Biology Workbook - Theme 2: Organization - Organic Compounds

THEME 2: ORGANIZATION

2.2 Organic Compounds

Overview of Organic Molecules

• Organic molecules are created when different elements combine with carbon atoms.

• These combinations include special groups that act like "instruction manuals". They determine the functions and behaviors of the molecule in living organisms.

• Organic molecules can be synthesized naturally by living organisms (plants, animals) or artificially in laboratories.

• Common examples: carbohydrates, lipids, proteins, nucleic acids, amino acids.

• Main functions: serve as fundamental components of cells and regulate numerous biological activities.

• Comparison to inorganic molecules:

  • Organic molecules are larger and more complex than inorganic molecules (e.g., water).

• Macromolecules:

  • Large organic molecules including lipids, carbohydrates, proteins, and nucleic acids, termed biomolecules.

  • Polymers: Macromolecules formed by chains of repeating units known as monomers.

• Covalent Bonds: Linkage that forms between monomers during polymer synthesis.

Dehydration Synthesis

• Definition: The process of building large molecules from smaller monomers, which requires energy and enzymes.

• Process Characteristics:

  • A water molecule is removed during the reaction.

  • The number of water molecules produced corresponds to the number of bonds formed between monomers.

  • Enzymes play a crucial role in facilitating this synthesis process.

Hydrolysis

• Definition: The process in which large molecules are broken down into their constituent monomers by adding water.

• Characteristics:

  • It is the reverse of dehydration synthesis.

  • Each covalent bond broken requires a molecule of water, with the hydroxyl group attaching to one monomer and the hydrogen atom to the other.

• Example in the Human Body: Digestion of food.

• General Formula of Hydrolysis: $n ext{ (monomer)} + ext{ Polymer} + (n-1) ext{ H}_2 ext{O} ightarrow n ext{ (monomer)}$.

  • Here, enzymes are still required to assist in the reaction.

CARBOHYDRATES

Composition and Structure

• Carbohydrates are organic compounds primarily made of:

  • Carbon (C)

  • Hydrogen (H)

  • Oxygen (O)

• Sometimes include nitrogen (N) atoms.

• Functions:

  • Major sources of energy for living organisms.

• Types:

  • Monosaccharides: Single sugar units.

  • Disaccharides: Composed of two monosaccharides.

  • Polysaccharides: Long chains of monosaccharides.

Monosaccharides

• General molecular formula: C_n_H_{2n}O_n.

• Types based on carbon count:

  • Triose: 3 carbon atoms.

  • Tetrose: 4 carbon atoms.

  • Pentose: 5 carbon atoms.

  • Hexose: 6 carbon atoms.

  • Heptose: 7 carbon atoms.

• Pentoses:

  • Components of nucleic acids (Ribose - RNA, Deoxyribose - DNA).

  • Ribose regulates metabolic activities and cell communication.

• Hexoses:

  • Variability in structural isomerism leads to numerous structural forms despite having the same formula.

  • Most significant hexoses: glucose, fructose, galactose.

• Glucose:

  • Most common hexose, serving as energy source in cells and referred to as blood sugar or grape sugar.

  • Critical for cellular metabolism and stored as glycogen in animals or starch in plants.

Disaccharides

• Formed from two monosaccharides through dehydration synthesis with a glycosidic bond.

• Process:

  • Two monomers combine, eliminating one water molecule.

• Common disaccharides:

  • Maltose: Glucose + Glucose (malt sugar).

  • Sucrose: Glucose + Fructose (table sugar).

  • Lactose: Glucose + Galactose (milk sugar).

• Hydrolysis of Disaccharides:

  • Digestive enzymes break disaccharides into monosaccharides for metabolic use.

Polysaccharides

• Long-chain organic molecules formed by the linkage of numerous monosaccharides.

• Typically composed of hundreds of glucose units, but may include other types of sugars.

• Characteristics:

  • Less soluble in water and not sweet.

• Types of Polysaccharides:

  • Storage Polysaccharides: Include glycogen and starch used to store glucose.

  • Structural Polysaccharides: Include cellulose (plants) and chitin (insects and fungi).

Storage Polysaccharides

• Glycogen:

  • Synthesized in liver and muscle cells for energy during exercise.

  • Regulates blood sugar levels in the liver.

• Starch:

  • Produced by plants during photosynthesis stored in seeds, tubers, and roots.

• Structural similarities to glycogen.

Structural Polysaccharides

• Cellulose:

  • Key structural component of plant cell walls, providing mechanical support.

  • Composed of glucose polymers; largely non-digestible by humans but essential in human diet as fiber.

• Chitin:

  • Contains nitrogen, found in the exoskeletons of insects and crustaceans and fungal cell walls.

  • Used in medical applications for biocompatible sutures.