Biochemistry

1. Biomolecules

a. Carbohydrates

  • Function: Primary energy source.
  • Types:
    • Monosaccharides (e.g., glucose, fructose)
    • Disaccharides (e.g., sucrose, lactose)
    • Polysaccharides (e.g., starch, glycogen, cellulose)

b. Proteins

  • Function: Enzymes, structural support, transport, signaling.
  • Made of: Amino acids (20 standard types).
  • Structure:
    • Primary: Sequence of amino acids
    • Secondary: Alpha helices and beta sheets
    • Tertiary: 3D folding
    • Quaternary: Multiple protein subunits

c. Lipids

  • Function: Energy storage, membrane structure, signaling.
  • Types:
    • Triglycerides (fats/oils)
    • Phospholipids (membranes)
    • Steroids (cholesterol, hormones)

d. Nucleic Acids

  • Function: Genetic information storage and transmission.
  • Types:
    • DNA (Deoxyribonucleic acid)
    • RNA (Ribonucleic acid)
  • Building Blocks: Nucleotides (A, T/U, C, G)

2. Enzymes

  • Definition: Biological catalysts that speed up chemical reactions.
  • Properties:
    • Highly specific
    • Not consumed in the reaction
    • Affected by pH, temperature, inhibitors
  • Kinetics: Michaelis-Menten equation describes enzyme activity.
  • Inhibition: Competitive, non-competitive, uncompetitive

3. Metabolism

a. Catabolism

  • Breakdown of molecules to release energy.
  • Examples:
    • Glycolysis: Glucose → Pyruvate
    • Krebs Cycle (TCA): Produces ATP, NADH
    • Beta-oxidation: Fatty acids → Acetyl-CoA

b. Anabolism

  • Building complex molecules from simpler ones.
  • Examples:
    • Protein synthesis
    • DNA replication
    • Gluconeogenesis (glucose from non-carbs)

4. Bioenergetics

  • Study of energy flow in biological systems.
  • ATP (Adenosine Triphosphate) is the energy currency.
  • Processes like oxidative phosphorylation in mitochondria generate ATP.

5. Hormones and Signal Transduction

  • Hormones (e.g., insulin, glucagon) regulate metabolism.
  • Signal transduction pathways transfer signals from outside the cell to inside using receptors and second messengers (like cAMP, IP₃).

6. pH and Buffers

  • Biological systems maintain a narrow pH range.
  • Buffers (e.g., bicarbonate buffer system) resist changes in pH.

7. Molecular Biology Basics

  • Central Dogma: DNA → RNA → Protein
  • DNA replication, transcription (DNA → RNA), translation (RNA → protein)

8. Clinical Biochemistry Applications

  • Blood glucose testing (diabetes)
  • Liver function tests (ALT, AST)
  • Kidney function tests (urea, creatinine)
  • Lipid profile (cholesterol, triglycerides)
  • Enzyme assays (e.g., amylase in pancreatitis)