Which type of organisms can undergo horizontal gene transfer?

The correct answer is that bacteria and viruses are capable of undergoing horizontal gene transfer. Horizontal gene transfer (HGT) refers to the movement of genetic material between organisms other than through traditional inheritance from parent to offspring.

Bacteria primarily utilize several methods for HGT, including transformation (taking up naked DNA from the environment), transduction (gene transfer facilitated by bacteriophages), and conjugation (direct transfer of DNA between bacterial cells through pilus connections). This ability allows bacteria to rapidly acquire new traits, such as antibiotic resistance, which can enhance their survival in changing environments.

Viruses, particularly bacteriophages, can also contribute to horizontal gene transfer by integrating their genetic material into the genomes of bacteria they infect, thereby introducing new genes into bacterial populations.

While all organisms can technically exchange genetic material, the mechanisms of horizontal gene transfer differ significantly across life forms and are most pronounced in bacteria and viruses. For instance, multicellular organisms, including mammals, primarily rely on vertical gene transfer (from parent to offspring) for the exchange of genetic material.

Therefore, the involvement of both bacteria and viruses in horizontal gene transfer is a fundamental concept in microbiology, particularly in understanding evolution, adaptability, and the spread of traits such as resistance.