# Explain how the structural features of the smooth endoplasmic reticulum (SER) are related to its functions in a hepatocyte (liver cell).

> IB DP Biology Higher Level (2023 syllabus) — B2.2 Organelles and compartmentalisation · Explain · 4 marks

## Mark scheme (4 marks)

1. The SER is an extensive network of membranous tubules, providing a large surface area for enzyme-mediated reactions such as detoxification of lipid-soluble drugs and toxins.
2. Detoxification enzymes (e.g. cytochrome P450) are embedded within the SER membrane, allowing lipid-soluble compounds to be converted into water-soluble forms for excretion.
3. The SER forms a closed, continuous membrane compartment that sequesters toxic intermediates, protecting the rest of the cytoplasm from damage during detoxification.
4. The SER also stores and releases calcium ions (Ca²⁺) by means of membrane-embedded Ca²⁺-ATPase pumps and Ca²⁺ channels, enabling regulation of cellular signalling and metabolic processes in the hepatocyte.

## Key terms

- [smooth endoplasmic reticulum (SER)](https://www.gradenine.co.uk/glossary/smooth-endoplasmic-reticulum-ser)
- [hepatocyte](https://www.gradenine.co.uk/glossary/hepatocyte)

## 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-structural-features-of-85059d7d) · Published by Druglandscape Ltd.