
The Cellular System and the Code of Life 5
(Na
+
, K
+
, Ca
2+
, Cl
-
, Mg
2+
, etc.), monosaccharides, fatty acids, amino acids, and
nucleotides. Major varieties of large molecules are polysaccharides, lipids,
proteins, and nucleic acids (DNA and RNA). Among these components,
the inorganic ions are important for signaling (e.g., waves of Ca
2+
represent
important intracellular signal), cell energy storage (e.g., in the form of Na
+
/ K
+
cross- membrane gradient), or protein structure/ function (e.g., Mg
2+
is
an essential cofactor for many metalloproteins). Carbohydrates (including
monosaccharides and polysaccharides), fatty acids, and lipids are ...