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 |
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 |