chap 1

• Living systems can self-replicate through simple division in bacteria and sexual reproduction in plants and animals
• Inanimate matter moves towards a condition of increasing disorder or maximum entropy
• Distinctive Properties of Living Systems

  • Organisms are complicated and highly organized
  • Biological structures serve functional purposes
  • Living systems are actively engaged in energy transformations
  • Living systems have a remarkable capacity for self-replication
  • Living systems have a high degree of fidelity
  • H, O, C, and N make up 99+% of atoms in the human body
• The ability of H, O, C, and N to form covalent bonds by electron-pair sharing unites them and makes them appropriate for the chemistry of life
• Formation of macromolecules

  Inorganic precursors are converted to metabolites, which are intermediates in cellular energy transformation and biosynthesis of building blocks like amino acids, sugars, nucleotides, fatty acids, and glycerol. These building blocks form macromolecules like proteins, polysaccharides, polynucleotides (DNA and RNA), and lipids
• C can form covalent bonds with itself and has a tetrahedral shape, allowing for a variety of linear, branched, and cyclic compounds
• “…everything that living things do can be understood in terms of the jigglings and wigglings of atoms.” - Richard P. Feynman
• Energy transformations in Living Systems

  ATP and NADPH are special energized biomolecules that drive biosynthesis, movement, osmotic work against concentration gradients, and light emission
• Living organisms extract free energy from the environment and export entropy in the form of heat
• H, O, C, and N are the atoms that make up 99+% of the human body
• C, N, and O can share two electron pairs to form double bonds within biomolecules, enhancing their chemical versatility
• Inorganic precursors

  • Water (H2O)
  • Carbon dioxide (CO2)
  • Ammonium (NH4+)
  • Nitrate (NO3-)
  • Dinitrogen (N2)
• Supramolecular complexes

  • Multi-functional enzyme complexes
  • Ribosomes
  • Chromosomes
  • Cytoskeleton
• The unit of life is the cell
• Formation of macromolecules

  1. Protein

  2. Polysaccharides

  3. Polynucleotides (DNA and RNA)

  4. Lipids
• Hydrophobic interaction leads to the creation of discrete volumes or compartments within cells
• Some biomolecules must contain the information or "recipe" of life
• An orderly mechanism for abstracting energy from the environment must exist to drive life processes
• Biological macromolecules are informational
• Weak forces maintain biological structure and determine biomolecular interactions
• Other biomolecules must translate the information for the synthesis of organized structures essential to life
• Membranes define the boundaries of cells and organelles
• Non-covalent interactions among macromolecules result in the formation of supramolecular complexes
• There is a necessity for information and energy in the maintenance of the living state
• Biosynthesis of various sets of building blocks

  1. Amino acids

  2. Sugars

  3. Nucleotides

  4. Fatty acids

  5. Glycerol
• The membranes of organelles differ from one another with each having a characteristic protein and lipid composition tailored to the organelle's function
• Biological macromolecules and their building blocks have a "sense" or directionality
• Biomolecules have characteristic three-dimensional architecture
• Hydrogen bonds

  • Form between a hydrogen atom covalently bonded to an electronegative atom and a second electronegative atom
  • Cylindrically symmetrical and highly directional, forming straight bonds between donor, hydrogen, and acceptor atoms
• Weak Forces


  • Maintain Biological Structure and Determine Biomolecular Interactions
• The defining concept of biochemistry is “molecular recognition through structural complementarity”
• Biological function is achieved through mechanisms based on structural complementarity and weak chemical interactions
• Ionic interactions may involve

  • Ions
  • Permanent dipoles
  • Induced dipoles
• Cells cannot tolerate reactions with large energy releases or generate large energy bursts to drive energy-requiring processes
• Living systems are restricted to a narrow range of physical conditions due to weak forces governing biomolecular interactions
• Cellular metabolism consists of ordered reaction pathways by which biological energy transformations are accomplished
• Supramolecular complexes occur due to recognition and interaction between various macromolecular components governed by weak forces
• Ionic interactions

  • Attractive forces between oppositely charged structures
  • Electrical charge is radially distributed, lacking directionality of hydrogen bonds or precise fit of van der Waals interactions
• Hydrophobic interactions


  • Result from water's strong tendency to exclude nonpolar groups or molecules
  • Without these interactions, water's entropy is raised
• Specific molecular recognition mechanisms

  • A protein recognizes its specific metabolite