Final answer:
The three main methods of gene transfer in bacteria are transformation, transduction, and conjugation, each involving different mechanisms for DNA exchange. Therefore, all the answers are correct.
Step-by-step explanation:
The three primary mechanisms by which prokaryotes can exchange DNA are:
- Transformation: In this process, a bacterial cell takes up n4ked DNA directly from its environment. This DNA may then remain separate, existing as a plasmid, or it can be incorporated into the bacterial host genome.
- Transduction: During transduction, a virus, specifically a bacteriophage, transfers genes by injecting DNA into a bacterial cell. This DNA can be a combination of viral DNA and DNA from a previously infected bacterium.
- Conjugation: This method involves the direct transfer of DNA from one bacterium to another using a hollow tube, or pilus. After a sex pilus brings the two bacteria close enough, a mating bridge forms, allowing DNA to pass through.
Among these methods, conjugation is particularly notable for being a natural mechanism responsible for the spread of antibiotic resistance genes within bacterial populations.