,S,M, G2

G1,S,G2,M

Purified DNA remains stable indefinitely when stored as A. Small aliquots at 4°C B. Large aliquots at 25°C C. Small aliquots at -70°C D. Large aliquots at -20°C

Small aliquots at -70°C

An advantage of amplification technologies for clinical laboratories is that A. They require inexpensive test reagents B. They lend themselves to automated methods C. Each target molecule sought requires a unique set of primers D. Contamination is not a concern when performing these assays

They lend themselves to automated methods

The assay method that detects the expression of a gene rather than the mere presence or structure of a gene is termed A. RT-PCR B. TMA C. Multiplex PCR D. Ribotyping

RT-PCR

Which of the following assays cannot be accomplished using PCR methods employing only Tag polymerase? A. Diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae infection B. Detection of single base pair gene mutations, such as in cystic fibrosis C. Detection of HLA-A, B and DR genotypes D. Determination of viral load for HCV

Determination of viral load for HCV

One method to prevent "false-positive" PCR results includes the use of dUTP in the reaction mix, resulting in amplicons containing U in place of T. The enzyme used to decrease contamination is A. Uracil-/V-glycosylase B. Tag polymerase C. SI nuclease D. DNase

Uracil-/V-glycosylase

Which double-stranded DNA molecule has the highest melting temperature? A. An oligonucleotide with a repeating sequence of A-A-A at the 5´ end B. A molecule of 5,000 base pairs with a high number of A-T base pairs C. An oligonucleotide with a large number of repeating C-G-C codons D. A DNA polymer of 100,000 base pairs

An oligonucleotide with a large number of repeating C-G-C codons

Which base pair sequence is most likely to serve as a binding site for a restriction endonuclease? A. A-T-T-C-A T-A-A-G-T B. C-T-A-C-T-G G-A-T-G-A-C C. C-A-C G-T-G D. A-A-G-C-T-T T-T-C-G-A-A

A-A-G-C-T-T T-T-C-G-A-A

Cloning a human gene into a bacterium in order to make a large molecular probe requires which vector? A. Plasmid B. Bacterial microsome C. 30S bacterial ribosome D. Single-stranded DNA

Plasmid

What process can be used to make a DNA probe produce a fluorescent or chemiluminescent signal? A. Enzymatic attachment of acridinium esters to terminal ends of the probe B. Substitution of biotinylated or fluorescent nucleotides into the probe C. Splicing the gene for β-galactosidase into the probe D. Heat denaturation of the probe followed by acid treatment

Substitution of biotinylated or fluorescent nucleotides into the probe

What term describes the products produced when DNA is digested by restriction endonucleases? A. Mosaicisms B. Chimeras C. Amplicons D. Restriction fragment length polymorphisms

Restriction fragment length polymorphisms

What reagent is most commonly used to stain DNA separated by electrophoresis? A. Silver nitrate B. Nicotinamide adenine dinucleotide C. Cationic dye D. Ethidium bromide

Ethidium bromide

Which technique is used to detect DNA containing a specific base sequence by applying a labeled probe to DNA bands immobilized onto nitrocellulose paper following electrophoresis? A. Southern blot B. Northern blot C. Dot blot D. Western blot

Southern blot

Which of the following types of mutation causes the premature termination of protein synthesis? A. Missense B. Nonsense C. Insertion D. Frame shift

Nonsense

In humans, which component of a gene is translated into a protein? A. Intron B. Exon C. Promoter D. TATA box

Exon

Which statement best describes a DNA polymorphism? A. A point mutation arising in a gene B. Any change in DNA that is associated with abnormal function C. A change in the base sequence of DNA that is translated into an abnormal protein D. A variation in DNA that occurs with a frequency of at least 1%

A variation in DNA that occurs with a frequency of at least 1%

Which of the following is the most common type of polymorphism? A. Single nucleotide polymorphism (SNP) B. Variable number tandem repeat (VNTR) C. Short tandem repeat (STR) D. Short repetitive interspersed element (SINES)

