This document provides a multiple choice quiz on basic laboratory techniques related to blotting. It contains 33 questions testing understanding of techniques like Southern blotting, which is used to analyze the compositional properties of DNA, and transfers DNA from agarose gels to membranes. The questions cover topics like the purpose of blotting, what membranes are used, how large DNA fragments require longer transfer times, and what probes are commonly used in Southern blotting.

1. MCQs focuses on “Basic Laboratory Techniques – 3”
Author: Dr. R. N. Chavhan, Department of Zoology, RMG College, Nagbhid
1. What is used to transfer nucleic acid from gels to membranes for further analysis?
a) Gel electrophoresis
b) PFGE
c) Blotting
d) PCR
Answer: c)
Explanation: Blotting is used to transfer nucleic acids from gels to membranes for
further analysis. Nucleic acid labeling and hybridization have formed the basis for a
range of experimental techniques.
2. Blotting describes the __________ of nucleic acids.
a) Monitoring
b) Immobilization
c) Racing
d) Comparison
Answer: b)
Explanation: Blotting describes the immobilization of sample nucleic acids on to a solid
support, generally on nylon or nitrocellulose membrane.
3. Which membrane is used in blotting?
a) Agarose
b) Sucrose
c) Polythene
d) Nylon
Answer: d)
Explanation: The main aim of blotting is immobilization of the nucleic acid samples on
a membrane. The membrane must promote binding.
4. Which of the following is used as targets in the blotting techniques?
a) Nucleic acids
b) Agarose
c) Proteins
d) E. coli
Answer: a)
Explanation: The blotted nucleic acids are then used as targets in subsequent
hybridization experiments. There are a few blotting procedures.
5. Which of the following is used for the analysis of compositional properties of DNA?
a) Southern blotting
b) Northern blotting
c) PCR
d) CHEF
Answer: a)
Explanation: Southern blotting is the method used to transfer DNA from agarose gels
to membranes so that the compositional properties of DNA can be analyzed.
6. When was the original method of southern blotting developed?
a) 1975

2. b) 1964
c) 1954
d) 1944
Answer: a)
Explanation: The original method for southern blotting was developed in 1975, for
detecting fragments in an agarose gel that are complementary to a given RNA or DNA.
7. Southern blotting cannot be used for RNA molecules.
a) True
b) False
Answer: b)
Explanation: Southern method was developed as a variation to the Northern method of
DNA analysis. Southern blotting is solely used for RNA.
8. In southern blotting ___________ is present in the reservoir.
a) DNA
b) Buffer
c) Gel
d) Agarose
Answer: b)
Explanation: In the southern blotting technique, the agarose gel is mounted on filter
paper wick which dips into a reservoir containing a transfer buffer.
9. The DNA molecules are immobilized on the _____________ in southern blotting
technique.
a) Reservoir
b) Gel
c) Tray
d) Membrane
Answer: d)
Explanation: The DNA molecules are carried out of the gel by the buffer flow and
immobilized on the membrane. Initially, nitrocellulose was used as the membrane.
10. Which membranes have greater binding capacity than nitrocellulose membranes?
a) Sucrose
b) Agarose
c) Nylon
d) Teflon
Answer: c)
Explanation: The main drawback of nitrocellulose membranes is their fragile nature.
Supporting nylon membranes have a greater binding capacity and high tensile strength.
11. Larger DNA fragments require a ___________ transfer time.
a) Longer
b) Shorter
c) Medium
d) Very high
Answer: a)
Explanation: Large DNA fragments, greater than 10 kb require a longer transfer time
than short fragments. Uniform transfer hence must be allowed.

3. 12. The depurination treatment in blotting, involves the use of HCl and ____________
a) Alkali
b) Acid
c) Proteins
d) Nucleic acids
Answer: a)
Explanation: To allow uniform transfer of a wide range of DNA fragment sizes, the
electrophoresed DNA is exposed to short depurination treatment with HCl followed by
alkali.
13. The depurination treatment __________ the DNA fragments.
a) Increases
b) Shortens
c) Inactivates
d) Fluoresces
Answer: b)
Explanation: The depurination treatment shortens the DNA fragments by alkaline
hydrolysis at depurinated sites. It also denatures the fragments.
14. Depurination denatures the DNA fragments.
a) True
b) False
Answer: a)
Explanation: Depurination denatures the fragments prior to transfer, ensuring that they
are in the single stranded state and accessible for probing.
15. Gel is _____________ in neutralizing solution prior to blotting.
a) Inactivated
b) Boiled
c) Polymerized
d) Equilibrated
Answer: d)
Explanation: The gel is equilibrated in neutralizing solution prior to blotting. This is the
final step in the southern blotting technique.
16) DNA is the polydeoxynucleotides that contain mono-deoxynucleotides namely
dAMP, dGMP, dCMP, dTMP. Which one of the following is NOT true regarding
DNA?
a) DNA is double-stranded.
b) The nucleotides are covalently linked by 3'-5' phosphodiester bond.
c) Both strands of DNA are arranged parallel.
d) DNA has a helical structure.
Answer-c) Both strands of DNA are arranged parallel
17) Phosphodiester bonds are cleaved by nucleases a group of enzymes present in the
cells. Which of the following is FALSE about nucleases?
a) Nucleases catalyze the hydrolytic cleavage of the phosphodiester linkages.
b) Nucleases can be exonuclease and endonucleases.

