How do lipids differ from proteins?

While proteins consist of C, H, O, and S (in rare cases), lipids are defined as triglycerides, which are composed of three fatty acid molecules and one glycerol molecule. Protein molecules are composed of amino acids, of which there are over 20 different kinds. Triglycerides that contain saturated fatty acids are known as fats and are solid at room temperature, while those that contain unsaturated fatty acids are known as oils and are liquid. Proteins are not affected by this distinction.

Lipids are hydrophobic molecules composed primarily of carbon and hydrogen atoms, while proteins are composed of amino acids linked together by peptide bonds. Lipids are insoluble in water, whereas proteins are soluble in water. Lipids serve as energy storage molecules and form cell membranes, while proteins have diverse functions including enzyme catalysis, structural support, and signaling.