Single nucleotide polymorphism (SNP)

Which of the following mechanisms facilitates DNA separation by capillary electrophoresis? A. Molecular sieving B. Partitioning C. Adsorption D. Deflection

Molecular sieving

The polymerase chain reaction (PCR) involves three processes. Select the order in which these occur. A. Extension→Annealing→Denaturation B. Annealing→Denaturation→Extension C. Denaturation→Annealing→Extension D. Denaturation→Extension→Annealing

Denaturation→Annealing→Extension

In the PCR cycle, how is denaturation accomplished? A. Heat B. Alkali treatment C. Addition of sulfonylurea D. Formamide

Heat

What is the composition of the primer used in PCR? A. A cocktail of enzymes and nucleotide triphosphates that bind to the target B. An oligonucleotide complementary to bases at the 3´ end of the target C. A small piece of dsDNA that attaches to the template D. A probe made of mRNA that binds downstream from the target

An oligonucleotide complementary to bases at the 3´ end of the target

The master mix solution used for PCR contains which of the following reagents? A. Deoxyribonucleotide triphosphates B. Deoxyribonucleotide monophosphates C. Deoxyribonucleosides D. Ribonucleotide monophosphates

Deoxyribonucleotide triphosphates

What is the unique characteristic of the DNA polymerase, Taq DNA polymerase, used in PCR? A. It can be enzyme labeled B. It is more efficient than eukaryotic polymerases C. It is heat stable D. It works with DNA of any species

it is heat stable

In PCR methods, how can several targets be copied simultaneously and detected? A. By following the increase in absorbance at 260 nm during melting B. By labeling multiple primers with specific fluors C. By substitution of hybridization probes for primers D. By analysis of adenosine tail signatures

By labeling multiple primers with specific fluors

Which formula predicts the number of PCR products that can be produced? A. 2n where n is the number of cycles B. N4 where N is the number of cycles C. p2 + 2pq + q2 = 1 where p and q are the number of primers D. N2/2 where N is the number of cycles

2n where n is the number of cycles

How can PCR be applied to the detection of human immunodeficiency and other RNA viruses? A. The virus must be inserted into human DNA by viral integrase prior to PCR B. Substitute deoxyuridine triphosphate in place of deoxythymidine triphosphate in the master mix C. Add a heat-stable reverse transcriptase enzyme to the master mix D. Substitute ribonucleotide triphosphates for deoxyribonucleotide triphosphates in the master mix

Add a heat-stable reverse transcriptase enzyme to the master mix

Which statement best describes the method of branched DNA signal amplification? A. The DNA template is amplified directly using patented enzymes B. Multiple primers are used to create branches of the template DNA, permitting multiple extension sites C. The target DNA is denatured and hybridized to RNA, and the hybrid molecules are amplified by both DNA and RNA polymerases D. The target DNA is bound by multiple probes, and those are amplified instead of the target DNA

The target DNA is bound by multiple probes, and those are amplified instead of the target DNA

A PCR reaction is performed, and the negative control demonstrates the presence of a detectable number of PCR products (amplicons) by capillary electrophoresis. What is the most likely cause? A. False-positive post-PCR hybridization reaction due to low stringency B. Dimerization of PCR primers C. Contamination of control sample with a trace amount of template DNA D. Background signal from gel fluorescence or inadequate removal of unbound probe

Contamination of control sample with a trace amount of template DNA

How can a false-negative PCR test caused by the presence of an inhibitor of the reaction in a patient’s sample be detected? A. Using a positive control B. Using an internal control C. Performing each test in duplicate D. Performing serial dilutions of the sample

Using an internal control

All of the following are requirements for reducing contamination in DNA amplification methods except: A. Use of aerosol barrier pipette tips when transferring samples or reaction products B. Preparation of reagents in a dead air box or biological cabinet C. A separate area for performing preamplification, postamplification, and detection steps D. Pretreatment of samples with high-intensity ultraviolet light

