The salient features of the Double-helix structure of DNA include all except:

1.  The two chains are anti-parallel
2.  Complementary base pairing results in a uniform diameter of the helix
3.  The two chains are coiled in a left-handed fashion
4.  The pitch of the helix is 3.4 nm
Subtopic:  DNA Double Helix |
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Identify the correct statements regarding salient features of the Double-helix structure of DNA:

I: Backbone is constituted by nitrogenous bases.
II: The two chains have anti-parallel polarity.
III. There is complementary base pairing between nitrogenous bases.
IV. The two chains are coiled in a left-handed fashion.
V. The plane of one base pair stacks over the other.
 
1. All except I 2. All except I and IV
3. Only II and III 4. Only III
Subtopic:  DNA Double Helix |
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In a DNA strand, two nucleotides are linked through a ___________ linkage to form a dinucleotide.

1. 3’ – 5’ phosphodiester bond

2. 5’ – 3’ phosphodiester bond

3. 1’ N-glycosidic bond

4. Two or three hydrogen bonds

Subtopic:  DNA Double Helix |
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While analysing the DNA of an organism a total number of 5386 nucleotides were found out of which the proportion of different bases were: Adenine = 29%, Guanine = 17%, Cytosine = 32%, Thymine = 17%. Considering Chargaff’s rule it can be concluded that:

1. it is a double-stranded circular DNA
2. It is single-stranded DNA
3. It is a double-stranded linear DNA
4. No conclusion can be drawn
Subtopic:  The DNA | DNA Double Helix |
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A double-stranded DNA molecule globally has percentage base pair equality: A% = T% and G% = C%. One such DNA molecule is found to have 23 % Adenine. What is the expected % of Uracil in this DNA?
1. 0
2. 23
3. 27
4. 46
Subtopic:  DNA Double Helix |
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The radius of the double helix of B-DNA [Watson and Crick model] is approximately:

1.1.0 nm2.2.0 nm
3.0.34 nm4.3.4 nm

Subtopic:  DNA Double Helix |
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Consider the two statements:
I. Ori’s sites in DNA are A-T rich.
II. A-T base pairs have two hydrogen bonds.
1. Both I and II are correct and II explains I
2. Both I and II are correct but II is not a correct explanation of I
3. I is correct and II is incorrect
4. I is incorrect and II is correct
Subtopic:  DNA Double Helix |
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