# Explain how transposons contribute to genetic variation within a population.

> IB DP Biology Higher Level (2023 syllabus) — D1.3 Mutations and gene editing (HL only) · Explain · 4 marks

> Transposons, sometimes called 'jumping genes', are DNA sequences capable of changing their position within a genome. Barbara McClintock first described them in maize in the 1940s, though their significance was not widely recognised until decades later.

## Mark scheme (4 marks)

1. Transposons can insert into new positions within the genome (transposition), disrupting or altering the expression of genes at the insertion site.
2. Insertion of a transposon into a coding sequence or promoter region can cause a loss-of-function mutation, generating a new allele and therefore new genetic variation.
3. Transposons can cause chromosomal rearrangements (deletions, inversions, or duplications) when transposition events occur between non-homologous sites, further increasing genomic and phenotypic variation.
4. Variation generated by transposon activity is heritable if it occurs in germline cells, providing raw material for natural selection to act upon within a population.

## Key terms

- [transposon](https://www.gradenine.co.uk/glossary/transposon)
- [genetic variation](https://www.gradenine.co.uk/glossary/genetic-variation)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-transposons-contribute-to-genetic-7078672a) · Published by Druglandscape Ltd.