4. c) Exonucleases cleave the chain by removing individual nucleotides from the 3' or 5'
end.
d) Exonucleases cleave the chain randomly between any nucleotides.
Answer:d) Exonucleases cleave the chain randomly between any nucleotides
18) Chromatin is a structural complex present in eukaryotes. The chromatin consists of the
following components, EXCEPT:
a) DNA
b) RNA
c) Histone proteins
d) None of the Above
Answer-b) RNA
19) The plasmids are the extrachromosomal materials that serve the following
function, EXCEPT
a) May carry genes responsible for antibiotic resistance
b) May facilitate the genetic information transfer
c) Necessary for cell replication and division
d) None of the above
Answer-c) Necessary for cell replication and division
20) Which of the following is not the core submit of the octamer histone protein?
a) H1
b)H2A
c)H2B
d)H3
Answer-a) H1
21) Which of the following process does not occur in prokaryotes?
a) Replication
b) Splicing
c) Conjugation
d)Transformation
Answer-b) Splicing
22) Among them, which is the “palindrome” Sequence?
a) 5’-GATTAC-3’
b) 5’-GCATTA-3’
c) 5’-GAATTC-3’
d) 5’-GTCTAA-3’
Answer-d) 5’-GTCTAA-3’
23) The base that is not present in the RNA coding sequence is...................................
a) Adenine

5. b) Guanine
c) Thiamine
d) Cytosine
Answer-c) Thiamine
24). Fluorescence In Situ Hybridization techniques are used for the detection of....................
a) Cholesterol
b) Glycoprotein
c) Chromosome
d) Glycogen
Answer-a) Chromosome
25) Southern Blot is used to detect......................................
a) RNA
b) DNA
c) Proteins
d) Chromosomes
Answer-b) DNA
26) Which of the following is not the cloning vector utilized in recombinant DNA
technology?
a) Plasmid
b) Cosmids
c) Bacterial Artificial Chromosomes
d) Yeast Intact chromosomes
Answer-d) Yeast Intact chromosomes
27) Which of the following term is not true regarding restriction enzymes used in
recombinant DNA technology?
a) They are site-specific
b) They recognize palindromic sequences
c) They are ATP dependent nucleases
d) They are endonucleases
Answer-c) They are ATP dependent nucleases
28) Which of the following libraries provides information about functional genomics?
a) DNA library
b) cDNA library
c) RNA library
d) Protein library
Answer-b) cDNA library
29) Which of the following DNA technology is used to identify the suspects in the criminal
investigation?

6. a) Western blot
b) Southern blot
c) Northern blot
d) RFLP (Restriction fragment length polymorphism)
Answer-d) RFLP
30) Which of the following DNA technology is used for the amplification of DNA in vitro?
a) Polymerase Chain Reaction
b) Restriction Analysis
c) Northern blot
d) Southern blot
Answer: a) Polymerase Chain Reaction
31) The blotting technique which is used to detect the RNA in a sample is.................
a) Southern blotting
b) Eastern blotting
c) Northern blotting
d) Western blotting
Answer-c) Northern blotting
32). When performing a western blot, what is the purpose of adding a secondary
antibody?
a) Ensure that the primary antibody binds properly to the sample
b) Allow for detection of the protein sample
c) Block any interfering noise coming from the membrane
d) Separate the sample from other proteins
Answer: b)
Explanation: Typically, the secondary antibody is designed to have either a fluorescent or
colorimetric tag to allow for detection. The primary antibody binds to the protein of interest,
but (usually) does not have its own tag. The protein samples have already been properly
separated during electrophoresis. Noise is blocked via various methods, but not by the
secondary antibody. The secondary antibody does not influence the binding of the primary
antibody.
33) A student researcher overexpresses an exogenous protein in cell culture and wants to
determine if that protein, is in fact, overexpressed. What technique would best
demonstrate that this protein is expressed in these cells?
a) Western blot
b) Electrophoretic mobility shift assay (EMSA)
c) None of the other answers
d) Northern blot
e) Southern blot
Answer: a)

