Final answer:
Lipids are hydrophobic organic compounds, made mostly of hydrocarbons, that are insoluble in water due to their nonpolar nature. They differ from other water-soluble, polar organic molecules in their solubility properties. Examples in human biology include fats, phospholipids, waxes, and steroids.
Step-by-step explanation:
Definition of Lipids
Lipids are a diverse group of hydrophobic, or water-insoluble, organic compounds made up mostly of hydrocarbons. The nonpolar nature of lipids comes from the carbon-carbon or carbon-hydrogen bonds which do not mix well with water, a polar solvent. Unlike polar molecules, which are hydrophilic and soluble in water, lipids are hydrophobic and tend to form emulsions rather than true solutions when mixed with water.
Differences Between Lipids and Other Organic Molecules
One of the key differences between lipids and other organic molecules is their solubility in water. Lipids are nonpolar and hydrophobic, thus they do not dissolve in water. In contrast, many other organic molecules, which are polar or have ionic groups, are soluble in water because of the attraction between the polar water molecules and the charged parts of the molecules.
Examples of Lipids in Human Biology
Examples of lipids in human biology include fats, which are stored energy within cells, phospholipids, which are a major component of cell membranes, waxes, which provide protection and insulation, and steroids, which are building blocks for hormones like cholesterol.