Pretreatment of samples with high-intensity ultraviolet light

How are PCR methods adapted to yield quantitative data? A. By comparing PCR product to an internal standard B. By applying a conversion factor to the PCR signal that converts it to copies per milliliter C. By determining the mass of PCR product using ultraviolet spectrophotometry D. By making serial dilutions of the sample

By comparing PCR product to an internal standard

A PCR analysis of a vaginal sample for Chlamydia trachomatis gives a negative result (optical density of biotinylated reaction product below the cutoff point). The internal control result is also below the cutoff. Positive and negative controls produced acceptable results. What action should be taken? A. The test should be reported as negative B. The sample should be diluted and the test repeated C. The result should not be reported and the sample should be repeated D. A preliminary result of negative should be reported but should be confirmed by further testing using a different method of analysis

The result should not be reported and the sample should be repeated

In real-time PCR analysis, the absolute concentration of PCR product is determined by plotting which two values? A. Fluorescent intensity versus melting temperature B. The threshold cycle versus concentration C. The well factor versus threshold cycle D. The melting temperature versus concentration

The threshold cycle versus concentration

In real-time PCR, quantitation can be done without standards of known copy number. Relative quantitation (estimated concentration) is possible because: A. Each cycle generates a twofold increase in product B. Each cycle threshold represents a 10-fold increase in product C. The fluorescence of two samples can be compared directly D. Concentration is proportional to fluorescence at the endpoint of the PCR reaction

Each cycle generates a twofold increase in product

Which real-time PCR parameter can be used to detect the presence of a contaminant? A. Threshold cycle B. Baseline C. Melting temperature D. Relative fluorescent intensity

Melting temperature

In real-time PCR, what value is needed in order to determine the threshold? A. Background signal B. Melting temperature C. Maximum fluorescence D. Threshold cycle

Background signal

In real-time PCR, which of the following methods is not based on using a probe? A. TaqMan B. Molecular beacon C. Scorpion D. SYBR green

SYBR green

Which statement accurately describes the process of fluorescent in situ hybridization (FISH)? A. Hybridization is performed on DNA extracted from cells B. Hybridization is performed directly on intact chromosomes C. Hybridization probes are attached to histones associated with the chromosomes D. Hybridization occurs by attachment to the probe only at the centromere

Hybridization is performed directly on intact chromosomes

Which type of specimen would be unsuitable for FISH analysis? A. Paraffin-embedded tissue B. Cells with chromosomes in metaphase C. Cells with chromosomes in interphase D. A cell suspension containing maternal and fetal blood

A cell suspension containing maternal and fetal blood

FISH can distinguish each of the following chromosomal abnormalities except: A. Aneuploidy B. Translocation C. Deletion D. Trinucleotide repeats

Trinucleotide repeats

In microarray and macroarray analysis, which molecules are labeled? A. The immobilized DNA molecules B. The sample DNA C. Both target and sample molecules D. The substrate matrix

The sample DNA

How can all of the mRNA within a sample be amplified to prepare microarray probes? A. A specific primer for each mRNA must be synthesized B. A primer is made to the polyA tail of mRNA C. Nonspecific attachment of T7 polymerase occurs when the cells are treated with detergent D. Random primer sets are used under low stringency conditions

A primer is made to the polyA tail of mRNA

What is the difference between a microarray and a macroarray DNA assay? A. The number of targets is larger on a macroarray B. The molecular size of each target is larger on a macroarray C. The amount of each target is larger on a macroarray D. The substrate used for a macroarray is different from a microarray

he amount of each target is larger on a macroarray

Protein microarray analysis requires the use of which of the following techniques to generate protein profile data? A. Electrophoresis B. Mass spectroscopy C. Thin-layer chromatography D. Gas chromatography

