What radioactive isotope was used by Meselson and Stahl to label DNA in their experiment?
1. | 35S | 2. | 15N |
3. | 32P | 4. | None |
The density gradient in Meselson and Stahl's experiment was of:
1. | NH4Cl | 2. | CsCl |
3. | KCl | 4. | BaCl2 |
The daughter DNA that was extracted from the culture one generation after the transfer from 15N to 14N medium had:
1. | Low density |
2. | Intermediate density |
3. | High density |
4. | One had low and another had high density |
If E.coli was allowed to grow for 80 minutes after transfer from 15N to 14N medium, the number of hybrid density DNA molecules would be:
1. | 2 | 2. | 16 |
3. | 14 | 4. | 8 |
I: | The result at the end of 20 minutes excludes the ‘conservative’ mode of DNA replication. |
II: | The result at the end of 40 minutes excludes the ‘dispersive’ mode of DNA replication. |
Any mistakes during DNA replication by the enzyme would result into:
1. | Cancer | 2. | Apoptosis |
3. | Cell fragmentation | 4. | Mutation |
Reverse transcriptase is a:
1. | DNA-dependent RNA polymerase |
2. | RNA-dependent DNA polymerase |
3. | RNA-dependent RNA polymerase |
4. | DNA-dependent DNA polymerase |
Assertion (A): | Deoxyribonulceoside triphosphates provide energy for polymerization reactions during the replication of DNA. |
Reason (R): | The two terminal phosphates in a deoxyribonucleoside triphosphate are high-energy phosphates, the same as in the case of ATP. |
1. | (A) is True but (R) is False. |
2. | Both (A) and (R) are False. |
3. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
4. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
Consider the following statements:
I. | Deoxyribonucleoside triphosphates act as substrates as well as provide energy for polymerization reaction during DNA replication. |
II. | The replication of DNA is both semiconservative and semi-discontinuous |
III. | In bacterial DNA replication, there are multiple ori and replication fork moving bi-directionally |
Which of the above statements are true?
1. | I and II only | 2. | I and III only |
3. | II and III only | 4. | I, II and III |
Assertion (A): | For long DNA molecules, the replication occurs within a small opening of the DNA helix, referred to as the replication fork. |
Reason (R): | The DNA polymerases on their own cannot initiate the process of replication. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | Both (A) and (R) are False. |
4. | (A) is True but (R) is False. |