Summary
Direct transfer of DNA, such as a plasmid, between bacterial cells through a pilus.
In depth
The F plasmid donor extends a pilus, a relaxase nicks the plasmid and a single strand is transferred; both cells end up with a complete copy. Hfr cells integrate F into the chromosome and transfer chromosomal genes.
It spreads antibiotic resistance among species.
Requires cell contact. F plasmid encodes transfer genes. Hfr transfer is time-dependent, used to map genes.
Common mistake: conjugation in bacteria is not sexual reproduction since no new individuals are produced.
Lederberg and Tatum discovered conjugation in 1946. F+ cells carry the plasmid and donate to F- cells, making them F+. Hfr cells have the plasmid in the chromosome and transfer chromosomal genes starting from a fixed point, so the time of entry can map genes (interrupted mating experiments), with the whole chromosome rarely transferred because the bridge breaks. F-prime plasmids pick up chromosomal genes.
Conjugative plasmids move between species and even to yeast and plants, which is how multidrug resistance spreads in hospitals. Contact between cells is by pili, and the transfer machinery is a type IV secretion system.
Key idea: it is the bacterial equivalent of a one-way sexual exchange, but it is not reproduction.
Frequently asked questions
What is Conjugation?
Direct transfer of DNA, such as a plasmid, between bacterial cells through a pilus.
Which area of biology covers Conjugation, and how advanced is it?
Conjugation is one of the 54 topics in Microbiology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Antibiotics, Horizontal Resistance Spread, Plasmids.
Can you give an example of Conjugation?
Lederberg and Tatum discovered it in 1946.
What should I learn before Conjugation?
Work through the Beginner topics in Microbiology first, such as Microorganisms, Bacteria, Archaea, then return to Conjugation. Intermediate topics assume the Beginner vocabulary.
What topics are related to Conjugation?
The closest topics to Conjugation are Antibiotics, Horizontal Resistance Spread, Plasmids, Bacterial Genetics. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Conjugation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Conjugation. To practise the whole of Microbiology, use the Microbiology quiz.
How is Conjugation different from Antibiotics?
Conjugation: Direct transfer of DNA, such as a plasmid, between bacterial cells through a pilus. Antibiotics: Drugs that kill or inhibit bacteria, such as penicillin, which blocks cell wall synthesis. Read both side by side and note what each one explains.
What is a common mistake about Conjugation?
Conjugation in bacteria is not sexual reproduction since no new individuals are produced.
How should I study Conjugation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Antibiotics and explain the difference aloud. Finally, take the Microbiology quiz and come back to this page for any question you miss.