[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Cholesterol

[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Cholesterol

Cholesterol is a 27-carbon sterol that stiffens membranes and is the raw material for steroid hormones, bile acids and vitamin D.

Updated 2026-11-01

Loading the 3D model…

## Key facts

- Four fused rings, an OH on C3 and an 8-carbon side chain: amphipathic but almost insoluble in water.
- It travels in blood inside lipoproteins, about two-thirds as cholesteryl ester.
- The body makes it (mainly the liver) and gets it from animal foods; plants contain no cholesterol.
- It is not broken down to CO₂: it leaves the body as cholesterol in bile and as bile acids.
- Desirable total cholesterol in adults: below 200 mg/dL.

**Formula**
C₂₇H₄₆O

**PubChem**
[CID 5997](https://pubchem.ncbi.nlm.nih.gov/compound/5997)

## Structure

- The C3 OH faces the water and the rest sinks between phospholipids: it stiffens fluid membranes and loosens rigid ones.
- Cholesteryl ester loses the free OH and is even more hydrophobic: it is stored in lipid droplets or the lipoprotein core.

## Clinical notes

- High LDL deposits cholesterol in the artery wall and forms atheromatous plaques.
- Bile supersaturated with cholesterol forms gallstones.
- Tendon xanthomas or corneal arcus in a young person suggest familial hypercholesterolaemia.

## Pathways

- [Cholesterol synthesis (mevalonate pathway)](https://durgical.com/en/biochemistry/pathways/cholesterol-synthesis/)
- [Adrenal cortisol synthesis](https://durgical.com/en/biochemistry/pathways/adrenal-cortisol-synthesis/)
- [Classic bile acid synthesis pathway](https://durgical.com/en/biochemistry/pathways/classic-bile-acid-synthesis-pathway/)

## Related conditions

- [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/)
- [Gallstones (cholelithiasis)](https://durgical.com/en/conditions/gallstones/)
- [Familial hypercholesterolemia](https://durgical.com/en/conditions/familial-hypercholesterolemia/)

## Related

- [Lanosterol](https://durgical.com/en/biochemistry/molecules/lanosterol/)
- [HMG-CoA reductase](https://durgical.com/en/biochemistry/enzymes/hmg-coa-reductase/)
- [LDL (low-density lipoprotein)](https://durgical.com/en/biochemistry/topics/ldl/)
- [HDL (high-density lipoprotein)](https://durgical.com/en/biochemistry/topics/hdl/)
- [Bile acid synthesis](https://durgical.com/en/biochemistry/topics/bile-acid-synthesis/)
- [Steroid hormone synthesis (overview)](https://durgical.com/en/biochemistry/topics/steroid-hormone-synthesis/)
- [Cholic acid](https://durgical.com/en/biochemistry/molecules/cholic-acid/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which three groups of molecules are made from cholesterol?

Steroid hormones, bile acids and vitamin D (from 7-dehydrocholesterol).

## How does the body get rid of cholesterol if it does not oxidise it to CO₂?

It excretes it in bile, both as free cholesterol and converted to bile acids.

## Why does cholesteryl ester sit in the lipoprotein core?

Without the free OH it is fully hydrophobic and cannot stay on the water-facing surface.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/molecules/cholesterol/)

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Cholesterol (CID 5997)](https://pubchem.ncbi.nlm.nih.gov/compound/5997) (PubChem, NCBI, 2026) · Public domain; [Cholesterol | High Cholesterol | MedlinePlus](https://medlineplus.gov/cholesterol.html) (MedlinePlus, US National Library of Medicine, 2026); [High blood cholesterol levels: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000403.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

[← All of biochemistry](https://durgical.com/en/biochemistry/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/biochemistry/molecules/cholesterol/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/cholesterol/