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Q. No.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 |
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 |
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
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 |
| 1. | 0 | 2. | 23 |
| 3. | 27 | 4. | 46 |
The radius of the double helix of B-DNA [Watson and Crick model] is approximately:
| 1. | 1.0 nm | 2. | 2.0 nm |
| 3. | 0.34 nm | 4. | 3.4 nm |
| 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 |
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Q. No.
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