Q. No.A gene, whose expression helps to identify transformed cells is known as
1. selectable marker
2. vector
3. plasmid
4. structural gene
Bacterial colonies that have a foreign DNA fragment inserted into the plasmid will appear white because-
1. X-gal can be cleaved by -galactosidase
2. Lac-Z gene shows insertional inactivation due to insertion of foreign DNA
3. Lac-Z gene is active
4. X-gal can be cleaved by permease
A selectable marker is used to:
| 1. | help in eliminating the non-transformants so that the transformants can be regenerated. |
| 2. | identify the gene for the desired trait in an alien organism. |
| 3. | select a suitable vector for transformation in a specific crop. |
| 4. | mark a gene on a chromosome for isolation using a restriction enzyme. |
How are transformants selected from nontransformants?
| 1. | Presence of more than one recognition site in the vector DNA. |
| 2. | Presence of alien DNA into the vector DNA results into insertional inactivation of selectable marker. |
| 3. | Antibiotic resistance gene gets inactivated due to insertion of alien DNA. |
| 4. | Both 2 and 3. |
In genetic engineering, the antibiotic-resistance gene is used:
1. To select healthy vectors
2. As sequences from where replication starts
3. To keep the cultures free of infection
4. As selectable markers
Insertional inactivation of a gene helps in
| 1. | Identification of recombinant clones |
| 2. | Identification of deletion mutants |
| 3. | Identification of recombinant transformants |
| 4. | Elimination of suppression mutants |
Which of the following would you choose as the safest and least cumbersome selectable marker-
| 1. | Ampicillin resistance gene |
| 2. | Tetracyclin resistance gene |
| 3. | Kanamycin resistance gene |
| 4. | b Galactosidase gene |
Insertional inactivation of the lac Z gene forms-
| 1. | Blue recombinant colonies |
| 2. | Colourless recombinant colonies |
| 3. | Fluorescent green colonies |
| 4. | There is no relation between the lac Z gene and colour of the colony. |
In the screening process during rDNA experiments, clones that metabolize -gal turn:
1. Colorless
2. Blue
3. Yellow
4. Green
Why is a marker gene useful?
| 1. | It shows you whether the gene being added, has been taken up or not. |
| 2. | It's a way of labelling which gene you want to modify. |
| 3. | It sticks with the striker gene. |
| 4. | It marks the position of r-DNA |
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