bio unit 2

• Molecular biology


  Explains living processes in terms of the chemical substances involved
• Carbon atoms


  • Can form four covalent bonds allowing a diversity of stable compounds to exist
  • Form the basis of organic life due to their ability to form large and complex molecules via covalent bonding
• Life is based on carbon compounds

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids

  
• Metabolism


  The web of all the enzyme-catalyzed reactions in a cell or organism
• Anabolism


  The synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions
• Catabolism


  The breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers
• Urea


  • A compound that is produced by living organisms but can also be artificially synthesized
• Organic chemistry


  The study of the properties and structures of organic compounds
• Organic compound


  A compound that contains carbon and is found in living things
• Not all carbon compounds are organic (e.g. CO2, urea)
• Carbon-carbon bonds


  • Are strong and stable due to their covalent bond
  • Allow carbon to form an almost infinite number of compounds including long carbon chains
  • No other element can bond like this
• Four principle groups of carbon compounds

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids

  
• Polymers


  Complex macromolecules commonly made of smaller, recurring sub units called monomers
• Carbohydrates, nucleic acids and proteins are all polymers comprised of monomers, but lipids do not contain recurring monomers

  
• Metabolic pathways


  Show a sequence of chemical reactions undergone by a compound or class of compounds in a living organism, most consist of chains of reactions but there are also some cycles
• Metabolic reactions


  Can be classified as anabolic or catabolic
• Anabolic reactions include photosynthesis and cellular respiration along with the synthesis of RNA and proteins
• Catabolic reactions include glycolysis
• Condensation


  Makes a bond, releases water, and is an anabolic reaction
• Hydrolysis


  Breaks a bond, requires water, and is a catabolic reaction

  
• Condensation is used to synthesize all important biological macromolecules (carbohydrates, proteins, lipids, nucleic acids) from their simpler monomers
• Hydrolysis is used to split polymers into smaller monomers by breaking a bond by using water
• Vitalism


  A belief that organic molecules can only be synthesized by living things
• In 1800 urea was produced from inorganic chemicals proving organic molecules don't have to be synthesized by living things
• Water molecules


  Are polar and hydrogen bonds form between them
• Hydrophilic


  Molecules that are attracted to water (water loving)
• Hydrophobic


  Molecules that hate water (water hating)
• Amphipathic


  A molecule having both hydrophilic and hydrophobic parts
• Cohesion


  An attraction between molecules of the same type
• Cohesion in water


  • Allows some organisms to rest or move on top of water's surface
  • Allows water to move as a column (group of water molecules) through the stem of plants
• Adhesion


  An attraction between two unlike molecules
• Adhesion of water


  • Water moves up the stems of plants because it is attracted to the sides of the stem
• Water as a solvent

  Can dissolve any substance that contains charged particles (ions) or electronegative atoms (polarity)
• Water as a solvent

  • The phloem (part of the plant stem) carries a fluid made of water and lots of dissolved substances
  • Blood carries a lot of dissolved nutrients in the plasma to different tissues in the body
• Water's thermal properties


  • High specific heat capacity (amount of energy required to raise the temperature)
  • Can absorb a lot of energy before becoming too hot
  • Must lose a lot of energy to drop in temperature
• Water's thermal properties


  • Cells can withstand a lot of heat energy releases from their metabolic reactions without boiling away
  • Sweat on the skin can absorb a lot of heat energy before it evaporates, cooling an organism
  • Aquatic organisms can't survive extreme temperature changes
  • Plants have openings in their leaves called stomata to let vaporizing water out in order to cool down
• Differences in thermal properties between water and methane

  Arise from differences in polarity between the molecules
• Water absorbs more heat before changing state compared to methane
• Monosaccharide monomers


  Are linked together by condensation reactions to form disaccharides and polysaccharide polymers

  
• Fatty acids


  Can be saturated, monounsaturated or polyunsaturated