# Explain how the peptide bond is formed during translation and outline the chemical nature of this bond.

> IB DP Biology Higher Level (2023 syllabus) — B1.2 Proteins · Explain · 4 marks

## Mark scheme (4 marks)

1. The ribosome catalyses the formation of the peptide bond between two amino acids / between the amino group of one amino acid and the carboxyl group of another.
2. The reaction is a condensation reaction, releasing a molecule of water.
3. The peptide bond is a covalent bond between the carbon of one amino acid's carbonyl group and the nitrogen of the next amino acid's amine group (–CO–NH–).
4. The peptide bond has partial double-bond character / is planar, restricting rotation around the bond and contributing to the regularity of secondary structures such as the alpha-helix or beta-pleated sheet.

## Key terms

- [peptide bond](https://www.gradenine.co.uk/glossary/peptide-bond)

## 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-peptide-bond-is-f25a318b) · Published by Druglandscape Ltd.