# Explain why a molecule of glycine (an amino acid with the molecular formula C₂H₅NO₂) can be classified as belonging to two different functional group classes simultaneously, and state the name of each functional group present.

> IB DP Chemistry Standard Level (2023 syllabus) — S3.2 Functional groups: classification of organic compounds · Explain · 4 marks

> Glycine is the simplest amino acid and is found in many proteins. Its molecular formula is C₂H₅NO₂.

## Mark scheme (4 marks)

1. Glycine contains an amine (–NH₂) functional group
2. Glycine contains a carboxylic acid (–COOH) functional group
3. Because each functional group is independently present in the same molecule, it can be classified as both an amine and a carboxylic acid
4. The presence of two functional groups in one molecule means glycine belongs to the class of compounds called amino acids, which are defined by having both an amine and a carboxylic acid group

## Key terms

- [functional group](https://www.gradenine.co.uk/glossary/functional-group)
- [amino acid](https://www.gradenine.co.uk/glossary/amino-acid)

## Related

- [Revision notes for IB DP Chemistry Standard 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-why-a-molecule-of-glycine-b756a75e) · Published by Druglandscape Ltd.