In AP Bio, transposition is the movement of DNA segments (transposable elements) within and between DNA molecules. It's one of the ways prokaryotes acquire new genetic information, increasing genetic variation that natural selection can act on (EK 6.7.C.1).
Transposition is when chunks of DNA, called transposable elements (or "jumping genes"), physically move from one spot to another. They can hop within a single DNA molecule or jump between molecules, like from a plasmid into the bacterial chromosome. Because these segments can carry genes with them, transposition shuffles the genetic deck and creates variation.
In the CED, transposition shows up under EK 6.7.C.1 as one of four ways prokaryotes pick up new genetic information. The other three are transformation (uptake of naked DNA), transduction (viral transfer), and conjugation (cell-to-cell transfer through a physical bridge). Transposition is the odd one out because the DNA isn't coming from outside the cell, it's rearranging DNA that's already inside.
Transposition lives in Unit 6 (Gene Expression and Regulation), specifically topic 6.7 Mutations. It supports learning objective [AP Bio 6.7.C], which asks you to explain how alterations in DNA sequences contribute to variation that natural selection can act on. The big-picture theme is evolution: anything that generates genetic variation feeds the raw material for natural selection. Transposition matters most when you connect it to antibiotic resistance, where a transposon carrying a resistance gene jumps into a new location and spreads that survival advantage through a population under selective pressure.
Keep studying AP® Biology Unit 6
Conjugation, Transformation, and Transduction (Unit 6)
These are the other three mechanisms in EK 6.7.C.1 that increase prokaryotic genetic variation. The clean distinction: transposition rearranges DNA already inside the cell, while the other three bring DNA in from outside (naked DNA, a virus, or a neighboring cell).
Mutations as a Source of Variation (Unit 6)
Topic 6.7 frames mutations as the source of genetic variation (EK 6.7.B.1). Transposition is essentially a large-scale version of this. When a transposon lands in the middle of a gene, it can disrupt it, acting a lot like a frameshift or insertion mutation.
Natural Selection and Antibiotic Resistance (Units 6-7)
A transposon carrying a resistance gene that jumps into a chromosome gets passed on more reliably. Under antibiotic pressure, the cells that have it survive and reproduce, so transposition feeds directly into natural selection (the link 6.7.C draws to evolution in Unit 7).
Transposition shows up most often in multiple-choice questions that ask you to match a mechanism to its description. A classic stem describes a process where "DNA segments move within and between molecules" and expects you to pick transposition over transformation, transduction, or conjugation. The trickiest stems describe a transposon carrying an antibiotic resistance gene jumping from a plasmid into the bacterial chromosome under antibiotic pressure, then ask you to explain why this increases genetic variation and how natural selection acts on it. No released FRQ has used the word transposition verbatim, but it fits the kind of variation-and-selection reasoning that free-response evolution questions reward. Your job is to recognize the mechanism by its description and connect it to increased genetic variation.
Both increase genetic variation in prokaryotes, but they're not the same. Conjugation transfers DNA from one cell to another through a physical bridge (pilus). Transposition moves DNA segments within a single cell's genome, like a transposon hopping from a plasmid to the chromosome. If two bacteria touch and pass genes, that's conjugation; if a segment jumps between molecules inside one cell, that's transposition.
Transposition is the movement of DNA segments (transposable elements) within and between DNA molecules inside a cell.
It's one of four mechanisms in EK 6.7.C.1 that increase prokaryotic genetic variation, alongside transformation, transduction, and conjugation.
Unlike the other three, transposition rearranges DNA already inside the cell rather than bringing new DNA in from outside.
Transposition matters for evolution because the variation it creates can be acted on by natural selection (learning objective AP Bio 6.7.C).
A common exam scenario is a transposon carrying an antibiotic resistance gene jumping into the chromosome, which spreads resistance under selective pressure.
Transposition is the movement of DNA segments, called transposable elements or jumping genes, within and between DNA molecules. It's listed in EK 6.7.C.1 as one of the ways prokaryotes increase genetic variation.
No. Transposition rearranges DNA that's already inside the cell. That's what separates it from transformation (uptake of naked DNA), transduction (viral transfer), and conjugation (cell-to-cell transfer).
Conjugation transfers DNA from one bacterium to another through a physical bridge between two cells. Transposition moves DNA segments within a single cell's genome, such as a transposon jumping from a plasmid to the chromosome. The key difference is whether the DNA crosses between cells.
Transposition creates genetic variation, and variation is the raw material natural selection acts on (AP Bio 6.7.C). For example, when a transposon carrying an antibiotic resistance gene jumps into a chromosome, cells with it survive and reproduce under antibiotic pressure.
Yes, it appears in Unit 6 under topic 6.7 Mutations. Expect multiple-choice questions that describe a process moving DNA within and between molecules and ask you to identify it as transposition, often in an antibiotic resistance context.
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