Chemical foundations

• Major elements found in living organisms

  • Carbon
  • Oxygen
  • Nitrogen
  • Phosphorus
• Significance of carbon in biomolecules


  Carbon is versatile, forms strong bonds, and is the center of organic molecules
• Macromolecules


  Polymers with molecular weight > 5,000
• Macromolecules


  • Proteins
  • Nucleic acids
  • Polysaccharides
• Proteins in cells


  • Function as enzymes, structural elements, signal receptors, and transporters
• Functions of nucleic acids


  • Store and transmit genetic information, have catalytic and structural roles
• Functions of carbohydrates in cells


  • Function as energy stores, structural elements, and recognition molecules
• Functions of lipids in living organisms


  • Serve as energy stores, structural components of membranes, pigments, and signaling molecules
• Covalent bonds


  Strong bonds involving sharing of electrons
• Non-covalent bonds


  Weaker interactions
• Covalent bonds have a high bond energy of 100 kcal/mol
• Covalent bonds are a major bond in small biomolecules
• Covalent bonds


  Link monomers to form polymers
• Main types of non-covalent bonds

  • Hydrogen bond
  • Hydrophobic interactions
  • Ionic interactions
  • van der Waals interactions
• Hydrogen bond


  Occurs between hydrogen and oxygen, nitrogen, or sulfur
• Hydrophobic interaction


  Interaction between hydrophobic molecules where water tries to cage the molecule
• Ionic interaction


  Interaction between atoms and charged groups
• van der Waals interaction


  Weak and transient interaction between permanent and/or induced dipoles
• Configuration


  1. D arrangement of atoms in a molecule
• Stereoisomer


  Molecule with the same chemical bonds but different 3-D arrangement
• Factors conferring a molecule's configuration

  Presence of double bonds or chiral centers
• A molecule with 4 chiral centers can have 16 stereoisomers
• D and L system in biomolecules


  D - carbohydrates, L - amino acids
• Stereospecificity


  Property of enzymes and proteins to distinguish between stereoisomers
• Stereospecific biomolecular interactions


  • Enzyme + reactant
  • Hormone + receptor
  • Antigen + antibody