# Explain how the wobble hypothesis accounts for the fact that the number of tRNA molecules required for translation is less than the number of sense codons in the genetic code.

> IB DP Biology Higher Level (2023 syllabus) — D1.2 Protein synthesis · Explain · 4 marks

## Mark scheme (4 marks)

1. The genetic code contains 61 sense (non-stop) codons but far fewer tRNA anticodon types are needed to decode them.
2. The wobble position is the third (3′) base of the codon / first (5′) base of the anticodon, where base-pairing rules are relaxed.
3. One tRNA anticodon can recognise more than one codon because the base at the wobble position can form hydrogen bonds with more than one complementary base.
4. This means that synonymous codons (codons coding for the same amino acid that differ only at the third position) can be read by the same tRNA, reducing the total number of distinct tRNA molecules needed.

## Key terms

- [wobble hypothesis](https://www.gradenine.co.uk/glossary/wobble-hypothesis)
- [sense codon](https://www.gradenine.co.uk/glossary/sense-codon)

## 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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-wobble-hypothesis-accounts-3ca3ef9d) · Published by Druglandscape Ltd.