# Explain how the structure of the cell wall in prokaryotes differs from that in plant cells, and outline why this difference is clinically significant.

> IB DP Biology Higher Level (2023 syllabus) — A2.2 Cell structure · Explain · 4 marks

## Mark scheme (4 marks)

1. Prokaryote cell walls are composed of peptidoglycan (murein), a polymer of sugars cross-linked by short peptide chains.
2. Plant cell walls are composed of cellulose, a polysaccharide of β-1,4-linked glucose monomers, with no peptide components.
3. Antibiotics such as penicillin target peptidoglycan synthesis / inhibit enzymes that cross-link the peptide chains, disrupting cell wall formation in bacteria.
4. Because human (animal) cells lack a cell wall entirely, and plant cells lack peptidoglycan, these antibiotics selectively kill bacteria without harming host cells, providing selective toxicity.

## Key terms

- [cell wall](https://www.gradenine.co.uk/glossary/cell-wall)

## 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-the-structure-of-the-565d66b6) · Published by Druglandscape Ltd.