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Free download in PDF Structure of dsDNA Multiple Choice Questions & Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(1)
Which of them is used to introduce negative supercoiling in DNA?
[A]
Type 1 topoisomerase
[B]
Ethidium bromide
[C]
Gyrase/ type 2 topoisomerase
[D]
SYBR gold
Answer: Gyrase/ type 2 topoisomerase
(2)
What is the term given to the supercoiling of circular DNA?
[A]
Twist number
[B]
Linking number
[C]
Writhe number
[D]
Cross-linking
(3)
Which of this factor is not responsible for thermal denaturation of DNA?
[A]
PH
[B]
Temperature
[C]
Ionic strength
[D]
Humidity
(4)
The stability and formation of G-quadruplex depends on __________
[A]
Monovalent cation
[B]
Divalent cation
[C]
Bivalent cation
[D]
Pentavalent ion
Answer: Monovalent cation
(5)
Name the nitrogenous base which is found in abundance in G-quadruplex?
[A]
Adenine
[B]
Guanine
[C]
Cytosine
[D]
Thymine
(6)
The third strand of triple helix is paired in which scheme?
[A]
Hoogsteen base pair scheme
[B]
Intermolecular base pair scheme
[C]
Intramolecular base pair scheme
[D]
G-quartet scheme
Answer: Hoogsteen base pair scheme
(7)
Which one of the following statement is INCORRECT for Z-DNA?
[A]
Left-handed DNA
[B]
Mostly found in alternating purine-pyrimidine sequences
[C]
Only one deep, narrow groove
[D]
Anti glycosidic bond conformation
Answer: Anti glycosidic bond conformation
(8)
How many base pairs are there in every helical turn of Watson-Crick double helix model?
[A]
32.3
[B]
11.6
[C]
20
[D]
10.4
(9)
Which form of DNA is described by Watson-Crick model?
[A]
B-DNA
[B]
Z-DNA
[C]
A-DNA
[D]
Quadraplex DNA
(10)
Who described the structure of DNA double helix?
[A]
Peter Mitchell
[B]
Andre Jagendorf
[C]
Ernest Uribe
[D]
Watson and Crick
(11)
Levene investigated and found that the nucleic acid is composed of poly-nucleotides and each nucleotide is composed of one base, a sugar molecule and a phosphate. This was performed on the genome of________________
[A]
Bacteria
[B]
Fungi
[C]
WBCs
[D]
Yeast
(12)
In the late 1970s non double helical form of DNA was also suggested but was discarded on the basis of certain factors. Which of the following is not a factor responsible?
[A]
X-ray crystallography
[B]
Nuclein
[C]
Topoisomerase
[D]
Nucleosome core particle
(13)
With respect to the importance of hydrogen bonding and DNA double helix stability, which of the following statements is false?
[A]
Favorable tautomeric form of nucleotide bases
[B]
Contributes to the thermodynamic stability
[C]
Decreases the entropy
[D]
Specificity of base pairing
Answer: Decreases the entropy
(14)
In a DNA double helix the bases are held together by hydrogen bonds. These hydrogen bonds are _________
[A]
Covalent bonds
[B]
Non-covalent bonds
[C]
Ionic bonds
[D]
Van der Waals forces
Answer: Non-covalent bonds
(15)
The hydrogen bonds formed during A and T bonding occurs between C6NH2 of A and _____
[A]
C4O of T
[B]
PO3–
[C]
C6O of A
[D]
C1O of T
(16)
What should be the complementary strand of 3’….ATGGCTTGA….5’?
[A]
3’….TACCGAACT….5’
[B]
5’….TACCGAACT….3’
[C]
3’….TAGGCAAGT….5’
[D]
5’….TAGGCAAGT….3’
Answer: 5’….TACCGAACT….3’
(17)
In 1952, an unambiguous established work in the laboratory of Alexander Todd led to the discovery of _____________
[A]
Chemical nature of DNA
[B]
X-ray diffraction structure of DNA
[C]
3’-5’ phosphodiester linkage regularly links the nucleotides of DNA
[D]
Nucleic acid strands are held together by hydrogen bonds
Answer: 3’-5’ phosphodiester linkage regularly links the nucleotides of DNA
(18)
In early 1950s high quality X-ray diffraction photographs of DNA suggesting the DNA being double helix and composed of two nucleotide strands. Who took those photographs?
[A]
Rosalind Franklin
[B]
William Asbury
[C]
Francis H. Crick and James D. Watson
[D]
Rosalind Franklin and Maurice Wilkins
Answer: Rosalind Franklin and Maurice Wilkins
(19)
The first X-ray diffraction patterns of DNA were taken in 1938 by ___________
[A]
William Asbury
[B]
Rosalind Franklin
[C]
Francis H. Crick
[D]
Linus Pauling
(20)
A nucleoside is composed of
[A]
a base+ a sugar
[B]
a base+ a sugar+ phosphate
[C]
a base+ a phosphate
[D]
none of these
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