Lipid Structure and Functions

Lipids come in two main forms depending on temperature - solid fats and liquid oils at room temperature. They're incredibly versatile molecules that include fatty acids, triglycerides, and cholesterol.

Your body relies on lipids for multiple essential functions. They serve as a major energy source through respiration to produce ATP, and they're stored in adipose cells for long-term energy reserves. Beyond energy, lipids form the structure of cell membranes and provide both thermal and electrical insulation.

Saturated lipids have no double bonds between carbon atoms and tend to be solid fats. In contrast, unsaturated lipids contain one or more double bonds (mono-unsaturated has one, poly-unsaturated has multiple). These double bonds create kinks in the molecular chain, making the lipid more fluid.

Triglycerides form through condensation reactions between glycerol and fatty acids, creating ester bonds. When your body needs to break these down, enzymes like lipase catalyse hydrolysis reactions, particularly in the small intestine.

Key Insight: The presence or absence of double bonds in lipids determines whether they're solid or liquid at room temperature - this is why butter (saturated) is solid while olive oil (unsaturated) flows freely.