Types of Genetic Transfer Between Organisms

Genetic transfer occurs when genetic information is transferred from one organism to another. 

There are two types of genetic transfer: vertical and horizontal. 

Vertical gene transfer, the most common of the two, is the transmission of genetic information from one generation to the next. 

Vertical gene transfer occurs in sexually reproducing organisms, where they pass roughly half of the DNA onto the offspring, and in asexually reproducing organisms, which produce genetically identical progeny.  

Horizontal gene transfer, conversely, occurs when genetic material from one organism is introduced to another organism of the same generation. 

In the case of some prokaryotic species, such as bacteria, horizontal gene transfer can occur between different species.

Horizontal gene transfer in prokaryotes occurs via three mechanisms: transformation, transduction, and conjugation. 

In transformation, a prokaryotic cell takes up naked DNA from the environment.

During transduction, viruses, bacteriophages in this example, degrade their host’s DNA. Small lengths of the host’s DNA can be packaged into the bacteriophage’s progeny before the host cell lyses. 

The viral progeny then go on to infect more bacterial cells, thus becoming inadvertent mediators to transduction.

In conjugation, DNA is directly transferred from one cell to another via a structure called the sex pilus. 

While conjugation is a form of ‘mating’ for asexually reproducing organisms, it is not true sexual reproduction because there are no gametes exchanged or offspring produced. 

Each of these mechanisms can be observed in nature and have laboratory applications.

For example, conjugation can be used to confer antibiotic resistance from one bacterial strain to another, resulting in strains that can be resistant to multiple antibiotics.