The DNA dependent polymerases catalyze:
1. | Only in 3’ – 5’ direction |
2. | Only in 5’ – 3’ direction |
3. | In both directions |
4. | In neither directions |
DNA is structurally and chemically more stable than RNA because of the following except:
1. | It has thymine instead of uracil |
2. | 2’ –OH is absent in DNA |
3. | It replicates itself based on complementary base pairing |
4. | It does not have any catalytic role |
Who proposed a semi-conservative mode of replication for DNA?
1. | Watson and Crick | 2. | Meselson and Stahl |
3. | Hershey and Chase | 4. | Beadle and Tatum |
A transcription unit does not contain:
1. | Promoter | 2. | Operator |
3. | Structural gene | 4. | Terminator |
The discontinuously synthesized DNA fragments are later joined by:
1. | DNA helicase | 2. | Topoisomerase |
3. | DNA ligase | 4. | DNA polymerase |
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 |
In eukaryotes, the sequences that appear in mature or processed mRNA are called:
1. | Introns | 2. | Cistrons |
3. | Exons | 4. | Mutons |
What radioactive isotope was used by Meselson and Stahl to label DNA in their experiment?
1. | 35S | 2. | 15N |
3. | 32P | 4. | None |
Which of the following acts as the substrate and provides energy for DNA replication?
1. | Dideoxyribonucleoside triphospahtes |
2. | Ribonucleoside triphosphates |
3. | Deoxyribonucleoside triphospahtes |
4. | Deoxyribonucleotide triphosphates |
Which of the following is not a stop codon?
1. | UAA | 2. | UGA |
3. | UAC | 4. | UAG |