THE MOLECULAR BASIS OF INHERITANCE
RECOMBINANT DNA
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
only bacteria with no ampicillin-resistant plasmid can grow in the media
|
|
|
bacteria with plasmid will die
|
|
|
bacterial colonies will turn blue if lacZ gene is non-functional
|
|
|
bacterial colonies with target gene remain white in medium containing ampicillin and X-gal
|
Detailed explanation-1: -The colonies formed by non-recombinant cells, therefore appear blue in color while the recombinant ones appear white. The desired recombinant colonies can be easily picked and cultured. Isopropyl -D-1-thiogalactopyranoside (IPTG) is used along with X-gal for blue-white screening.
Detailed explanation-2: -Cells transformed with vectors containing recombinant DNA will produce white colonies; cells transformed with non-recombinant plasmids (i.e. only the vector) grow into blue colonies.
Detailed explanation-3: -Using Ampicillin (or other appropriate antibiotic) in your growth medium should prevent bacteria that did not take up the plasmid during the transformation from growing. This way you can be fairly confident that the white colonies you see on your screening plate contain plasmid with insert.
Detailed explanation-4: -However, insertion of a fragment of foreign DNA into the polycloning site of the plasmid almost invariably results in production of an amino-terminal fragment that is no longer capable of -complementation. Bacteria carrying recombinant plasmids therefore form white colonies.