The Definition of a Lipid
Lipids are compounds that occur frequently in nature. They are found in places component of plant, animal, and microbial membranes. The definition of a as diverse as egg yolks and the human nervous system and are an important readily soluble in organic solvents, such as chloroform or acetone. lipid is based on solubility. Lipids are marginally soluble (at best) in water but readily soluble in organic solvents, such as chloroform or acetone.
Fats and oils are typical lipids in terms of their solubility, but that fact does not really define their chemical nature. In terms of chemistry, lipids are a mixed bag of compounds that share some properties based on structural simi- larities, mainly a preponderance of nonpolar groups.
Classified according to their chemical nature, lipids fall into two main groups. One group, which consists of open-chain compounds with polar head groups and long nonpolar tails, includes fatty acids, triacylglycerols, sphingolipids, phosphoacylglycerols, and glycolipids. The second major group consists of fused- ring compounds, the steroids; an important representative of this group is cholesterol.
Lipids are compounds that consist mostly of nonpolar groups. They have limited solubility in water, but dissolve freely in organic solvents.