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Free download in PDF Molecular Basis of Inheritance Objective Type Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams like NEET, AIIMS, JIPMER etc. These short solved questions or quizzes are provided by Gkseries./p>
(1)
Linking number is the sum of which geometric components?
[A]
Twist and writhe
[B]
Toroid and writhe
[C]
Twist and wrap
[D]
Twist and crossover
(2)
3 – dimension structure of cccDNA is ___________
[A]
Nicked
[B]
Supercoiled
[C]
Flat
[D]
Torsionally stressed
Answer: Torsionally stressed
(3)
Plectonomic writhe is __________
[A]
Cylindrical axis winding
[B]
Long axis twisted around itself
[C]
Helical turns of one strand about the other
[D]
Number of encounters of the two strands of a helix
Answer: Long axis twisted around itself
(4)
Interwound writhe and spiral writhe are topologically different.
(5)
Twist and writhe are interconvertible.
(6)
What is the relation between linking number (Lk), writing number (Wr) and twist number (Tw)?
[A]
Lk = Tw – Wr
[B]
Lk = Wr – Tw
[C]
Tw = Lk – Wr
[D]
Tw = Lk + Wr
(7)
How can we remove supercoils from cccDNA?
[A]
Treat with DNase
[B]
Treat with detergent
[C]
Treat with endonuclease
[D]
Application of heat
(8)
If Lk < Lk0 then DNA is ____________
[A]
Relaxed
[B]
Negatively coiled
[C]
Positively coiled
[D]
ΔLk > 0
Answer: Negatively coiled
(9)
What is ΔLk and Lk0 dependent upon?
[A]
Histone concentration
[B]
G : A ratio
[C]
Composition of DNA
[D]
Length of DNA
(10)
Strand separation is easily accomplished in positively supercoiled DNA.
(11)
Which of the following organism has been found to have a positively supercoiled DNA?
[A]
Saurida tumbil
[B]
Monarda didyma
[C]
Thermus aquaticus
[D]
Cyanobacteria
Answer: Thermus aquaticus
(12)
Which of the following is not true about positive supercoils?
[A]
Helps to avoid denaturing
[B]
Over wounded DNA
[C]
Strand separations require low energy
[D]
Rare form of DNA supercoiling
Answer: Strand separations require low energy
(13)
Packaging of DNA around nucleosome is known as ____________
[A]
Toroid writhes
[B]
Twist
[C]
Plectonemic writhes
[D]
Supercoils
(14)
The nucleosome is seen to have negative supercoils.
(15)
Which of the following is known to relax supercoiled DNA?
[A]
Nuclease
[B]
DNase I
[C]
Endonuclease
[D]
Topoisomerase
(16)
With respect to topoisomerases which of the following is true?
[A]
Only of one type
[B]
Never changes linking number
[C]
Requires ATP
[D]
Introduces knots
(17)
Topoisomerases I and II differ only on the number of steps required to change the linking number.
(18)
Which special enzyme introduces negative supercoils in DNA?
[A]
Type I topoisomerase
[B]
Type II topoisomerase
[C]
Gyrase
[D]
Helicase
(19)
Which of the following is not a property of topoisomerase?
[A]
Removal of supercoil
[B]
Helps in DNA replication
[C]
Cannot catenate and decatenate
[D]
Utilizes ATP to change linking number
Answer: Cannot catenate and decatenate
(20)
Topoisomerases introduces catenation to promote cell division.
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