Which genetic modification method is most specific for inserting a transgene at a particular chromosomal location?

Which genetic modification method is most specific for inserting a transgene at a particular chromosomal location?

• A. Transgene transfer
• B. Phenotype copy
• C. Pronuclear injection
• D. Gene-targeted mutation

Answer: (D)

To place a transgene at a specific spot in the genome, you need a method that uses targeted sequence matching to guide insertion. Gene-targeted mutation does this by using DNA constructs with regions that are homologous to the chosen locus, so the cell’s repair mechanisms incorporate the transgene precisely at that location. This locus-specific integration provides predictable expression and minimizes positional effects that occur when DNA inserts randomly. In contrast, introducing DNA into a fertilized egg (pronuclear injection) tends to result in random integration, and general “transgene transfer” isn’t inherently site-specific, while “phenotype copy” isn’t a standard technique. So, gene-targeted mutation is the method that achieves insertion at a particular chromosomal location.

To place a transgene at a specific spot in the genome, you need a method that uses targeted sequence matching to guide insertion. Gene-targeted mutation does this by using DNA constructs with regions that are homologous to the chosen locus, so the cell’s repair mechanisms incorporate the transgene precisely at that location. This locus-specific integration provides predictable expression and minimizes positional effects that occur when DNA inserts randomly. In contrast, introducing DNA into a fertilized egg (pronuclear injection) tends to result in random integration, and general “transgene transfer” isn’t inherently site-specific, while “phenotype copy” isn’t a standard technique. So, gene-targeted mutation is the method that achieves insertion at a particular chromosomal location.