Mass spectroscopy

In the reverse transcriptase PCR, the cDNA is synthesized by: a. reverse transcriptase b. DNA polymerase c. Oligo dT primers d. RNAse H

reverse transcriptase

disadvantages of using a nested PCR

susceptible to contamination

What is the relationship of the fluorescent dye to the single stranded DNA in every PCR cycle? a. direct relationship b. inverse relationship c. no relationship d. none of these options

no relationship

What will happen to the target DNA sequence if the annealing temperature is too high? 1. No hybridization takes place 2. Primers and templates remains dissociated 3. Production of mismatch hybrids 4. Amplification is more likely to occur at nontarget sites in the template molecule a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 2 and 4 e. 1 and 4

1 and 2

What will happen to the target DNA sequence if the annealing temperature is too low? 1. No hybridization takes place 2. Primers and templates remains dissociated 3. Production of mismatch hybrids 4. Amplification is more likely to occur at nontarget sites in the template molecule a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 2 and 4 e. 1 and 4

3 and 4

What would be the effect to the amplicons, if the denaturation temperature is too low?

the DNA will not completely denature and amplification efficiency will be low

Which of the following are correct when using a Multiplex PCR? 1. A minimum of three primer sets designed for amplification of different targets are included in the same PCR reaction. 2. More than one target sequence in a clinical specimen can be amplified in a single tube. 3. The primers used must be selected carefully to have similar annealing temperatures should be complementary to each other. 4. The amplicon sizes should be different enough to form distinct bands when visualized by gel electrophoresis. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 2 and 4

2 and 4 Multiplex PCR facts: More than one target sequence in a clinical specimen can be amplified in a single tube. The amplicon sizes should be different enough to form distinct bands when visualized by gel electrophoresis. A minimum of one primer sets designed for amplification of different targets are included in the same PCR reaction. The primers used must be selected carefully to have similar annealing temperatures but should not be complementary to each other.

Which of the following is true about the length of a primer:

If the primers are too short, they might hybridize to nontarget sites and give undesired amplification products

Which of the following troubleshooting procedures must be performed when the annealing time is too short?

use an annealing time of at least 30 seconds

result if Too few cycles were used

Can lead insufficient amplification

result if Extension time is too short

incomplete replication of the target

result if Annealing times too short

Primers do not have enough time to bind to the template

Annealing temperature was too high

Primers are unable to bind to the template

Denaturation temperature was too low

incompletely denature and amplification efficiency will be low

Denaturation time was too long

DNA might be degraded

Denaturation time was too short

incompletely denature and amplification efficiency will be low

TRUE OR FALSE To use a more cycles when the temperature concentration was high and used less cycles when the temperature concentration was low

False; they are inversely proportional

TRUE OR FALSE Rule of thumb (Annealing Temperature) should be 5 C lower than the melting point of primer

TRUE

Implies that data collection and analysis occur in a reaction proceeds

Real Time

true or false Annealing temperature is independent on the primers sequences and is the critical factor for a successful PCR reaction.

False; it is dependent

1 Statement is true, 2 Statement is true

Statement 1- If the primers are too short, they might hybridize to nontarget sites and give undesired amplification products. Statement 2 - Long primers hybridize at a slower rate. The efficiency of the PCR is therefore reduced if the primers are too long A. Neither Statements are correct B. 1 Statement is true, 2 Statement is true C. 1 Statement is false, 2 Statement is true D. 2 Statement is false, 1 Statement is true

1 Statement is true, 2 Statement is true

Statement 1:Nested PCR was developed to increase the sensitivity but has a low specificity of PCR Statement 2: The products of the first round of amplification are then subjected to a second round of amplification using the first set of primers A. Neither Statements are correct B. 1 Statement is true, 2 Statement is true C. 1 Statement is false, 2 Statement is true D. 2 Statement is false, 1 Statement is true

1 Statement is false, 2 Statement is true rationale: Nested PCR was developed to increase the sensitivity and specificity of PCR

All are true about the multiplex PCR , except a. more than one target sequence in a clinical specimen can be amplified in a single tube. b. The primers used in multiplex reactions must be selected carefully to have similar annealing temperatures and must be complementary to each other. c. The amplicon sizes should be different enough to form distinct bands when visualized by gel electrophoresis d. None of the above

The primers used in multiplex reactions must be selected carefully to have similar annealing temperatures and must be complementary to each other. Rationale: must not be complementary to each other.

