Cholesterol biosynthesis

Cholesterol is a waxy steroid metabolite found in the cell membranes and transported in the blood plasma of all animals. It is an essential structural component of mammalian cell membranes, where it is required to establish proper membrane permeability and fluidity. In addition, cholesterol is an important component for the manufacture of bile acids, steroid hormones, and several fat-soluble vitamins. Cholesterol is the principal sterol synthesized by animals, but small quantities are synthesized in other eukaryotes, such as plants and fungi. It is almost completely absent among prokaryotes, which include bacteria. Source: [[wikipedia:Cholesterol|Wikipedia]]

胆固醇是一种存在于所有动物细胞膜和血液血浆中的蜡质类固醇代谢产物。它是哺乳动物细胞膜不可或缺的结构组成部分，对于维持细胞膜的适宜渗透性和流动性至关重要。此外，胆固醇是胆汁酸、类固醇激素以及多种脂溶性维生素合成的重要成分。动物是胆固醇的主要合成者，但在其他真核生物如植物和真菌中也存在少量合成。在包括细菌在内的原核生物中，胆固醇几乎完全不存在。信息来源：[维基百科：胆固醇](https://zh.wikipedia.org/wiki/Cholesterol)（英文：[wikipedia:Cholesterol](https://en.wikipedia.org/wiki/Cholesterol)）