The process of horizontal gene transfer (otherwise known as HGT) can be
described as one organism acquiring the DNA of another organism. This can be
observed in many types of organisms but is usually performed by prokaryotic
organisms – mainly bacteria. There is a multitude of ways for doing this genetic transfer processes and it
results in an “endosymbiotic” organism, containing both sets of DNA.
Four main methods used by bacteria for Horizontal Gene Transfer (HGT)-
These methods are Conjugation, Transformation, Transduction, and
Introgression. Herein the following section all these four methods are
explained in detail.
- Conjugation in Horizontal Gene
Transfer (HGT), this method occurs through direct contact between two bacterial
cells. It begins with the separation of the DNA to be transported overusing a
section of bi-functional enzymes, which have trans-esterase activities built
into them. Then the DNA is transported across the covalent bond between the two
cells and is unwound by DNA helicase enzymes – ready to now enter the new
bacterium and become integrated into its own DNA makeup.
Conjugation has been observed at different levels,
through many methods of study and these studies show that a majority of DNA is
being transferred via bacterial conjugation is in some way related to
antibiotic resistance in the genetic transfer process.
- Transformation - this is another
genetic transfer process in the
bacterial transformation by which bacteria perform HGT, with natural
transformation is the main process of incorporating another organism’s DNA
into its own genome. This process is observed when a bacterial cell allows a
section of its DNA to leave the cell and allows it then to be taken up by
another, an adjacent bacterium. For acquiring new functions, it can be
integrated into its own DNA.
- Transduction - this method
itself has many stages. In this genetic
transfer process, with the help of a bacteriophage DNA fragment is being
transferred from one bacterium to another bacterium. Major two forms of
transduction are generalized and specialized transduction. Generalized
transduction can occur in different types of bacteria like- Salmonella,
Escherichia, etc. While specialized transduction occurs occasionally in the
lysogenic lifecycle of temperate bacteriophage.
As is with the other methods of the genetic
transfer process, is essential to cell speciation, adaptation, and cellular
evolution. It can assist in transferring DNA to another organism to increase
virulence and improve the efficiency of metabolic reactions. This process is very important as it can
introduce a major, new defence function called antibiotic resistance.
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