Statement 1 - A reaction’s Ct is directly linked to the starting concentration of target sequence Statement 2 - In the linear part of the PCR amplification, the Ct is directly correlated with the log of the number of nucleic acid target sequence copies initially present in the sample A. Neither Statements are correct B. 1 Statement is true, 2 Statement is true C. 1 Statement is false, 2 Statement is true D. 2 Statement is false, 1 Statement is true

2 Statement is false, 1 Statement is true rationale: In the linear part of the PCR amplification, the Ct is inversely correlated with the log of the number of nucleic acid target sequence copies initially present in the sample

Uses two pairs of amplification and two rounds of PCR a. multiplex PCR b. RT PCR c. Nested PCR d. Digital PCR

Nested PCR

Statement 1 - Random hexamers/decamers are 18-base long long single stranded oligonucleotides of random sequences Statement 2 - Oligo dT primers are 12-base long single stranded poly dT sequence that will prime cDNA synthesis from mRNA with poly A tails A. Neither Statements are correct B. 1 Statement is true, 2 Statement is true C. 1 Statement is false, 2 Statement is true D. 2 Statement is false, 1 Statement is true

Neither Statements are correct Rationale: Random hexamers/decamers 6 to 10 long base Oligo dT primers are 18-base long

Primers in RT PCR

Oligo dT and random hexamers/decamers

Statement 1: Denaturation: occurs for 20-30 seconds at 94 degrees Celsius. Statement 2: Annealing: occurs for 20-30 seconds at 50-60 degrees Celsius Statement 3:Elongation: typically run at 72-74 degrees Celsius for 5 to 15 minutes A. Neither Statements are correct B. 1 and 2 Statement is true, 3 Statement is false C. 1 Statement is false, 2 and 3 Statement is true D. 2 Statement is false, 1 and 3 Statement is true E. All statements are true

2 Statement is false, 1 and 3 Statement is true rationale:Annealing: occurs for 20-40 seconds at 50-60 degrees Celsius

True or false During the elongation step, the DNA polymerase will synthesize new double stranded DNA.

TRUE

Choose A – 1st false 2nd true Choose B 1st true 2nd false Choose C both false Choose D both true In qPCR, regardless of starting point, all reactions will end at the same, or similar, concentration. qPCR involves gathering of information during the reaction, when different reactions are still in the exponential phase.

Choose A – 1st false 2nd true Choose B 1st true 2nd false Choose C both false Choose D both true Cycle threshold is the number of PCR cycles required to exceed the background fluorescence. It is also the number of which the fluorescence of the given sample crosses the threshold value

The conventional PCR can only evaluate the end product of PCR reaction, which can be quantitatively but not qualitatively accurate. The qPCR eliminates the need for post amplification manipulation. Choose A – 1st false 2nd true Choose B 1st true 2nd false Choose C both false Choose D both true

If the denaturation time is too short, the DNA will completely denature and amplification efficiency will be low. For the initial denaturation, use 3 min to activate the polymerase and to denature the template during cycling, use 30 sec. Choose A – 1st false 2nd true Choose B 1st true 2nd false Choose C both false Choose D both true

If the annealing temperature is too high, primers are unable to bind to the template. The rule of thumb is to use an annealing temperature that is 5°C higher than the melting point of the primer. Choose A – 1st false 2nd true Choose B 1st true 2nd false Choose C both false Choose D both true

Which generation of sequencing relied on cycles of the termination of DNA polymerization and recording of the incorporated nucleotides in each cycle? a. Manual sequencing b. Third generation sequencing c. Second generation sequencing d. None of these e. First generation sequencing

Production of a human protein in bacteria genetic engineering is possible because: a. Bacterial cell can carry out the RNA splicing reactions b. The genetic code is universal c. The mechanism of gene regulation is identical in human and bacteria d. The human chromosome can replicate in bacterial cell

For protein detection, the most commonly used probe is?

