Derived lipids are formed from simple lipids via enzymatic activities or chemical modifications. For example, when simple lipids such as triglycerides undergo hydrolysis, they are broken down into glycerol and 3 fatty acids. This reaction is catalyzed by lipases. This reaction yields glycerol and free fatty acids, which can be modified again and used by cells for energy generation in the TCA cycle, or for the synthesis of other molecules. Other examples of derived lipids include steroids, terpenes, ketones, and alcohols.