# Explain how the structure of channel proteins and carrier proteins differs and how this relates to their different roles in membrane transport.

> IB DP Biology Standard Level (2023 syllabus) — B2.1 Membranes and membrane transport · Explain · 4 marks

## Mark scheme (4 marks)

1. Channel proteins form a continuous, hydrophilic pore/tunnel through the membrane
2. Channel proteins allow facilitated diffusion of ions or small polar molecules down their concentration gradient without a conformational change
3. Carrier proteins have a binding site that binds a specific solute, causing a conformational change (change in shape) that moves the solute across the membrane
4. Carrier proteins can facilitate active transport (using ATP) as well as facilitated diffusion, whereas channel proteins only allow passive transport

## Key terms

- [channel protein](https://www.gradenine.co.uk/glossary/channel-protein)
- [carrier protein](https://www.gradenine.co.uk/glossary/carrier-protein)

## Related

- [Revision notes for IB DP Biology Standard 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-structure-of-channel-21320bfe) · Published by Druglandscape Ltd.