Question

Choose the incorrect statement for cre-lox excision.

(a) The chromosomal copy of the target gene replaces the target gene flanked by loxP sites

(b) The second step is supply of Cre recombinase

(c) Integration of cre takes place under a controllable promoter followed by induction of the promoter

(d) Induction results in expression of cre, recombination along loxP sites and excision of the sequence between

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This is a very interesting question from Cre Lox Excision topic in section Modifications and Mutagenesis of Genetic Engineering

Answer 1

The correct answer is (a) The chromosomal copy of the target gene replaces the target gene flanked by loxP sites

To elaborate: For cre-lox excision, the chromosomal copy of the target gene is replaced by target gene flanked by loxP sites. The second step is supply of cre recombinase. Integration of cre is done by a controllable promoter which is followed by the induction of promoter. This induction results in expression of cre and recombination along loxP sites, leading to excision.