Essential Bioelements and Biomolecules in Living Organisms

Essential Bioelements in Living Organisms

Bioelements are chemical elements that constitute biomolecules. The majority have incomplete external electronic layers and a lower atomic number, allowing them to be easily incorporated into living organisms.

Classification of Bioelements

• Primary Bioelements: These majority elements constitute 99% of living matter and include C, H, O, N, P, and S.
• Secondary Bioelements: Found in all living things, but to a lesser extent, these include Na, K, Ca, Mg, and Cl.
• Trace Elements: Present in proportions below 0.1%, these are equally essential. Some, such as Fe, Cu, Zn, Mn, I, Ni, and Co, are present in most organisms. Others, like Si, F, Cr, Li, B, Mo, and Al, are found only in specific groups.

Biomolecules: The Building Blocks of Life

Also called immediate principles, biomolecules are the molecular components of living things. They can be classified as:

• Inorganic: Water and minerals
• Organic: Carbohydrates, lipids, proteins, and nucleic acids

Water: The Foundation of Life

Water is the most abundant molecule in living things. Its presence depends on the species, the individual's age, and the type of tissue or organ. The union between oxygen and hydrogen is made by covalent bonds, where each hydrogen atom shares a pair of electrons with the oxygen atom. The water molecule has partial electric charges, a triangular geometry (hydrogen atoms form a 104.5° angle with oxygen), and a dipolar character.

The angled chemical structure and polarity allow for hydrogen bonds between water molecules and other polar molecules (alcohols, amines, etc.). Water's polarity gives it great solvent power. Hydrogen bonds are responsible for these properties:

• Liquid state at room temperature
• Compressibility
• Capillarity
• High surface tension
• High specific heat of vaporization
• Lower density of ice compared to liquid water

Some water molecules undergo ionization, where a hydrogen atom attached by a covalent bond to an oxygen atom is also attached by a hydrogen bond to another molecule. This results in two ions: H₃O⁺ and OH^-.

Biological Functions of Water

• Medium for biochemical reactions
• Temperature regulation
• Molecular transport
• Lubrication of moving structures
• Cellular and cytoplasmic movement
• Hydrostatic skeleton in plant cells
• Hydrolysis

Mineral Salts: Essential for Biological Functions

Mineral salts are inorganic compounds that can be soluble or insoluble in water. Soluble salts are ionized, while insoluble salts precipitate. They play vital roles in:

• Regulation of metabolic and physiological processes
• Maintaining appropriate osmotic concentrations for cellular stability and vital functions
• Maintaining pH in biological structures and preventing alteration and loss of function of biomolecules

To avoid pH variations in biological fluids (intracellular and extracellular), buffer systems are involved. These are composed of a weak acid and its conjugate base, such as phosphate buffer and bicarbonate buffer.