Question

A substantial amount of genetic information is exchanged between bacterial genomes through the process of horizontal transfer. Explain the different mechanisms of how genetic information is transferred in bacteria, explain the relevance of each mechanism and give examples from the real world of horizontally transferred genes.

Answer 1

Horizontal gene transfer is the process of transfer of genetic material between unrelated bacterial or microorganisms. HGT is also referred to as lateral gene transfer and is the non sexual movement of genetic content. HGT allows the acquisition of new genes from different bacterial species. Therefore, a substantial amount of genetic material is transferred in bacterial genomes via the process of HGT. There are 3 main mechanisms of HGT:

1. Transformation

2. Transduction

3. Conjugation

(A) Transformation: uptake and incorporation of naked or small fragments of DNA from a donor bacterium to a competent recipient bacterium. The donor DNA is integrated into the recipient bacterial genome by means of homologous recombination. The prcoess of transformation is widely used in DNA cloning experiments.

(B) Transduction: The process of transduction deals with transfer of DNA from one bacteria to another by means of bacteriophages. It makes use of viruses that specifically infects the bacterial species for transferring the genetic material. It is commonly used by molecular biologists to stably introduce and transfer foreign gene into bacterial cell.

(C) conjugation: Conjugation predominantly involves tranfer of DNA fragments directly from one bacterial cell to another through cell contact mainly by means of sex pilus.  Example of DNA transferred by conjugation often involves plasmid for providing antibiotic resistance.