Introduction to Biochemistry

Overview of Biochemistry

• Biochemistry merges chemistry and biology to explore chemical processes in living organisms at molecular levels.
• Emerged in the early 20th century through the intersection of chemistry, physiology, and biology.
• Fundamental to understanding biological processes and the causes of diseases in humans, animals, and plants.

Cellular Foundations

• Cells are the basic structural units of life, requiring constant energy to maintain organization.
• Thousands of chemical reactions occur in cells, requiring precise regulation for life.
• Organisms universally utilize core molecules: carbohydrates (CHO), proteins, lipids, and nucleic acids.
• Genetic instructions for growth and reproduction are encoded in DNA.

Historical Evolution of Biochemistry

• Vitalism in the early 19th century posited life as either "living" or "non-living" matter.
• Friedrich Wohler synthesized urea from inorganic matter in 1828, challenging vitalism.
• Buchners demonstrated that dead cell extracts could catalyze reactions in 1897, leading to the discovery of enzymes.
• Key enzyme-substrate interaction concept proposed by Emil Fischer in the late 1800s.
• The discovery of DNA as genetic material in 1944 and the structure of DNA by Watson and Crick in 1953 solidified biochemistry's foundational role in understanding biology.

Basic Cell Types

• Prokaryotic Cells:

  • Lack membrane-bound nuclei and organelles.
  • DNA is found in the cytoplasm.
  • Ribosomes are small and scattered.
  • Average cell diameter ranges from 0.5 to 10 µm.

• Eukaryotic Cells:

  • Contain membrane-bound nuclei and organelles.
  • Hereditary material is located in the nucleus.
  • Larger ribosomes and an average diameter of 10 to 100 µm.

Metabolism in Biochemistry

• Metabolism includes all chemical reactions that sustain life, categorized into:
  • Anabolism: Energy-requiring biosynthetic activities.
  • Catabolism: Breakdown of molecules to produce energy.
• Enzymes catalyze all metabolic reactions.
• Key functions of metabolism include energy acquisition, molecule synthesis, and waste removal.

Common Biochemical Reactions

• Nucleophilic Substitution: One atom/group replaces another in a molecule.
• Elimination Reactions: Formation of double bonds by removing atoms from molecules.
• Addition Reactions: Two molecules combine into a single product, e.g., hydration forming alcohols.
• Isomerization Reactions: Intramolecular shifts of atoms or groups.
• Oxidation-Reduction Reactions: Electron transfer between donor and acceptor molecules.
• Hydrolysis Reactions: Cleavage of bonds through the addition of water.

Importance of Water in Biochemistry

• Essential for life, constituting 45-75% of human body weight.
• Functions as a solvent for metabolic processes, facilitating absorption, digestion, and temperature regulation.
• Water's polar nature allows it to participate directly in biochemical reactions through hydrogen bonds.

Properties of Water

• Water is a polar molecule, having both positively charged hydrogen atoms and a negatively charged oxygen atom.
• Hydrogen bonds between water molecules create cohesion and adhesion properties.
• Water retains heat energy, supporting body temperature stability.
• Acts as both an acid and a base, contributing to pH balance within organisms.

Amphipathic Compounds

• Characterized by both hydrophobic (nonpolar) and hydrophilic (polar/ionic) groups.
• Form micelles when reaching critical micelle concentration in aqueous environments.
• Micelles consist of hydrophilic exteriors and hydrophobic interiors, stabilized by hydrogen bonds and hydrophobic interactions.
• Examples include soaps, detergents, and phospholipids, which have potential medicinal applications through liposome vesicle formation.

Conclusion

• Understanding biochemistry is crucial for exploring the molecular basis of life, highlighting the importance of biological molecules, cellular structures, and essential reactions in living organisms.