Recombination in Bacteria - Transformation, Transduction and Conjugation

Genetic recombination in bacteria: Transformation, Transduction and Conjugation
Evolution of sexual reproduction is one of the major milestones in the history of life that actually fuelled this amazing diversity. But think of bacteria, simple in structure, no true sexual reproduction, still present everywhere in the planet from our intestine to deep thermal vents even in extreme temperatures of hot sulphur springs (Archae bacteria). The possible answer might be the mutation occurring in bacteria that makes its genome updated very often. Sexual reproduction involves formation of gametes by meiosis and union of gametes or fertilization to form the first cell, zygote. In bacteria, all these processes are absent. Generally, genetic variation occurs through mutation and by gene transfer methods that we are going to discuss in this post.

What are merozygotes?
In bacteria, true zygotes are not formed; instead we use a term merozygote. Merozygotes are partial diploids where the complete transfer of genetic material from donor to recipient has not occurred.

Mechanisms of gene transfer in bacteria
Bacterial gene transfer is achieved by three mechanisms. In all the mechanisms, a part of DNA is transferred from one mature bacterial cell to another.  
Bacterial Conjugation
Bacterial Conjugation 
  • Transformation: is the uptake of DNA fragments (originates from one bacterial cell) from the surroundings by a bacterial cell. Later this gets integrated into the bacterial genome. Read more
  • Transduction: gene transfer in bacteria mediated by viruses (virus mediated gene transfer). Read more
  • Conjugation: is the unidirectional transfer of genetic materials from a donor bacterium to a recipient through cell to cell contact via sex pili (conjugation tube). Read more
The above definitions are the key in understanding the concept. Let us move into the details of each process.
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