What do we call a DNA segment that carries one or more genes flanked at both ends by inverted repeat sequences?

Introduction / Context:
Mobile genetic elements vary by complexity. Insertion sequences are minimal, while transposons often include additional “cargo” genes and are bounded by inverted repeats that serve as recognition sites for transposition enzymes.

Given Data / Assumptions:

• Feature set: genes in the center; inverted repeats at both ends.
• Function: mobility via transposase/integrase activity.
• Contrast with plasmids: typically circular and not defined by terminal inverted repeats.

Concept / Approach:
A transposon is defined by its ability to move and by the presence of terminal inverted repeats that the transposase recognizes to cut and insert the element. Cargo genes may encode resistance, toxins, or metabolism, differentiating it from a bare IS element that usually carries only transposase.

Step-by-Step Solution:
Match structural description to mobile element taxonomy.Recognize that “genes + inverted repeats” describes a transposon.Exclude plasmids (no terminal inverted repeats required) and IS (typically minimal cargo).

Verification / Alternative check:
Genome annotations label such structures as Tn elements (for example, Tn3), with IRL/IRR termini.

Why Other Options Are Wrong:

• Plasmid: may carry many genes but lacks defining inverted-repeat termini.
• IS: usually only transposase without extra cargo.
• Operon: transcriptional unit, not a mobile element.

Common Pitfalls:
Using “IS” as a catch-all; remember cargo distinguishes transposons from IS elements.

Final Answer:
Transposon