7. Explanation: The correct answer is Western blot. Western blots utilize antibodies to detect
specific proteins in a cell lysate. Northern blots detect specific RNA within a sample, whereas
Southern blots detect specific DNA sequences within a sample. An EMSA detects whether or
not a protein is active, and therefore can bind a specific sequence of DNA.
34) After proteins are run on an SDS-PAGE gel, a transfer is executed. What is the purpose
of the transfer in Western blot protocol?
a) Visualize the proteins run on the gel
b) Denature the proteins in the sample
c) Probe the gel with an antibody to detect a protein of interest
d) None of the other anwers
e) Move proteins from the SDS-PAGE gel to a nitrocellulose membrane.
Correct answer: Move proteins from the SDS-PAGE gel to a nitrocellulose membrane.
Explanation:After proteins are run on an SDS-PAGE gel and separated by size, they are
transferred to a nitrocellulose membrane. This exposes the proteins so that an antibody can
recognize and bind to the protein of interest. Once the antibody is bound, a fluorescent
secondary conjugated antibody will facilitate the visualization of the protein of interest.
35) Which of the following is not a similarity between enzyme-linked immunosorbent assays
(ELISAs) and western blots, two common protein detection methods?
Possible Answers:
a) Detection of protein using antibodies specifically generated against antigens
b) Tissue sample must be homogenized and the protein extracted to utilize the assay
c) Requirement of antibodies conjugated to a marker for detection
d) Information from the assays can be made quantitative with the right controls
e) Requirement that the protein is denatured prior to detection
Correct answer: Requirement that the protein is denatured prior to detection
Explanation: The major difference between ELISA and western blot is the fact that ELISA
detects naive protein in its original conformation, while western requires denaturation of the
protein by SDS-PAGE prior to detection. This makes western blotting more stringent and better
for quantification, although both assays can quantitatively assess protein levels if done
properly.
36) A researcher is working with a protein that contains four subunits of differing molecular
weights. If the researcher performs SDS-PAGE, how many distinct bands should he see on
the gel?
Possible Answers:
a) Two
b) One
c) Four

8. d) Three
Correct answer: Four
Explanation: SDS-PAGE requires that proteins are denatured before they are run through the
gel, typically by the addition of detergents and then heating the sample. Since the protein has
four subunits that are all different molecular weights, we would see four distinct bands that
represent the four subunits. If the subunits had the same molecular weight, we would only see
one band.
37) Which of the following is a primary factor that dictates how far a protein will migrate
during SDS-PAGE?
Possible Answers:
a) Degree of tertiary structure
b) Degree of secondary structure
c) Size
d) Number of subunits
Correct answer: Size
Explanation: The primary factor dictating how far a protein will migrate during SDS-PAGE is
the size of the protein. One of the key features of SDS-PAGE is that the protein sample is
denatured and covered in a detergent prior to being run through the gel. This essentially
eliminates any complications from the degree of folding or the number of subunits. In fact,
subunits will migrate according to their own molecular weights.
38) Which of the following is true about SDS-PAGE?
Possible Answers:
a) Staining with ethidium bromide allows visualization of results
b) The main ingredient in the gel is agarose
c) It is used to anaylze DNA fragments
d) It requires a protein-denaturing gel
e) It separates proteins by charge
Correct answer: It requires a protein-denaturing gel
Explanation: SDS-PAGE requires a denaturing protein gel that separates proteins based on
size. The primary ingredients are polyacrylamide and sodium dodecyl sulfate—SDS-PAGE
refers to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In order to visualize the
results, proteins separated via SDS-PAGE are transferred to a nitrocellulose membrane, where
they are probed with antibodies for a specific protein of interest.
39) As opposed to electrophoresis with a more standard agar gel, what does polyacrylamide
gel electrophoresis (PAGE) allow for when working with DNA?
Possible Answers:
a) Staining the DNA for visualization
b) Running multiple lanes in one gel

9. c) Resolution down to DNA strands with single base length differences
d) Running multiple DNA strands in a single gel lane
e) None of these
Correct answer: Resolution down to DNA strands with single base length differences
Explanation: Polyacrylamide gels allow for resolution of DNA strands down to single base pair
differences. All these other options are applicable to any kind of gel electrophoresis. This
property of polyacrylamide allowed for some of the earliest forms of Sanger sequencing, in
which DNA sequences were read by their respective chain lengths across a 4 column gel (with
one column each for adenine, cytosine, guanine, and thymine).
40) Which of the following techniques would be most useful to study gene expression?
Possible Answers:
a) Southern blot
b) Northern blot
c) Western blot
d) Eastern blot
Correct answer: Northern blot
Explanation: In order to study gene expression it would be useful to quantify the expression of
a specific RNA transcript. All of the blotting techniques follow similar procedures, but differ
in the macromolecule they separate or the information they obtain. Southern blotting is used
for DNA fragments, western blotting is used for proteins, and eastern blotting is used to look
at post-translational modifications. Northern blotting would be the most useful in this question,
as it is used to look at RNA fragments.
41) Which of the following probes are most commonly used in southern blotting?
Possible Answers:
a) Nucleic acids
b) Biotin-binding proteins
c) Phosphorous-32
d) Antibodies
Correct answer: Nucleic acids
Explanation: Southern blotting is a technique used to detect a specific DNA sequence
in a sample. The sample is run on an agarose gel and transferred to a membrane. A labeled
nucleic acid probe is then incubated with the membrane. The probe carries a tag for
identification and will only bind to the target region of DNA. If the tag is identified, then the
researcher can conclude that the target gene is present in the sample.
Antibodies are most commonly used to detect specific proteins in western blotting.
Biotin-binding proteins have wide uses in both detection and purification procedures.
Phosphorous-32 is commonly used to label nucleotides (such as GTP) to perform enzymatic
assays.