molecule

/ˌmɑləˈkjul/

/ˈmɒləkjul/

Other forms: molecules

A molecule is the simplest structural unit of a substance that still keeps the properties of that substance, like a molecule of water. This scientific word also gets used in unscientific ways, as in "Every single molecule in my body wants that chocolate cupcake!"

People sometimes confuse molecules with atoms, but a molecule is made up of atoms. A molecule retains the characteristic of the substance it’s from, so a water molecule is still water. An atom only has the characteristics of its element, not the larger composition. For example, a water molecule, H2O, is made up of two hydrogen atoms and one oxygen atom.

Definitions of molecule

1. noun

   (physics and chemistry) the simplest structural unit of an element or compound
   types:

   dipole molecule

   a molecule that is a permanent dipole

   protein molecule

   any large molecule containing chains of amino acids linked by peptide bonds

   coenzyme

   a small molecule (not a protein but sometimes a vitamin) essential for the activity of some enzymes

   EDTA, ethylenediaminetetraacetic acid

   a complex molecule used medically to chelate metal ions in cases of lead or heavy metal poisoning

   macromolecule, supermolecule

   any very large complex molecule; found only in plants and animals

   protein

   any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes

   carbohydrate, saccharide, sugar

   an essential structural component of living cells and source of energy for animals; includes simple sugars with small molecules as well as macromolecular substances; are classified according to the number of monosaccharide groups they contain

   cocarboxylase, thiamine pyrophosphate

   a coenzyme important in respiration in the Krebs cycle

   coenzyme A

   a coenzyme present in all living cells; essential to metabolism of carbohydrates and fats and some amino acids

   lipid, lipide, lipoid

   an oily organic compound insoluble in water but soluble in organic solvents; essential structural component of living cells (along with proteins and carbohydrates)

   NAD, nicotinamide adenine dinucleotide

   a coenzyme present in most living cells and derived from the B vitamin nicotinic acid; serves as a reductant in various metabolic processes

   NADP, nicotinamide adenine dinucleotide phosphate

   a coenzyme similar to NAD and present in most living cells but serves as a reductant in different metabolic processes

   nucleic acid

   (biochemistry) any of various macromolecules composed of nucleotide chains that are vital constituents of all living cells

   triphosphopyridine nucleotide

   a coenzyme of several enzymes

   coenzyme Q, ubiquinone

   any of several quinones found in living cells and that function as coenzymes that transfer electrons from one molecule to another in cell respiration

   type of:

   building block, unit

   a single undivided natural thing occurring in the composition of something else
2. noun

   (nontechnical usage) a tiny piece of anything
   synonyms: atom, corpuscle, mote, particle, speck

   types:

   grain

   a relatively small granular particle of a substance

   grinding

   material resulting from the process of grinding

   chylomicron

   a microscopic particle of triglycerides produced in the intestines during digestion; in the bloodstream they release their fatty acids into the blood

   flyspeck

   a tiny dark speck made by the excrement of a fly

   identification particle

   a tiny particle of material that can be added to a product to indicate the source of manufacture

   granule

   a tiny grain

   Microtaggant

   (trademark) a microscopic and traceable identification particle used to trace explosives or other hazardous materials or to prevent counterfeiting

   type of:

   material, stuff

   the tangible substance that goes into the makeup of a physical object