Transposons(Tn)-Transposons are transposable genetic elements that carry one or more other genes in addition to those which are essential for transposition o Nomenclature- Transposons are given the designation Tn followed by a number Structure- The structure of a transposon is similar to that of an insertion sequence, The extra genes are located between the terminal repeated sequences. In some instances (composite transposons)the terminal repeated sequences are actually insertion sequences Importance- Many antibiotic resistance genes are located on transposons Since transposons can jump from one DNa molecule to another, these antibiotic resistance transposons are a major factor in the development of plasmids which can confer multiple drug resistance on a bacterium harboring such a plasmid. These multiple drug resistance plasmids have become a major medical problem because the indiscriminate use of antibiotics have provided a selective advantage for bacteria harboring these plasmids. Is Resistance Gene(s) Is IS Resistance Gene(s) ISTransposons (Tn) - Transposons are transposable genetic elements that carry one or more other genes in addition to those which are essential for transposition. • Nomenclature - Transposons are given the designation Tn followed by a number. • Structure - The structure of a transposon is similar to that of an insertion sequence. The extra genes are located between the terminal repeated sequences. In some instances (composite transposons) the terminal repeated sequences are actually insertion sequences. • Importance - Many antibiotic resistance genes are located on transposons. Since transposons can jump from one DNA molecule to another, these antibiotic resistance transposons are a major factor in the development of plasmids which can confer multiple drug resistance on a bacterium harboring such a plasmid. These multiple drug resistance plasmids have become a major medical problem because the indiscriminate use of antibiotics have provided a selective advantage for bacteria harboring these plasmids