A gene, whose expression helps to identify transformed cells is known as

1. selectable marker                 

2. vector

3. plasmid                                 

4. structural gene

Subtopic:  Selectable Markers: II | Selectable Markers |
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From NCERT
NEET - 2017
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Bacterial colonies that have a foreign DNA fragment inserted into the plasmid will appear white because-

1.  X-gal can be cleaved by β-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

Subtopic:  Selectable Markers: III | Selectable Markers |
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From NCERT
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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.
Subtopic:  Tools: Vectors: I | Selectable Markers: I | Selectable Markers |
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From NCERT
NEET - 2019
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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.

Subtopic:  Selectable Markers: II | Selectable Markers: III | Selectable Markers |
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From NCERT
AIIMS - 2014
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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

Subtopic:  Selectable Markers |
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From NCERT
AIPMT - 2012
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Insertional inactivation of a gene helps in
a. Identification of recombinant clones
b. Identification of deletion mutants
c. Identification of recombinant transformants
d. Elimination of suppression mutants

Subtopic:  Selectable Markers: III | Selectable Markers |
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From NCERT
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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

Subtopic:  Selectable Markers: III | Selectable Markers |
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From NCERT
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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.

Subtopic:  Selectable Markers: III | Selectable Markers |
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From NCERT
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In the screening process during rDNA experiments, clones that metabolize β-gal turn:

1. Colorless

2. Blue

3. Yellow

4. Green

Subtopic:  Selectable Markers: III | Selectable Markers |
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From NCERT
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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

Subtopic:  Selectable Markers: II | Selectable Markers |
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From NCERT
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