mercredi 16 mars 2011

Bacterial conjugation



Bacterial conjugation, cutaway artwork. Conjugation is a form of sexual reproduction in which pieces of DNA (deoxyribonucleic acid) called plasmids (circular, shown in the cutaway portions) are transferred between bacteria through a structure called a pilus.

Antibiotic resistance

Artwork of bacterial cells becoming resistant to antibiotics. This resistance is acquired from a donor cell's plasmid (circular unit of deoxyribonucleic acid, DNA), which has resistance seen at upper left (red/yellow, red is resistance). Viral transmission involves a virus (pink, lower left) obtaining a resistant gene, and passing it to a bacterial cell that incorporates it into its plasmid. Bacterial cells also acquire segments of DNA released from dead cells (upper left). Mutations (not seen) may also occur, which may be antibiotic resistant and thus allow the bacteria to survive and reproduce.