Question

How is the definition of "lipid" different from the types of definitions used for other biomolecules, such as amino acids, nucleic acids, and proteins?

Answer 1

Lipids are defined by their solubility properties rather than specific functional groups, encompassing a range of nonpolar hydrophobic molecules, unlike proteins and nucleic acids, which have more specific structural criteria.

Step-by-step explanation:

The definition of "lipid" differs from other biomolecules like amino acids, nucleic acids, and proteins because lipids are defined not by the presence of specific functional groups but by their physical property of solubility. A lipid is a broad category, which includes a diverse range of hydrophobic or nonpolar molecules that are more soluble in nonpolar solvents like ether or chloroform than in water. This encompasses various molecules such as triglycerides, phospholipids, and steroids. The criterion for a molecule to be classified as a lipid is based on its solubility characteristics rather than a specific structural formula. For example, triglycerides are formed by a glycerol molecule bonded to three fatty acid molecules and are the main component of body fat in humans and other animals.

Proteins, on the other hand, are defined by the presence of one or more long chains of amino acids. Amino acids and nucleic acids have well-defined structures involving specific atoms in certain arrangements, making the classification of these molecules less ambiguous compared to lipids. Lipids play various roles such as energy storage, structural components of cell membranes, and as signaling molecules.

Answer 2

The term "lipid" does not specify a particular chemical structure. Whereas one can write a general formula for an amino acid, nucleic acid, or protein, lipids are much more chemically diverse. Compounds are categorized as lipids based on their greater solubility in organic solvents than in water.