Life did not emerge from nothing—it is a miracle meticulously curated from the inorganic world. When we dissect a cell, we find its interior resembles a sophisticatedelement-reshaping factory. Although all chemical elements found in cells can also be found in the inorganic world—reflecting theunity between the living and non-living worlds—life reshapes concentrations to put carbon, hydrogen, oxygen, and nitrogen center stage, demonstrating remarkablediversity.

Classification and Functions of Elements

• Macroelements: These include $C, H, O, N, P, S, K, Ca, Mg$. They form the "structural backbone" of life.
• Microelements: Such as $Fe, Mn, Zn, Cu, B, Mo$. Few but vital—for example, $Zn$ participates in the activity of hundreds of enzymes; zinc deficiency can impair development.
• The Core of Life: Carbon ($C$) is the central element of life—all biological macromolecules are built on a carbon backbone.

Forms of Matter

Most elements in cells exist in the form of compounds. In fresh weight, water is the champion; in dry weight,proteins (7%–10%) take the lead. The wonder of life is that—from the most primitivenucleoidstructure to complexunsaturated fatty acidsregulation, and even futuresynthetic life—all follow the same chemical logic.