Final answer:
The F-plasmid in E.coli is an example of a conjugative plasmid, which enables DNA transfer between bacterial cells through a process called conjugation, using a structure known as the F pilus.
Step-by-step explanation:
The F-plasmid, also known as the fertility factor, is an example of a conjugative plasmid in E.coli. This type of plasmid facilitates DNA transfer between cells via a process called conjugation. Bacteria that contain the F-plasmid, designated as F+ cells or donor cells, can form a special structure called the F pilus (or F pili), which attaches to F- (recipient) cells, allowing the transfer of genetic material. Once contact is established, a mating bridge is formed, and a single-stranded copy of the F-plasmid is transferred to the F- cell, which then becomes an F+ cell itself, capable of conjugating with other F- cells.
The existence of the F plasmid enables E.coli cells to share and spread genetic information rapidly through a bacterial population. Such transfer can include not only the F-plasmid itself but occasionally chromosomal DNA as well, in cases where the F-plasmid has integrated into the bacterial chromosome to create an Hfr (High-frequency recombination) cell. Thus, the F-plasmid plays a critical role in genetic variation and adaptation in bacterial communities.