Question

What are selectable markers? What is their use in genetic engineering?

Answer 1

A selectable marker helps to identify and delete non-transformants and allows processors to expand selectively. A selectable marker is a gene inserted into a cell, in particular a bacterium or a cultured cell, which confers a trait appropriate for artificial selection.

Complete answer:
Genetic engineering is a process by which recombinant DNA technology is used to change the genetic makeup of the organism. Traditionally, humans have indirectly manipulated genomes by regulating the reproduction and choosing offspring with the desired traits. Genetic modification requires the active control of one or more genes. Very frequently, a gene from another animal is applied to the genome of the organism to give it the desired phenotype.

Selectable marker genes are a critical feature of most of the transition protocols. They are released along with the gene of interest, either on the same plasmid or on a different plasmid. For the maintenance of the plasmid in the cell, a selectable marker is necessary. Owing to the presence of a selective marker, the plasmid becomes beneficial to the cell. Only cells containing plasmids with the required selectable marker will survive under selective conditions. Genes that impart resistance to multiple antibiotics are widely used as selective markers in the cloning of vectors. A broad variety of selectable marker regimes is available and is especially important in species where transformation efficiency is weak.

Note: By inserting a selectable marker gene into the bacterial cells, colonies that have successfully ingested the plasmid are more likely to gain resistance to the particular antibiotic, whereas those that do not, ultimately perish. Surviving colonies will then be separated, propagated and used for future downstream experiments.