---
title: "Urea cycle Template – Free Chemistry Diagram | MolDraw"
url: https://www.moldraw.com/templates/biopath-urea-cycle/
description: "Urea cycle template: Carbamoyl phosphate (CPS I), then ornithine → citrulline (OTC) → argininosuccinate (ASS) → arginine + fumarate (ASL) → ornithine + urea…"
lang: en
publisher: Scidart Academy
generated: 2026-10-28
---
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# Urea cycle template

![Urea cycle template: Carbamoyl phosphate (CPS I), then ornithine → citrulline (OTC) → argininosuccinate (ASS) → arginine + fumarate (ASL) → ornithine + urea (arginase), with ATP use and the matrix/cytosol split.](https://www.moldraw.com/templates/download/biopath-urea-cycle.svg)

[Edit in MolDraw](https://www.moldraw.com/)[Download SVG](https://www.moldraw.com/templates/download/biopath-urea-cycle.svg)

Free template. Download it, or open it in MolDraw to change it first.

Carbamoyl phosphate (CPS I), then ornithine → citrulline (OTC) → argininosuccinate (ASS) → arginine + fumarate (ASL) → ornithine + urea (arginase), with ATP use and the matrix/cytosol split.

## What the template shows

- Liver cells turn waste NH₄⁺ into urea: two steps in the mitochondrial matrix, three in the cytosol
- Mitochondrial matrix: carbamoyl phosphate
- CPS I needs N-acetylglutamate as an allosteric activator
- carbamoyl phosphate
- The cycle
- OTC works in the matrix; citrulline leaves for the cytosol, where ASS, ASL and arginase work, and ornithine returns
- one per turn, excreted by the kidney
- Fumarate returns aspartate (the “Krebs bicycle”)
- Cytosolic fumarase and malate dehydrogenase, then transamination
- Overall: NH₄⁺ + HCO₃⁻ + aspartate + 3 ATP + H₂O → urea + fumarate + 2 ADP + AMP + 2 Pᵢ + PPᵢ, i.e. four high-energy phosphate bonds per urea.
- Urea’s two N come from NH₄⁺ (via carbamoyl phosphate) and from aspartate; its C comes from HCO₃⁻.
- CPS I = carbamoyl phosphate synthetase I, OTC = ornithine transcarbamoylase, ASS = argininosuccinate synthetase, ASL = argininosuccinate lyase.
- Defects in any enzyme raise blood NH₄⁺ (hyperammonaemia). AST = aspartate aminotransferase; acids and amines are drawn neutral.

Drawn with 105 atoms, 8 arrows, 3 shapes – every one editable in MolDraw.

## Sources

- [Nelson & Cox, Lehninger Principles of Biochemistry, 8th ed., 2021, ch. 18](https://openlibrary.org/isbn/9781319228002) Textbook
- [Berg, Tymoczko, Gatto & Stryer, Biochemistry, 9th ed., 2019](https://openlibrary.org/isbn/9781319114657) Textbook
- [Voet & Voet, Biochemistry, 4th ed., Wiley 2011](https://openlibrary.org/isbn/9780470570951) Textbook

## How to use this template

1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor.
2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need.
3. Add your own structures, arrows and text next to it, or combine several templates on one page.
4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers.

## Frequently asked questions

### Is the Urea cycle template free?

Yes. The Urea cycle template is one of the free MolDraw templates: open it in the editor or download it from this page as SVG or PNG and use it in your slides, worksheets and notes.

### Can I edit the Urea cycle template?

Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.

### Is the chemistry checked?

Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.

### Are the biochemical pathways drawn with structures?

Yes. Pathway templates show the intermediates as structures, with enzymes and cofactors (NAD⁺, FAD, ATP) on the arrows.

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