Navigation Links
Bacterial conjugation


Bacterial conjugation is the often regarded as the bacterial equivalent of sexual reproduction or mating; however it is not actually sexual as it does not involve the fusing of gametes and the creation of a zygote, it is merely the exchange of genetic information. In order to perform conjugation, one of the bacteria has to carry an F-plasmid, the other one must not.

The F-plasmid (also called F-factor) is an episome (a plasmid that can integrate itself into the bacterial chromosome by genetic recombination) of about 100 kb (kilo base pairs) length. It carries its own origin of replication, called oriV. There can only be one copy of the F-plasmid in a bacterium (which is then called F-positive), either free or integrated.

Among other genetic information, the F-plasmid carries a tra and a trb locus, which together are about 33 kb long and consist of about 40 genes. The tra locus includes the pilin gene and controlling genes, which together form pili on the cell surface, polymeric proteins that can attach themselves to the surface of F-negative bacteria and initiate the mating. The pili themselves do not seem to be the structures through which the actual exchange of DNA takes place; rather, some proteins coded in the tra or trb loci seem to open a channel between the bacteria.

The transfer of DNA always runs from the F-positive towards the F-negative bacterium.

  • If the F-plasmid is free, a nick is produced in one of the circular DNA strands of the plasmid. Then, the single-stranded DNA of the nicked strand is inserted into the recipiane bacterium (5'-end first). The now single-stranded plasmid is filled up with a complementary strand by a rolling cycle mechanism.
  • If the F-plasmid is integrated, the transferred DNA consists of the F-plasmid sequence plus an amount of chomosomal DNA from the donor bacterium. The amount of chromosomal DNA that is transferred depends on how long the bacteria hold contact; the transfer of the whole bacterial chromosome would take about 100 minutes. The transferred DNA can be integrated into the recipients DNA by recombination. Bacteria with an integrated F-plasmid do recombine unusually often, which is why they are also called Hfr-(high frequency recombination-)strains.

See also


'"/>


(Date:8/5/2015)... Aug. 5, 2015 The biosensors market is ... applications, penetration into newer sectors, and development of devices ... biosensors space has seen the entry of multiple participants ... far. (Photo - http://photos.prnewswire.com/prnh/20150805/255570 ) ... Analysis of the Global Biosensors Market ( http://www.frost.com/nee9 ...
(Date:8/4/2015)... 4, 2015  AMRI (NASDAQ: AMRI ) today reported financial ... Highlights: , Second quarter contract revenue of ... , Adjusted contract margins of 26 ... including a $0.05 decrease in EPS from royalties in the current ... "We are very pleased to present another strong ...
(Date:7/31/2015)... Kina, 31. juli 2015 Den 10. internationale ... af BGI fra den 22. - 25. oktober i ... fejrer sin 10-års fødselsdag i år. Siden starten i ... årlige møder på ,omik,-feltet, og er en af de ... ICG-10 fokuserer på nylige gennembrud og fremskridt inden ...
Breaking Biology News(10 mins):Innovative Biosensors Incite Use in Non-Traditional Applications 2Innovative Biosensors Incite Use in Non-Traditional Applications 3Innovative Biosensors Incite Use in Non-Traditional Applications 4AMRI Announces Second Quarter 2015 Results 2AMRI Announces Second Quarter 2015 Results 3AMRI Announces Second Quarter 2015 Results 4AMRI Announces Second Quarter 2015 Results 5AMRI Announces Second Quarter 2015 Results 6AMRI Announces Second Quarter 2015 Results 7AMRI Announces Second Quarter 2015 Results 8AMRI Announces Second Quarter 2015 Results 9AMRI Announces Second Quarter 2015 Results 10AMRI Announces Second Quarter 2015 Results 11AMRI Announces Second Quarter 2015 Results 12AMRI Announces Second Quarter 2015 Results 13AMRI Announces Second Quarter 2015 Results 14AMRI Announces Second Quarter 2015 Results 15AMRI Announces Second Quarter 2015 Results 16AMRI Announces Second Quarter 2015 Results 17AMRI Announces Second Quarter 2015 Results 18AMRI Announces Second Quarter 2015 Results 19AMRI Announces Second Quarter 2015 Results 20AMRI Announces Second Quarter 2015 Results 21AMRI Announces Second Quarter 2015 Results 22AMRI Announces Second Quarter 2015 Results 23AMRI Announces Second Quarter 2015 Results 24Den 10. internationale konference om Genomics (ICG-10) åbner i oktober 2
... structure mapping and thermodynamics is introduced for RNA pseudoknot ... the context of the biological folding direction (5 to ... information about the flexibility of the RNA. Mapping methods ... and add important 3D structural considerations. The model suggests ...
... National Institute of Allergy and Infectious Diseases (NIAID) of the ... Mary Woodard Lasker Award for Public Service for his role ... and biodefense. The award will be presented on Friday, September ... Dr. Fauci is honored for his role in helping develop ...
... America (ESA), in cooperation with the American Phytopathological ... Small Grain Insects, the latest in ESAs Insect ... the biology and management of arthropod pests and ... with expertise on specific pest groups have provided ...
Cached Biology News:Anthony S. Fauci awarded Lasker Award for Public Service 2Anthony S. Fauci awarded Lasker Award for Public Service 3Anthony S. Fauci awarded Lasker Award for Public Service 4Handbook of small grain insects available now 2
Other biology definitionOther Tags