# Explain how the process of splicing of pre-mRNA contributes to proteome diversity in eukaryotes.

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

## Mark scheme (4 marks)

1. Pre-mRNA contains both introns (non-coding sequences) and exons (coding sequences) that must be processed before translation.
2. Introns are removed and exons are joined together during splicing to form mature mRNA.
3. Alternative splicing allows different combinations of exons to be included in the mature mRNA from the same pre-mRNA / gene.
4. This produces multiple different polypeptides / proteins from a single gene, increasing the size of the proteome beyond what the number of genes alone would allow.

## Key terms

- [pre-mRNA](https://www.gradenine.co.uk/glossary/pre-mrna)
- [splicing](https://www.gradenine.co.uk/glossary/splicing)
- [proteome](https://www.gradenine.co.uk/glossary/proteome)

## 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-process-of-splicing-a7119d7a) · Published by Druglandscape Ltd.