Functions of pili in Bacteria
This is clearly beneficial to the F-plasmid, since its genes get replicated, but why is it useful to the bacteria?
The F-plasmid often contains useful genes that deal with stressful situations that have recently arisen, for will
spread this resistance to other bacteria. Since the F-plasmid can integrate into the host's chromosomal DNA it
can, upon leaving, take away copies of host genes with it, these genes may be of use to the recipient cell. This
conjugation process is the closest that bacteria get to having sex - bacteria have no gender and they do not
reproduce sexually, but they can exchange and mix-up their genetic material in this way.
they are small mobile, self-replicating genetic elements. Some plasmids can exist in multiple copies within a
single cell, but only a single F-plasmid may occur in each host bacterial cell.The function of pili in export and importAnother way that bacteria can take on-board new genetic information is by taking up bits of DNA from their
environment - DNA released by dead or damage cells nearby. This DNA can then be incorporated into the cell's
own DNA and the whole process is called (natural) transformation. Pili (of type IV) have been implicated in this
process. These pili appear to bind to DNA and then retract, bringing the DNA into the cell. They have hollow
channels and the possibility remains that DNA is transported through the pilus channel. Other protein systems,
apart from pili, may also accomplish DNA uptake. (In artificial transformation, bacteria that do not naturally take
up DNA are made to do so, for example by applying electric shocks which open up transient channels in the cell
envelope through which external DNA can enter). Not all bacteria can take up DNA, and those that can are
described as competent.
Source: cronodon.com
