The backbone of a polynucleotide chain is made of:
1. | Sugar and nitrogenous bases |
2. | Phosphate and nitrogenous bases |
3. | Sugar and phosphate |
4. | Sugar, phosphate, and nitrogenous bases |
DNA was first identified by:
1. | Friedrich Meischer | 2. | Phoebus Levene |
3. | Linus Pauling | 4. | Erwin Chargaff |
Watson and Crick based their model of DNA on X-ray diffraction data produced by:
1. | Hershey and Chase | 2. | Marie Curie and Pierre Curie |
3. | Franklin and Wilkins | 4. | Meselson and Stahl |
According to Erwin Chargaff, in a double-stranded DNA
1. | The ratios between Adenine and Thymine, and, Guanine and Cytosine are constant and equal. |
2. | The ratios between Adenine and Thymine, and, Guanine and Cytosine are constant but are not equal to one. |
3. | The ratios between Adenine and Guanine, and, Thymine and Cytosine are constant and equal. |
4. | The ratios between Adenine and Guanine, and, Thymine and Cytosine are constant but are not equal to one. |
The base pairing in a double stranded DNA is correctly described as:
1. | Similar | 2. | Identical |
3. | Complementary | 4. | Synergistic |
If each strand of a dsDNA acts as a template for a new strand, the two daughter DNAs will be:
1. | Complementary to each other |
2. | Identical to the parental DNA |
3. | Similar to each other |
4. | Complementary to the parental DNA |
Which of the following is not a feature of the double helix model of DNA?
1. | The two chains have anti-parallel polarity |
2. | A purine always comes opposite to a pyrimidine |
3. | The pitch of the DNA is 3.4 nm |
4. | The two chains are coiled in a left handed fashion |
Statement I: | A shows the hydrogen bonds where a triple bond links Guanine and Cytosine and a double bond links Adenine and Thymine. |
Statement II: | If Adenine in such a dsDNA molecule is found to be 20 %, the amount of Cytosine in this ds DNA molecule is expected to be 20 %. |
I: | A represents a base pair where the plane of one base pair stacks over the other in the double helix giving the helix more stability in addition to hydrogen bonds. |
II: | There are 10 base pairs in one complete turn of B-dNA. |
III: | B is the backbone constituted by sugar-phosphate. |
IV: | The two strands are parallel-oriented in the same direction with respect to each other. |
V: | The diameter is uniform, around 2.0nm. |
1. | Only I, II and III | 2. | Only II, III, IV and V |
3. | Only I, II, III and V | 4. | I, II, III, IV and V |
The distance between a base pair in the DNA double helix is approximately:
1. | 2.0 nm | 2. | 0.34 nm |
3. | 20 nm | 4. | 3.4 nm |