The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid of which of the following organism?
1. Escherichia coli
2. Bacillus thuringiensis
3. Salmonella typhimurium
4. Agrobacterium tumefaciens
In a cell, the separation of DNA strands is brought about by the enzyme DNA helicase, whereas in PCR, the separation of DNA strands is due to :
1. High temperature
2. Two sets of Primers
3. Taq DNA polymerase
4. Deoxynucleotides
Identify the properties of a good vector used in rDNA technology:
| (a) | It should have origin of replication supporting a high copy number |
| (b) | It should have preferably more than '2' recognition sites |
| (c) | The restriction sites in vector should be in the antibiotic- resistant genes |
| (d) | It should have suitable marker genes |
| (e) | It should be easy to isolate and purify |
Choose the most appropriate answer from the options given below:
1. (a), (c) and (e) only| 1. | The bacterium does not contain the specific recognition sequence |
| 2. | The DNA is packed with histones |
| 3. | The specific recognition sequences are masked with methyl groups |
| 4. | Restriction endonucleases cut viral DNA only |
| Assertion (A): | When a particular restriction enzyme cuts strands of DNA, overhanging stretches or sticky ends are formed. |
| Reason (R): | Some restriction enzymes cut the strand of DNA a little away from the centre of palindromic site. |
| 1. | Both (A) and (R) are True and (R) correctly explains (A). |
| 2. | Both (A) and (R) are True and (R) does not correctly explain (A). |
| 3. | (A) is True, (R) is False. |
| 4. | (A) is False, (R) is True. |