Chemical Properties of Organic Compounds

Chemical Properties

• Organic vs. Inorganic Compounds: Organic compounds contain carbon-hydrogen bonds (C-H), while inorganic compounds lack C-H bonds. Organic compounds are vital for life.
• Organic compounds are vital to cells: Life as currently understood wouldn't be possible without organic compounds.
• Macromolecules: Large biological molecules encompassing carbohydrates, lipids, nucleic acids, and proteins.
• Carbohydrates: Composed of carbon (C), hydrogen (H), and oxygen (O). Serve as energy and carbon sources for microbes.
  • Monosaccharides: Simple sugars (e.g., glucose).
  • Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).
  • Polysaccharides: Many monosaccharides joined by glycosidic bonds (e.g., glycogen, cellulose, chitin, starch). Some form cell walls (peptidoglycan).
• Lipids: Essential components of biological membranes.
  • Fatty acids: Nonpolar tails, hydrophobic ('water-fearing').
  • Phospholipids: Composed of a glycerol, two fatty acids, and a phosphate group. The phosphate group is hydrophilic ('water-loving'), imbuing the molecules with inherent negative charge. Fatty acids form lipid bilayers in membranes.
• Proteins: Make up 50% of cell dry weight.
  • Amino acids: Linked together by covalent bonds (peptide bonds). 20 different amino acids, each with unique properties (e.g., charge, size) determining protein shape and function.
  • Protein folding results from hydrogen bonds. Bonds between distant amino acids, as well as those between the amino acid chains lead to 3D shape.
  • Denaturation: Disruption of protein structure, resulting in loss of function. Caused by heat.
• Nucleic Acids: Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
  • DNA: Genetic material in most cells; double helix structure.
  • RNA: Intermediate between DNA and protein synthesis in cells; single stranded, but can take other forms.
  • Nucleotides: Monomers of nucleic acids, composed of a sugar, a phosphate group, and a nitrogenous base.

Denaturation

• Denaturation: The conformation of DNA (double helix) results from hydrogen bonding between base pairs.
• DNA function depends on structure: The configuration of the DNA double helix is vital for storing genetic information in a way that organisms can access it.
• Covalent bonds are stronger than hydrogen bonds: Adjacent nucleotides are linked by strong covalent bonds. Hydrogen bonds (weaker) are responsible for bonds between base pairs in DNA. When DNA strands separate, this is called denaturation, typically from heat.
• Protein folding: Proteins have several structural levels (primary, secondary, tertiary, and sometimes quaternary).
• Protein denaturation: The disruption of protein structure (from folding), typically from heat or changes in pH. Leads to a loss of protein function.

Microbiologist Spotlight: Rosalind Franklin

• X-ray crystallography: A technique used to determine the structure of macromolecules (including DNA).
• Photo 51: A crucial X-ray diffraction image of DNA that helped Watson and Crick discover its double helix structure, but Rosalind Franklin was not appropriately credited for her work.
• Nobel Prize: Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine in 1962 for their contributions to DNA's structure; Franklin's contributions were not recognized during her lifetime.