w1 Molecules of Life

Molecules of Life

  • Organic Compounds

    • Typically large and contain carbon.

    • Known as macromolecules.

    • Key organic compounds include:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

    • Adenosine triphosphate (ATP)

    • Most macromolecules are polymers made by linking monomer units.

Carbohydrates

  • Composed of carbon, hydrogen, and oxygen (CHO).

  • Account for about <3% of body weight.

  • Functions include:

    • Primary energy source (immediate and storage forms).

    • Integral part of nucleic acids.

    • Facilitate cell-cell recognition.

  • Types include:

    • Monosaccharides (single sugars):

    • Examples: Glucose (blood sugar), Fructose (fruit sugar), Galactose (milk sugar), Deoxyribose (in DNA).

    • Disaccharides (two sugars):

    • Example: Sucrose (glucose + fructose), Lactose (glucose + galactose), Maltose (glucose + glucose).

    • Polysaccharides (many sugars):

    • Examples: Glycogen (energy store in humans).

Lipids

  • Comprise fats, oils, sterols; mostly insoluble in water.

  • Contain carbon, hydrogen, and oxygen (less oxygen compared to carbohydrates).

  • Structural components of cells and energy reserves.

  • 12-18% of total body weight in adult males; 18-24% in adult females.

  • Fatty Acids:

    • Saturated: No double bonds between carbon atoms.

    • Unsaturated: Contains one or more double bonds, resulting in a liquid form at room temperature.

  • Triglycerides:

    • Main storage form of fats, providing insulation and protection.

Proteins

  • Make up about 12-18% of body weight.

  • Composed of amino acids linked by peptide bonds.

  • Functions:

    • Structural (collagen, keratin).

    • Regulatory (hormones, neurotransmitters).

    • Movement (actin and myosin in muscles).

    • Immunological (antibodies).

    • Transport (hemoglobin, cholesterol carriers).

    • Catalytic (enzymes).

  • Structural Levels:

    • Primary: Sequence of amino acids.

    • Secondary: Local folding (alpha helices, beta sheets).

    • Tertiary: Overall 3D shape of protein.

    • Quaternary: Complex of multiple polypeptide subunits.

Enzymes

  • Proteins that act as biological catalysts.

  • Increase reaction rates without being consumed in the process.

  • Highly specific in action, can catalyze reactions up to 10 billion times faster.

  • May require cofactors (minerals) or coenzymes (vitamins).

Nucleic Acids

  • Two forms:

    • DNA: Stores genetic information, structure is a double helix formed from nucleotides (composed of deoxyribose, phosphate, nitrogenous bases A, T, G, C).

    • Base pairing rules: Adenine pairs with Thymine, Guanine pairs with Cytosine.

    • RNA: Involved in protein synthesis, supports the transfer of genetic instructions from DNA.

Adenosine Triphosphate (ATP)

  • Main energy unit in living organisms.

  • Hydrolysis of ATP releases energy through the action of the enzyme ATPase, producing ADP and a free phosphate group.

Summary

  • Organic compounds are carbon-containing substances that provide structure, energy, genetic information, and cellular regulation.

  • Four main organic molecules are carbohydrates, lipids, proteins, and nucleic acids, with ATP as the primary source of cellular energy.