The biosynthetic transformation of acetyl CoA into the isoprene derived squalene opens cholesterol synthesis. Cholesterol modulates the fluidity of eukaryotic membranes and steroid hormones are derived from cholesterol. Also, bile salts are polar derivatives of cholesterol released by the gall bladder to solubilize dietary lipids.The biosynthesis of cholesterol from squalene (six isoprene units) begins with epoxide formation to form squalene 2,3-epoxide. Multiple ring formation in squalene 2,3 epoxide is triggered by epoxide ring opening.