Bioelements, Biomolecules and Water

Bioelements and Biomolecules

• For the formation of organic biomolecules, inorganic substances are necessary.
• Primary bioelements include Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur, making up approximately 96% of organic matter.
• Secondary bioelements like Calcium, Sodium, Potassium, Chlorine, and Magnesium constitute 2-4% and play a fundamental role in living beings' functioning.
• Oligoelements such as Iron, Zinc, Iodine, Lithium, Silicon, Fluorine, Cobalt, and Manganese make up less than 0.1% but are indispensable for physiological processes.
• Bioelements are elements present in living matter and are non-metallic.
• They have a small atomic mass and a greater tendency to form covalent bonds.
• Organic molecules contain functional groups such as hydroxyl (-OH), carbonyl (ketone, -C=O), carbonyl (aldehyde, -C=O H), amino (-NH2), and carboxyl (-CO).

Water (H₂O)

• Water can be found in three forms in the organism: circulating, interstitial (between cells), and intracellular (cytosol).
• The water molecule behaves as a dipole, possessing two poles with different charges.
• Water would be a gas at room temperature if not for its molecular mass; water's hydrogen bonds form a network that explains its liquid state at ambient temperatures.
• Carbon is based on carbon chemistry and can make 4 bonds.
• Being covalent, it forms stable structures distributed in a three-dimensional form, leading to diverse types of structures (linear, cyclic, branched).

Physical-Chemical Properties of Water

• High cohesion force between its molecules due to hydrogen bonds keeps water molecules together.
• High surface tension results from the resistance of molecules to separation.
• High specific heat means much energy is needed to raise the temperature of a mass of water by 1°C.
• High vaporization heat, meaning much energy is required to convert liquid water into vapor, making sweat an efficient coolant.
• Water has lower density in solid form (ice) than in liquid form; ice floats in water, and water has a maximum density at 4°C.
• Water has great solvent capacity due to its polarity for iconic compounds
• Strong adhesive force causes water molecules' tendency to stick to the walls of vessels, contributing to phenomena like sap ascent in plants.

Functions of Water

• Transportation, such as in blood.
• Dissolution, as biochemical reactions occur in an aqueous medium.
• Structural component of cells.
• Capillary action.
• Thermoregulation.
• Ecological role, such as life under ice.
• Acts as a shock absorber, like synovial fluid.

Mineral Salts

• Precipitated salts form structural components like bones and shells (e.g., CaCO3).
• Dissolved salts (ions) perform various functions.
• Nerve impulse transmission depends on Na+ and K+.
• Muscle contraction depends on Ca2+.
• Metabolic reactions and salinity
• Buffer for biological processes.
• Mg2+ and Na+ facilitate the transport of O2 and CO2, and Mg2+ is part of chlorophyll.
• Neurotransmitter release depends on Ca2+ at the axon’s end.
• pH = -log[H+] measures the alkalinity or acidity of a solution, depending on [H+].
• Biological mediums have their buffer solutions, and intracellular fluid should maintain its pH stable(homeostasis) .
• Blood has a pH between 7.35-7.45, while intracellular fluid's pH ranges from 6.4-7.4.
• Buffer solutions containing dissolved mineral salts can cushion small pH changes internally.
• The phosphate buffer in the cell's interior maintains a stable intracellular pH.

Bicarbonate Buffer

• Bicarbonate buffer (in blood) involves CO2 + H2O being interconverted to H2CO3, which then forms HCO3- + H+.
• During hyperventilation, a decrease in [CO2] in the blood causes alkalosis. Th buffer attempts to compensate by producing CO2.
• Hypoventilation leads to a rise of O2.

Diffusion and Osmosis

• Diffusion and osmosis are very important for cells.
• Diffusion distributes particles homogeneously from a high concentration to a lower concentration.
• Gases pass through diffusion within cells.
• Osmosis occurs across semipermeable membranes allowing the passage of solvents to equalize concentration.
• Solute cannot pass; the solvent moves in osmosis to balance concentrations.
• A red blood cell in an isotonic medium is in equilibrium.
• In a Hypertonic Environment water exits the cell, leading to plasmolysis.
• In a Hypotonic Environment water enters the cell, potentially causing lysis and finally the globule will burst

Turgidity

• Turgidity needs to kept at the right levels, not to much
• For Flowers can occur the the cells are bloated, and hold for a bit longer
• Eventually the flowers decay, and die due to lack of nutrients

Food Preservation Techniques

• Adding salt can kill microoganisms. This is achived by dehydrating the microganisms
• Excess sugar can kill microorganism, due to the hypertonic enviroment and dehrdatation