HBS109: Human Structure and Function Study Notes

HBS109: Human Structure and Function Study Notes

Chemical Level of Body Organisation

Water (H2O)

  • Essential for Life

    • Water is fundamental for biological processes.

  • Unique Properties of Water

    • Solubility: Water can dissolve both inorganic and organic molecules, forming solutions.

    • Reactivity: Water can participate in chemical reactions or act as a medium for these reactions.

    • Notable terms:

    • Hydrophilic: Substances that dissolve in water.

    • Hydrophobic: Substances that do not dissolve in water.

  • Additional Properties:

    • High heat capacity: Water can absorb or release a significant amount of heat without a large change in temperature, helping organisms maintain thermal homeostasis.

    • Lubrication: Water helps reduce friction between surfaces in the body, such as joints.

Acids, Bases, Salts and the pH Scale

Acids, Bases, and Salts

  • Acids

    • Definition: Acids release H+ ions into solution (aqueous).

    • Example: Hydrochloric acid (HCl) dissociates into H+ and Cl-.

    • Important suffix: “..ate” (e.g., lactic acid vs. lactate).

  • Bases

    • Definition: Bases remove H+ from solution.

    • Example: Sodium hydroxide (NaOH) dissociates into Na+ and OH-.

  • Salts

    • Definition: Salts are compounds made of ions other than H+ and OH-.

    • Example: Sodium chloride (NaCl).

pH and H+ Concentration

  • Water Dissociation:

    • H2O ↔ H+ + OH-

  • pH Definition:

    • pH is a measure of H+ concentration in a solution.

    • Neutral pH: 7 (H+ = OH-).

    • Acidic pH: < 7 (H+ > OH-).

    • Basic pH: > 7 (H+ < OH-).

  • pH of Blood:

    • Normal pH range: 7.35 - 7.45.

    • H+ concentration: [H+] = 1 x 10^-7 mol/L.

    • Molarity Reference: 1 mol = 6.022 x 10^23 molecules.

  • pH Scale Representation:

    • H+ Concentration: 10^-1 to 10^-14 mol/L (increasing acidity to alkalinity).

    • Categories:

    • Urine, Pure Water

    • Increasing concentration of H+: 0.1, 0.01, 0.001, etc.

Buffers

  • Definition: Buffers are compounds that help balance the pH of a solution by either adding or removing H+ ions.

    • Equation Example: HCl + NaOH → H2O + NaCl (not ideally illustrative)

    • Another ionization example: H2CO3 ↔ H+ + HCO3-.

Biological Macromolecules

Carbohydrates

  • Composition:

    • Ratio of Carbon : Hydrogen : Oxygen = 1:2:1 (CHO’s), commonly includes sugars and starches.

  • Types of Carbohydrates:

    • Monosaccharides:

    • Example: Glucose (C6H12O6).

    • Disaccharides:

    • Example: Sucrose (table sugar).

    • Polysaccharides:

    • Examples: Starch, glycogen.

Lipids

  • Composition:

    • Ratio of Carbon : Hydrogen = 1:2 (with significantly less oxygen than carbohydrates).

  • Characteristics:

    • Include fats, oils, waxes.

    • Serve as important structural elements of cells.

    • Provide twice as much energy as carbohydrates.

  • Types of Lipids:

    • Fatty Acids

    • Eicosanoids

    • Glycerides

    • Steroids

    • Phospholipids/Glycolipids.

Proteins

  • Composition:

    • Carbon : Hydrogen : Oxygen : Nitrogen = (CHONs).

  • Functions:

    • Support: Provides structure and strength.

    • Movement: Facilitate muscular contraction.

    • Transport: Serve as carrier molecules in the body.

    • Buffering: Maintain pH balance.

    • Metabolic Regulation: Act as enzymes.

    • Coordination and Control: Function as hormones.

    • Defence: Protect against pathogens (both external and internal).

  • Protein Structure:

    • Composed of long chains of amino acids.

    • Each amino acid comprises:

    • Central carbon atom

    • Hydrogen atom

    • Amino group

    • Carboxylic acid

    • R group (side chain).

Protein Structural Levels

  • Primary Structure:

    • Definition: A single chain of amino acids.

  • Secondary Structure:

    • Definition: Folding into helix or pleated sheets.

  • Tertiary Structure:

    • Definition: Three-dimensional coiling and folding of the chain.

  • Quaternary Structure:

    • Definition: Interaction of two or more polypeptide chains to form a complex.

Nucleic Acids

  • Composition:

    • Carbon : Hydrogen : Oxygen : Nitrogen : Phosphorus (CHONPs).

    • Includes DNA and RNA.

  • Building Blocks:

    • Nucleotides comprise:

    • Nitrogenous base.

    • Sugar group.

    • Phosphate group.

  • Nitrogenous Bases:

    • Five types: Adenine (A), Guanine (G), Cytosine (C), Thymine (T - in DNA), Uracil (U - in RNA only).

Nucleic Acid Structure

  • DNA:

    • Structure consists of a pair of nucleotide chains.

    • Base pairing rules: A pairs with T and G pairs with C.

  • RNA:

    • Structure: A single chain of nucleotides.

    • Overall shape is determined by the sequence of nucleotides.

High Energy Compounds

  • Definition:

    • Any organic compound with a phosphate (PO4^3−) group attached is considered a high energy compound.

  • Role:

    • Involved in the storage or transfer of energy.

    • Examples: Adenosine triphosphate (ATP) and creatine.

    • Further discussions on metabolism to follow.