Note Oct 27, 2024 (3)

Review of Biochemistry: Importance of Understanding

  • Understanding biochemistry helps determine effective treatments for dehydration and fluid loss.

Classes of Compounds

Inorganic Compounds

  • Includes water, salts, and many acids and bases.

  • Do not contain carbon.

Organic Compounds

  • Comprises carbohydrates, fats, proteins, and nucleic acids.

  • Contains carbon, usually large and covalently bonded.

  • Both inorganic and organic compounds are essential for life.

Water in Living Organisms

  • Most abundant inorganic compound (60%-80% volume of living cells).

  • Divided into Intracellular Fluid (ICF) vs. Extracellular Fluid (ECF).

  • Properties of Water:

    • High heat capacity

    • High heat of vaporization

    • Polar solvent properties

    • Reactivity

    • Cushioning

Salts and Electrolytes

  • Ionic compounds disassociate into ions in water.

  • Electrolytes conduct electrical currents and play specialized roles in body functions (e.g., sodium, potassium, calcium, iron).

  • Ionic balance is vital for homeostasis.

  • Major salts in the body include NaCl, CaCO3, KCl, calcium phosphates.

Homeostatic Imbalance

  • Electrolyte balance is crucial; disruption affects organ systems.

Acids and Bases

  • Both are electrolytes and ionize/disassociate in water.

  • Acids function as proton donors; bases are proton acceptors.

pH: Acid-Base Concentration

  • pH measures relative free H+ concentration in a solution.

    • Higher H+ increases acidity (pH decreases).

    • Lower H+ increases alkalinity (pH increases).

Acid-Base Homeostasis

  • pH changes interfere with functions and can damage tissues.

  • Blood pH must remain between 7.35–7.45.

  • Regulated by kidneys, lungs, and buffers.

Organic Compounds: Building Blocks

  • Organic compounds contain carbon, excluding CO2 and CO.

  • Key Groups:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

Carbohydrates

  • Sugars and starches; major source of cellular fuel (glucose).

  • Structural molecules: e.g., ribose in RNA.

  • Three classes:

    • Monosaccharides (one sugar)

    • Disaccharides (two sugars)

    • Polysaccharides (many sugars)

Lipids

  • Made from fatty acids and glycerol.

  • Include triglycerides, steroids, vitamins.

  • Functions:

    • Energy storage

    • Insulation

    • Protection

    • Types depend on saturation (saturated vs. unsaturated).

Proteins

  • Composed of C, H, O, N (sometimes S and P).

  • Polymers of amino acids (20 different types).

  • Function depends on structure:

    • Fibrous (e.g., collagen, keratin)

    • Globular (e.g., enzymes, antibodies).

Amino Acids and Protein Structure

  • Peptide bonds link amino acids.

  • Four levels of structure (sequence, alpha/beta folds, 3D structure).

Protein Synthesis

  • Involves transcription (DNA to RNA) and translation (RNA to protein).

  • Types of RNA:

    • mRNA: carries instructions from DNA.

    • tRNA: transfers amino acids during protein synthesis.

    • rRNA: structural part of ribosomes.

Metabolism: Importance

  • Metabolism encompasses all biochemical reactions involving nutrients for energy conversion.

Key Terms

  • Cellular Respiration: Breakdown of glucose for energy.

  • ATP (Adenosine Triphosphate): Main energy carrier.

  • Aerobic vs. Anaerobic: Usage of oxygen in processes.

Cellular Respiration Stages

  1. Glycolysis: Anaerobic breakdown of glucose.

  2. Krebs Cycle: Aerobic reactions producing ATP.

  3. Oxidative Phosphorylation: Generates the most ATP.

Biological Reactions and Energy

  • Anabolism: Building up molecules (requires energy).

  • Catabolism: Breaking down molecules (releases energy).

Overview of Carbohydrate Metabolism

  • Glycolysis converts glucose to pyruvic acid, occurring in all respiration types.

  • Glycogenesis and glycogenolysis manage glucose storage and release.

Lipid Metabolism

  • Lipids function in energy storage and membrane structure.

  • Balance between lipogenesis and lipolysis affects fat build-up.

Cholesterol Management

  • Total Cholesterol: Measure of all cholesterol in blood.

  • HDL (High-Density Lipoprotein): Good cholesterol, lowers heart disease risk.

  • LDL (Low-Density Lipoprotein): Bad cholesterol, contributes to artery blockages.

  • Triglycerides: High levels increase stroke and heart disease risk.

Clinical Relevance of Ketogenesis

  • Produces ketone bodies as an alternative energy source.

  • High ketone levels can lead to metabolic acidosis and dangerously low pH levels.