Unit 1

• Biological organization


  Hierarchical nature of, all living organisms composed of smaller and smaller non-living building blocks
• Cells


  Smallest units of biological organization that retain the characteristics of life
• Composition of cells


  Highly-organized assemblies of non-living molecules, each containing one or more types of atoms
• Elements in human body

  • Oxygen (65%)
  • Carbon (18%)
  • Hydrogen (10%)
  • Nitrogen (3%)
  • Other (4%)
• Elements in atmosphere


  • Nitrogen (78%)
  • Oxygen (21%)
  • Other (1%)
• Atom


  Composed of protons, neutrons, and electrons

  
• Isotopes


  Versions of atoms of a particular element with alternate numbers of neutrons in their nuclei
• Stable isotopes


  Do not undergo radioactive decay
• Unstable isotopes


  Undergo radioactive decay at a relatively constant rate
• Electron shells


  Concentric shells surrounding the nucleus, electrons fill in order of increasing energy

  
• Electron configuration


  Number of electrons in each electron shell

  
• Chemical bonds


  Occur when two atoms, interacting through their valence electrons, form an association that is energetically more stable than it is for the atoms to remain apart
• Ionic bonds


  Occur between metal and nonmetal atoms, where one atom donates an electron to the other
• Covalent bonds


  Occur when atoms fill their valence shells by sharing one or more pairs of electrons
• Electronegativity


  The attraction of an atom's nucleus for the shared electrons in a covalent bond
• Nonpolar covalent bond


  Electrons are shared equally between atoms
• Polar covalent bond


  Electrons are shared unequally between atoms

  
• Polarity of molecules


  Determined by the shape and arrangement of polar and nonpolar covalent bonds

  
• Properties of water


  • Solid water (ice) less dense than liquid water
  • Excellent solvent for polar molecules and ions
  • Strong surface tension due to cohesion between molecules
  • Adhesion facilitates capillary action
  • Large specific heat value
• Aqueous solution


  Occurs when a solid chemical dissolves in water, the ions or molecules are the solutes and the water is the solvent
• pH scale


  Reflects the concentration of hydrogen ions (H+) in an aqueous solution
• Acids


  Contain high concentrations of H+ ions in solution, capable of adding these ions to biological molecules
• Bases


  Contain low concentrations of H+ ions in solution, capable of stealing these ions from biological molecules
• Carbon atom


  Second most common element in living organisms, can form four covalent bonds
• Organic molecules


  Carbon-containing matter found in living organisms
• Functional groups


  Regular patterns of atoms bonded to carbon in organic molecules
• Organic macromolecules


  Long chains of carbon atoms with incredible structural and functional diversity
• Living organisms are composed of four types of carbon-based (organic) macromolecules
• Four types of organic macromolecules

  • Lipids
  • Carbohydrates
  • Proteins
  • Nucleic acids

  
• Organic macromolecules are polymers composed of subunits, or building blocks, called monomers
• Organic polymers are synthesized

  1. Linking together monomers with special types of covalent bonds

  2. These "joining" processes are called condensation reactions

  3. Each reaction yields a single molecule of water

  
• Organic polymers are degraded (broken down)


  1. Severing the covalent bonds that link the monomers

  2. These "breakdown" processes are called hydrolysis reactions

  3. Each reaction uses a single molecule of water

  
• Lipid


  A carbon-containing biological molecule that is largely nonpolar and hydrophobic

  
• Fatty acid


  A hydrocarbon chain that is bonded to a carboxylic acid (COOH) functional group

  
• Most fatty acids have an even number of carbon atoms - they are synthesized by joining two-carbon acetyl groups

  
• Saturation (in lipid biochemistry)


  The degree to which the carbon atoms in a fatty acid are linked to hydrogen atoms

  
• Saturated fatty acid


  • Stearic acid

  
• Unsaturated fatty acid


  • Oleic acid

  
• Saturation level of a fatty acid

  Affects its chemical properties at room temperature
• Four important types of cellular lipids

  • Fats (triglycerides)
  • Phospholipids
  • Steroids
  • Waxes