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Which major types of organic molecules make up a typical mammalian cell?

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Diagram showing how epinephrine binding to a beta-adrenergic receptor on a cell membrane activates a G-protein, which then stimulates adenylyl cyclase to convert ATP into cyclic AMP (cAMP), leading to physiological effects such as increased heart rate, blood vessel dilation, and glycogen breakdown. — Biochemistry In biochemistry, researchers study the chemical substances and processes that occur in living organisms and cells. In particular, various processes by which cells gain energy, such as epinephrine-stimulated cAMP synthesis, have been deduced through the study of biochemistry.

A typical mammalian cell is composed primarily of water, which accounts for approximately 70% of its total weight. Beyond water, the cell is largely built from four families of small organic molecules: sugars, amino acids, nucleotides, and fatty acids.1

These small molecules serve as the building blocks for larger macromolecules, which constitute the majority of the cell's remaining mass. The major types of these organic molecules include:1

Proteins: The largest portion of cellular macromolecules (about 18% of total cell weight), formed by linking amino acids.1
Lipids: Including phospholipids and other fats (about 5% of cell weight), which are essential for forming cell membranes.1
Polysaccharides: Complex carbohydrates (about 2% of cell weight) formed from sugars.1
Nucleic Acids: Including DNA (0.25%) and RNA (1.1%), which are constructed from nucleotides.1

Additionally, cells contain miscellaneous small metabolites (3%) and inorganic ions (1%). These molecules are vital for structural integrity, energy storage, and the catalytic functions performed by enzymes.12