Inorganic Molecules and Their Essential Roles in Living Organisms

General Characteristics of Inorganic Molecules

• Living compounds are bifurcated into two primary categories: inorganic molecules and organic molecules.

• The principal inorganic molecules include Water ($H_2O$), Salts, and Minerals.

• Production and Intake: These molecules are not produced by living organisms; instead, they are obtained externally from the environment.

• Physical Properties: They are small enough to pass through cell membranes without requiring prior digestion.

• Energy Production: Generally, inorganic molecules do not provide energy. However, an exception exists for kemosentetik (chemosynthetic) organisms, which meet their energy requirements by oxidizing inorganic substances.

• Biological Roles: They function as constructive, repairing, and typically regulatory molecules.

• Toxicity Caveat: While most minerals are regulatory, certain substances like Lead ($Pb$) and Mercury ($Hg$) are minerals that exert toxic effects and are not considered regulatory.

Biological Importance and Properties of Water ($H_2O$)

• Vital Significance: Water is the most abundant substance found in nature and within the structure of organisms, making it essential for life.

• Atomic Structure: A water molecule is composed of two positively charged hydrogen ($H$) atoms and one negatively charged oxygen ($O$) atom.

• Water Ratios in the Human Body:

  • Age-Based Distribution:
    • Baby: $75-78\%$
    • Adult Male: $60\%$
    • Adult Female: $50-55\%$
    • Elderly: $45-50\%$
    • Average Adult Overall: $60\%$
  • Tissue and Organ Distribution:
    • Brain: $78-80\%$
    • Blood: $90\%$
    • Muscles: $75-78\%$
    • Others (e.g., Liver, Skin): $70-75\%$
    • Bones: $30-31\%$

• Primary Functions of Water:

  • Temperature Balance: Facilitates the regulation of body temperature.
  • Waste Removal: Involved in the excretion of metabolic wastes.
  • Cell Structure: Provides structural integrity to cells.
  • Transport: Acts as a medium for moving substances within the organism.

• Physical and Chemical Properties of Water:

  • Adhesion: This is the attractive force between water and a different surface, allowing water to stick to its surroundings. An example is water adhering to a glass surface or roots.
  • Cohesion: This is the attractive force between identical molecules (water molecules sticking to each other).
  • Surface Tension: Cohesion generates surface tension, which allows very light insects to move across the surface of the water without sinking.
  • Biological Transport: In plants, the combined forces of adhesion and cohesion are responsible for transporting water from the roots all the way to the leaves.
  • Solubility: Water is a superior solvent. This property enables plants to absorb minerals and necessary nutrients from the soil. It allows sugar to dissolve rapidly and facilitates metabolic activities within living things.
  • High Heat Capacity: Water stores heat energy and does not release it quickly.
    • Global Impact: During summer, oceans absorb solar energy while their temperature only fluctuates by $1$ to $2$ degrees. Without this capacity, summer temperatures would become uninhabitable and winter temperatures would cause immediate freezing.
    • Regional Impact: Cities by the sea (such as Antalya and İzmir) experience very little temperature difference between night and day due to the balancing effect of large water masses. Conversely, inland cities far from the sea (such as Ankara and Konya) experience extreme heat during the day and freezing temperatures at night because they lack this balancing effect.
  • Density and Freezing: Unlike most substances, water expands when it freezes, increasing its volume while its mass remains constant, which makes ice lighter than liquid water.
    • Aquatic Survival: When a lake freezes, the ice remains at the top. This ice layer acts as a thermal insulator, preventing cold outside air from entering the water below, thus maintaining a habitable environment for aquatic life.
  • Enzymatic Function: A minimum water concentration of $15\%$ is required in the environment for enzymes to function. Enzymes accelerate chemical reactions; if the environment lacks sufficient water, enzymes cannot work, and metabolic activities may cease.

Characteristics and Functions of Minerals

• Definition: Minerals are inorganic molecules that living beings require but cannot produce themselves.

• Acquisition: Plants absorb minerals from the soil, while animals obtain them through food consumption. They are naturally found in soil, water, and rocks in various forms.

• General Properties:

  • They do not provide energy.
  • They are regulatory in nature.
  • Their deficiency leads to specific diseases.

• Specific Minerals and Their Roles:

  • Iron ($Fe$): Enters the structure of hemoglobin (the substance that gives blood its red color). Deficiency leads to Anemia (low blood count). Found in spinach and red meat.
  • Phosphorus ($P$): Participates in the structure of bones, teeth, DNA, and ATP. Deficiency causes bone weakness and growth retardation. Found in meat, milk, and legumes.
  • Iodine ($I$): Enters the structure of the thyroxine hormone produced by the thyroid gland. Deficiency causes Goiter ($Guatr$) and intellectual disability. Found in seafood.
  • Potassium ($K$): Regulates heart rhythm and nerve conduction. Deficiency causes heart rhythm disorders ($aritmi$). Found in bananas, potatoes, and apricots.
  • Sodium ($Na$): Regulates body fluid balance and nerve conduction. Deficiency results in loss of appetite and muscle cramps. Found in table salt and mineral water.
  • Calcium ($Ca$): Participates in bone and tooth structure and is effective in blood clotting. Deficiency leads to Osteoporosis (bone loss). Found in milk, cheese, and yogurt.
  • Magnesium ($Mg$): Regulates enzyme activity, the muscular system, and the nervous system. Deficiency causes neural disorders and muscle cramps. Found in hazelnuts, almonds, and green vegetables.
  • Sulfur ($S$): Participates in the structure of certain amino acids. Deficiency causes paleness in the skin and hair. Found in meat, onions, and garlic.
  • Zinc ($Zn$): Effective on the immune system. Deficiency results in immune weakness. Found in seafood and hazelnuts.
  • Fluorine ($F$): Provides the protection of tooth and bone health. Deficiency leads to tooth decay. Found in seafood.
  • Chlorine ($Cl$): Contributes to the formation of stomach acid ($HCl$). Deficiency causes digestive problems. Found in table salt.

Comparative Summary of Inorganic Molecules

• Digestibility: Inorganic molecules (Water and Minerals) are not digestible.
• Energy Provision: They are not used as energy sources by living organisms.
• Production: They are not produced by living organisms.
• Membrane Permeability: They can pass through the cell membrane.
• Structural Role: They participate in the construction/structure of living organisms.
• Regulatory Role: They perform tasks in the regulation of vital activities.

Terminology and Puzzle Solutions

• Cohesion ($Kohezyon$): The attractive force between molecules of the same type.
• Sulfur ($Kükürt$): A mineral whose deficiency causes wilting in the young leaves of plants.
• Goiter ($Guatr$): A disease occurring due to Iodine deficiency.
• Adhesion ($Adezyon$): The attractive force between molecules of different types.
• Magnesium ($Magnezyum$): A mineral found abundantly in green-leaved plants and nuts.
• Zinc ($Çinko$): A mineral whose deficiency leads to the weakening of the immune system.
• Sodium ($Sodyum$): A mineral that provides fluid-electrolyte balance in the body.
• Iron ($Demir$): A mineral responsible for oxygen transport in the blood.
• Calcium ($Kalsiyum$): A mineral important for bone and tooth health.
• Potassium ($Potasyum$): A mineral whose deficiency causes irregularities in heartbeats.