Q. No.The enzyme DNA ligase, important in rDNA procedures, catalyzes the formation of:
1. N- Glycosidic 2. Hydrogen 3. Phosphodiester 4. Ester
A donor DNA and plasmid vector DNA of E. coli are cut by EcoRI. The plasmid contains genes for resistance to ampicillin and tetracycline. The ECoRI recognition sequence lies within the gene for tetracycline resistance. Ligase is used, and the recombinant DNA is produced. The plasmids are transferred to E.coli with the help of electroporation. Samples of the bacterial colonies are then grown in four different media: nutrient medium plus ampicillin, nutrient medium plus tetracycline, nutrient medium plus ampicillin and tetracycline, and nutrient medium without antibiotics. Non-recombinant transformants will grow on:
| 1. | the nutrient medium plus ampicillin, but not on the medium containing tetracycline. |
| 2. | only on the medium containing both antibiotics. |
| 3. | on the medium containing tetracycline, but not on the medium containing ampicillin. |
| 4. | on all four types of mediums. |
A gene of interest is inserted into the lac Z gene in a plasmid also containing a tetracycline-resistant gene. If the transformed bacteria are plated on a medium containing tetracycline and X-gal, the recombinant plasmids will be shown as:
| 1. | a colony which did not grow on the tetracycline plates |
| 2. | a white colony on the tetracycline plates |
| 3. | a blue colony on the tetracycline plates |
| 4. | a black colony on the tetracycline plates |
DNA fragments resulting from restriction enzyme digestion are moved through agar gel during electrophoresis. Which of the following modifications to the fragments will not affect the rate of their movement?
1. Neutralizing the negative charge
2. Increasing length
3. Changing the base composition
4. Decreasing length
If we are able to link an alien piece of DNA with bacteriophage or plasmid DNA, we can multiply its number:
| 1. | more than the number of copy number of bacteriophages in the cells and equal to the copy number of plasmid in the cell. |
| 2. | equal to the number of copy number of bacteriophages in the cells and equal to the copy number of plasmid in the cell. |
| 3. | equal to the number of copy number of bacteriophages in the cells and less than the copy number of plasmid in the cell. |
| 4. | less than the number of copy number of bacteriophages in the cells and more than the copy number of plasmid in the cell. |
Restriction enzymes do not act on the DNA of the Host cell in which they are produced because:
| 1. | Host DNA is packed into chromosomes |
| 2. | Restriction enzymes are ineffective on host DNA |
| 3. | Host DNA does not have the restriction site for the Restriction enzymes |
| 4. | Restriction site of host DNA is methylated |
1. Agrobacterium tumefaciens
2. Escherichia coli
3. Bacillus thuringiensis
4. Xanthomonas citri
Which of the following can be used to induce competence for getting a bacterial cell transformed during rDNA procedures?
| 1. | A divalent cation | 2. | Ethidium bromide |
| 3. | Polyethylene glycol | 4. | Anionic proteins |
In microinjection, the rDNA :
| 1. | coats the micropellets and is used in biolistics to transform plant cells |
| 2. | is directly injected into the cytoplasm of a plant or an animal cell |
| 3. | is delivered in the vicinity of the plasma membrane of the cell (to be transformed) |
| 4. | is directly injected into the nucleus of an animal cell |
To isolate DNA in pure form from a bacterial cell, it should initially be treated with:
| 1. | Proteases and RNase but not DNase | 2. | Lysozyme |
| 3. | Restriction endonuclease | 4. | DNA ligase |
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