Makindo Medical Notes

🌍 Life depends on chemistry: every heartbeat, thought, and breath reflects countless atoms of oxygen, carbon, hydrogen, and other elements forming and breaking bonds. ⚡ These dynamic interactions create the structure of biomolecules and drive metabolism, energy transfer, and signalling.

🔗 Types of Chemical Bonds

• ⚡ Ionic Bonds: Ions are charged atoms formed when one atom donates or accepts electrons.
  • Positive = cation (e.g., Na⁺)
  • Negative = anion (e.g., Cl⁻)
  • Opposite charges attract → form ionic bonds (e.g., NaCl crystals).
  • Biological relevance: Key in nerve conduction, muscle contraction, and electrolyte balance.
• 🔗 Covalent Bonds: Electrons are shared between atoms.
  • Nonpolar covalent bonds: Equal sharing of electrons → electrically neutral molecules (e.g., O₂, CH₄). 🧪 Basis of lipid membranes (hydrophobic tails).
  • Polar covalent bonds: Unequal sharing → “poles” of charge (e.g., H₂O). 💧 This underlies solubility and hydrogen bonding.
  • Biological relevance: Stable backbone of DNA, proteins, carbohydrates.
• 💧 Hydrogen Bonds: A weak but vital interaction when a hydrogen atom covalently bound to an electronegative atom (O, N) is attracted to another electronegative atom.
  • Weaker than covalent/ionic bonds but crucial for life.
  • Stabilises DNA double helix, protein secondary structures (α-helix, β-sheet).
  • Gives water its unique properties: high boiling point, surface tension, excellent solvent.

🧬 Integration in Biology

In living organisms, bonds constantly form and break to allow flexibility and energy flow:

• 💧 Water: Polar covalent bonds → hydrogen bonding → solvent of life.
• 🧂 Ionic interactions: Salt (NaCl) dissolves via ion-dipole interactions with water.
• 🥑 Nonpolar covalent bonds: Hydrophobic lipids cluster in membranes → essential for cell structure.
• 🧩 Proteins: Hydrogen bonds + ionic interactions stabilise folding and enzyme function.

📊 Clinical & Physiological Relevance

• ⚡ Electrolyte imbalance: Low Na⁺, K⁺, or Ca²⁺ disrupt ionic gradients → arrhythmias, seizures.
• 🧬 DNA damage: Breaking hydrogen bonds → mutation or apoptosis.
• 🌡️ Fever: Alters hydrogen bonding in proteins → denaturation at high temperatures.

🧂 Dissociation of Sodium Chloride in Water

NaCl does not dissolve as intact molecules but dissociates into Na⁺ cations and Cl⁻ anions, each surrounded by water molecules (hydration shells) → stabilising ions in solution. 🔑 This principle explains conduction in nerves and osmotic gradients.

✅ Conclusion

From ionic Na⁺/Cl⁻ gradients powering nerve impulses, to hydrogen bonds shaping DNA and proteins, chemical bonds are the language of biology. 🔑 Understanding these interactions helps explain everything from cell signalling and drug action to genetic inheritance and disease.