Definition
Transposons are mobile genetic elements that can move within the genome, from one location to another, or between chromosomes and plasmids.
Types of Transposons
Insertion Sequences (IS Elements)
The simplest transposons, containing only genes for transposase (an enzyme that catalyzes movement).
Example: IS1 in E. coli.
Composite Transposons
Contain additional genes (e.g., antibiotic resistance genes) between two insertion sequences.
Example: Tn10 (carries tetracycline resistance).
Replicative Transposons
Create a copy of themselves and insert it elsewhere in the genome.
Conjugative Transposons
Can move between bacteria through conjugation and spread resistance genes.
Mechanism of Transposition
The transposase enzyme recognizes specific sequences and cuts the transposon out of its original location.
The transposon is then inserted into a new location within the genome or a plasmid.
Significance
Cause mutations by disrupting genes when they insert into new locations.
Contribute to genetic variation and evolution.
Help in the spread of antibiotic resistance genes among bacteria.
