The ability to replace the wildtype alleles with a knockout allele in mice has enabled researchers to carry out important reverse genetics studies on gene function. Please select all of the statements below which correctly describe the creation of gene knockout mice. Multiple answers are possible, and partial credit will be given. A.Illegitimate recombinants have the knockout allele randomly inserted and do not replace the wildtype alleles and may potentially insert into other genes and confound the analysis. B.Resistance to the anti-viral drug ganciclovir indicates that homologous recombination has occured. C.Homologous recombinants of the knockout alleles are desired since they will replace the wildtype allele. D.Resistance to neomycin indicates insertion of the knockout allele but does not distinguish between homologous and non-homologous recombinants. E.The embryonic stem cells carrying homologous recombinants of the knockout allele are placed back into a blastocyst and injected into a surrogate mother to produce mice carrying the knockout allele.

The correct statements are,:

B. Resistance to the anti-viral drug ganciclovir indicates that homologous recombination has occurred.

C. Homologous recombinants of the knockout alleles are desired since they will replace the wildtype allele

E. The embryonic stem cells carrying homologous recombinants of the knockout allele are placed back into a blastocyst and injected into a surrogate mother to produce mice carrying the knockout allele.

Explanation:

wrong statements

A. Illegitimate recombinants have the knockout allele randomly inserted and do not replace the wildtype alleles and may potentially insert into other genes and confound the analysis

D. Resistance to neomycin indicates insertion of the knockout allele but does not distinguish between homologous and non-homologous recombinants

A and D are wrong statement due to the fact that Cells that were transformed with a vector containing the neomycin gene and the herpes tk+ gene are grown in a solution that contains neomycin and Ganciclovir in order to distinguish  the transformations that occured through homologous recombination. Any DNA insertion that occurred through  random insersion( illegitimate recombinant) will die because the tests positive for both  neomycin resistant gene and herpes tk+ gene whose gene product reacts with Ganciclovir to produce deadly toxins.

meiosis is the first to occur after the nuclei of opposite of opposite mating types fuse