Question

A composite transposon integrated in a circular plasmid occasionally transposes the DNA comprising the original plasmid rather than the transposon’s central region. Explain how this is possible.

Short answer

The composite transposons contain two IS elements flanking the sequence. It can cause the transposition of the original plasmid along with the central region of the transposon.

Step-by-step solution

Components in addition to DNA

The fundamental genetic substance is deoxyribonucleic acid (DNA). It contains all of the information about a person's ancestors that will be passed down from generation to generation. Other components, in addition to DNA, include genetic material. Plasmids are tiny DNA molecules that coexist alongside chromosomal DNA. It has a round shape to it. This plasmid DNA has the ability to multiply on its own.

A transposon is a tiny DNA molecule that inserts itself into the genome at a different location. A mutation is caused or reversed by this shift in location. Simple or compound transposons are possible. A simple transposon contains insertion sequence made up of short, repetitive sequences flanking the gene's coding region.

Explanation of the possibility

Simple transposons and composite transposons are quite similar. They are, however, flanked by two insertion sequence (IS) elements rather than one. Most of the time, these transposons carry antibiotic resistance. Rather than being transposed separately, both insertion sequence components are transposed as a single unit.

Therefore, the antibiotic-containing region lies in the centrer, bordered by two IS elements. Occasionally, instead of transferring the core sections, these transposons transpose the DNA of the original plasmid. Each insertion sequence can be transferred independently, or segments can be transposed as a whole if the transposition occurs on outer inverted repeats, which can include the segment of the original plasmid