Antibiotic resistant bacteria is a big concern now a day due to the use of excessive and improper use of antibiotics. It is very common for people to star taking an antibiotic and stop the regimen as soon as the symptoms are gone. With this practice, bacteria that were not killed by the antibiotic but were exposed, are capable of becoming immune to it. This immunity or resistance can be passed on from bacteria to bacteria through the exchange of their genetic material using some of the methods of horizontal gene transfer. As a result, the resistance acquired by one pathogen can be passed to other pathogens.
2) Describe conjugation in prokaryotes.
Conjugation in prokaryotes is the method used to transfer genetic materials from alive donor cells, and is mediated by pili. Pili are proteinaceous tubes outspreading from the surface of a cell. The cells that are the donor during conjugation have an F Plasmid (fertility plasmid), which is a circular, small, extrachromosomal molecule of DNA. Donor with cells are referred as F+ and recipient as F-. This process involves the following steps: 1) The pilus connects the donor cell (F+) and the recipient cell (F-). 2) Only a single strand of the F plasmid DNA is transfer to the recipient. 3) The recipient (F-) becomes an (F+) by synthesizing a complementary strand of the F plasmid DNA. 4) A complementary plasmid DNA strand is also synthesizes by the donor cell. It is possible that the F plasmid formed in the new (F+) cell does not remain in the cytosol, and instead it is combined in the cellular chromosome at a specific DNA sequence. If this is the case, this cell is known as a Hfr (high frequency of recombination) cell. After the F plasmid is integrated in Hfr cell, this cell has now the capacity of joining with an (F-) cell and transfer its DNA. The F+ cell transfer part of the F plasmid, and some of its own chromosome. In most case, due to movement of the cells the connection breaks before the entire chromosome is transferred. As a result the recipient remains being F- cell, but now has some chromosomal genes from the donor. 3) Describe horizontal gene transfer in prokaryotes. Explain transformation and transduction in depth. Horizontal gene transfer in prokaryotes is an erratic occurrence because it is seen only in 1% of the population. It allows prokaryotes to gain genes from other microorganisms of the same generation. During this process, the cell that gives part of its genome is called, a donor cell; and the receiver, a recipient cell, can be from a different species. The recipient cell becomes a recombinant cell as it incorporate the donor’s DNA into its own. In transformation, DNA is taking up from the environment by the recipient cell. …show more content…
In some cases, the DNA comes from a dead organism. When the cells have the ability to take up DNA from their environment, they are known to be competent. In a competent cell, the cell wall and cytoplasmic membrane are altered to allow the DNA to go into the cell. This process can happen naturally in the environment or it artificially by manipulating the temperature and salt concentration of the medium. Since competent cells can accept DNA from any donor genome, competence and transformation are essential tools in recombinant DNA technology, known as genetic