Resistance to an antibiotic can be transferred from one organism to another through which mechanism?

The transfer of antibiotic resistance between organisms is commonly facilitated by extrachromosomal plasmids. Plasmids are small, circular DNA molecules that exist independently of the chromosomal DNA and can carry genes, including those that confer resistance to antibiotics. These plasmids can be easily transferred between bacteria through processes like conjugation, where direct contact between two bacteria allows the transfer of plasmid DNA.

This mechanism of resistance transfer is significant because it enables even genetically diverse bacteria to acquire the ability to resist certain antibiotics quickly, leading to increased challenges in treating infections. The extrachromosomal nature of plasmids allows these resistance traits to spread rapidly within populations, contributing to the public health issue of antibiotic resistance.

Mutational resistance involves changes in the bacterial DNA that result in resistance, but this process typically occurs within a single organism and does not inherently involve transfer between bacteria. Chromosomal transformation refers to the uptake of free DNA from the environment into a bacterial cell, which can also lead to changes in resistance but is less common than plasmid-mediated transfer. Natural selection is a broader concept describing how certain traits become more or less common within a population over time; it does not directly describe the mechanism by which resistance is transferred.