Antibody

1st statement: Chain-termination DNA sequencing is based on the principle that during DNA synthesis, addition of a nucleotide triphosphate requires a free hydroxyl group on the 3’ carbon of the sugar of the first nucleotide of the growing DNA strand. 2nd statement: However, if a synthetic dideoxynucleotide that lacks a hydroxyl group at the 5’ carbon of the sugar moiety is incorporated at the end of the growing chain, DNA synthesis stops because a phosphodiester bond cannot be formed with the next incoming nucleotide. a. Only the second statement is true b. Both statements are true c. Only the first statement is true d. Both statements are false

A technique of centrifugation that uses repeated centrifugation with a progressive speed that will fractionate the cell homogenates into their components.

differential centrifugation

All are the example criteria for selecting a technique for protein quantification and purification, EXCEPT:

Storage temperature

the process by which a sample is broken into identical parts so that removing one portion of it does not disrupt and still accurately reflects the remaining sample's molecular composition.

Homogenization

The technique used to detect the presence of DNA or RNA in a Non-fractionated DNA sample is?

Dot Blot Technique

Which of the following cell lysis detergent are not example of non-ionic type detergent? a. Tween 80 b. Triton X-100 c. NP-40 d. Tween 20 e. Sodium dodecyl sulfate

Before DNA sequencing, the template DNA must first be prepared by ensuring that there is enough single-stranded version of the DNA to be used. Which among the following is not used to prepare the template DNA?

Phage vector B7

The most widely used device to separate a homogenate into different parts or fractions.

Centrifugation

The principle techniques to remove contaminants and detergent from proteomic samples use saturated salts to precipitate proteins in the form of ammonium sulfate precipitation or sodium sulfate.

Salting out

was the first of the high-throughput DNA sequencing technologies to be made commercially available.

pyrosequencing

1st statement: Because the Klenow polymerase has low processivity, it can only synthesize a relatively short DNA strand before dissociating from the template. This limits the length of sequence that can be obtained from a single experiment to about 250 bp. 2nd statement: To improve this short synthesis problem, most sequencing today makes use of a more specialized enzyme, such as Sequenase which is a modified version of the DNA polymerase encoded by bacteriophage T5. Sequenase has high processivity and no exonuclease activity and so is ideal for chain-termination sequencing, enabling sequences of up to 750bp to be obtained in a single experiment. a. Only the second statement is true b. Both statements are true c. Only the first statement is true d. Both statements are false

Which among the following is not a method of how manual sequencing was automated. a) replacement of radioactive labels by fluorescent labels b) use of thermal cyclers c) use of fluorescent detection systems, d) use of capillary gel electrophoresis e) none of these

Which of the following substances/chemicals will not interfere with the Lowry colorimetric method?

Tris buffer

What is the color reaction of Bicinchonic acid assay?

Deep-blue reaction

What is the chemical reactant used in Bradford assay?

Deep-blue reaction

What is the chemical reactant used in Bradford assay?

Coomassie brilliant blue

The principle of this colorimetric assay is based on the complex formation of cupric ions with the proteins.

Biuret reaction

This type of buffer for 2DE disrupts the non-covalent and ionic bonds between amino acid residues

Chaotropic agents

What is the difference between the Urea-PAGE and SDS-PAGE?

Urea-PAGE Denature RNA strands, while the SDS-PAGE denature proteins and coat with them in negative charges.

This device is used for identification of each protein in the sample which undergo digestion, ionization and fragmentation.

Mass spectrometry