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1.3.2. Mineral salts

Mineral salts

The minerals can be found in living things in three ways:

Precipitated mineral salts

Precipitated mineral salts constitute solid, insoluble structures with skeletal function. For instance:

  • Calcium carbonate in the shells of molluskscrustaceans, corals and vertebrates.
  • Calcium phosphate, Ca3 (PO4)2, which, together with calcium carbonate, which, deposited on collagen, constitute bones.
  • Silica (SiO2) in the exoskeletons of diatoms and grasses, etc.

Dissolved mineral salts

The dissolved mineral salts are dissociated into ions:

  • Cations: Na+, K+, Ca2+ and Mg2+.
  • Anions: Cl-, SO42-, PO42-, HCO3-, CO32- and NO3-.

Mineral salts associated with organic molecules

The minerals associated to organic molecules typically found with proteins, such as phosphoproteins; together with lipids, such as phospholipids, and with carbohydrates, as in agar-agar.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.