Transposons (Jumping Genes): General characteristics and composition

Transposons are pieces of DNA that move readily from one site to another, either within or between the DNA’s of bacteria, plasmids, and bacteriophage.

They can code for Drug resistance enzymes, toxins, or a variety of metabolic enzymes.
They either cause mutations in the gene into which they insert or alter the expression of nearby genes.

Transposons are not capable of independent replication; they replicate as part of the recipient DNA.
eg. A plasmid can contain several transposons carrying drug resistance genes.

Insertion sequences are a type of transposons that has fewer bases.

Domains of Transposons:

Transposons have four identifiable domains.

  1. Inverted repeats (IR): Involved in the integration of the transposons into the recipient DNA.
  2. Transposase gene: It codes of the enzyme that mediates excision and integration process.
  3. Repressor gene: It regulates the synthesis of both the transposase and gene product of fourth domain
  4. Fourth domain codes for an enzyme which mediates antiboitic resistance.