Question

Sex factor of bacteria is
A) Replicon
B) F-factor
C) Sex pilli
D) sRNA

Answer 1

Hint: Though technically bacteria do not have genders, they do undergo a process known as conjugation during which one bacterial cell can share a copy of extrachromosomal DNA with a second bacterial cell. DNA is transferred from the donor to the recipient bacterium.

Complete Answer:
- A replicon is a part of a eukaryotic genome. It essentially consists of several genes that undergo bi-directional duplication under the control of a single point of origin of replication, or ori site. The replication will stop at the points where the replication fork meets the ori on the opposite strand of DNA. This is not connected to bacterial conjugation, option A is incorrect.
- The F-factor or fertility factor is a bacterial plasmid. During conjugation, the plasmid opens up and starts duplicating. One of the two new plasmids produced is directly sent into the second bacterial cell where, once replication is over, it re-circularises so that each of the bacterial cells involved in the conjugation have their own copy of the F-factor. Option B is the correct answer.
- During bacterial conjugation, in order to be able to transfer DNA from one cell to the other, the bacteria form an extension of their cell membranes that join together to form a hollow tube. This hollow tube or sex pillus is the way the F-factor is transmitted. Option C is incorrect.
- sRNAs are small bacterial RNA molecules that help regulate bacterial growth during encounters with stressful environments. They are involved in regulation of gene expression. Option D is incorrect.

Hence the correct answer is option B.

Note: The F-factor or F-plasmid is useful to transfer genes that help in bacterial survival. These include genes for antibiotic resistance. Bacteria that have the plasmid are F+, and those without are F-.