You are trying to clone a piece of DNA into a plasmid vector that exhibits blue-white selection.Following ligation and transformation,you plate the host cells onto several plates containing the appropriate selective media.The next day you examine the bacterial colonies that grew.Which of the following plates should you select to proceed with the analysis of possible transformants?
A)3 white colonies,50 blue colonies
B)97 white colonies,105 blue colonies
C)43 white colonies,6 blue colonies
D)238 blue colonies

Question

Quizplus · Accepted Answer

The presence of white colonies indicates successful ligation and transformation of the vector with the insert, as the insert disrupts the β-galactosidase gene that produces blue pigment. Therefore, the higher number of white colonies in option B could indicate a high background of non-transformed cells, which may reduce the chances of finding a desired transformant. On the other hand, option C has a good ratio of white to blue colonies, indicating a successful transformation rate with less background noise. Option A has too many blue colonies while option D has no white colonies, indicating unsuccessful ligation or transformation.

You Are Trying to Clone a Piece of DNA into a Plasmid