Unit 1 Chemistry of Life

• Water


  Unique compared to other molecules: it can be a gas, liquid and a solid, and is the only common substance on earth that is able to exist in the natural environment in all three states of matter
• Water's structure


  • Made up of two hydrogen molecules and one oxygen molecule connected through a single covalent bond
  • Oxygen is more electronegative than hydrogen, so the electrons are closer to oxygen than hydrogen (Polar covalent bond)
  • This makes water a polar molecule with unevenly distributed charge
  • Oxygen has two regions of partial negative charge while each hydrogen has a partial positive charge
• Hydrogen bonds


  • The partial areas of positive charge in a water molecule are attracted to areas of partial negative charge in another molecule forming a hydrogen bond
  • Hydrogen bonds form between hydrogen and oxygen/fluorine/nitrogen
  • Each water molecule can form up to four hydrogen bonds
• Cohesion


  When hydrogen bonds form between molecules of the same type
• Adhesion


  When hydrogen bonds form between two different types of molecules
• Emergent properties of water


  • Surface tension
  • High solvency
  • Water is more dense as a liquid than as a solid
  • Water has a high specific heat capacity
• Surface tension


  1. Result of an increase of hydrogen bonding at the surface of water

  2. Allows some insects/aquatic organisms to walk on water

  3. Allows aquatic organisms to settle on the surface of water for sunlight so that photosynthesis can take place
• High solvency


  Water is an excellent versatile solvent because of its polarity
• Our cells/bodies are made up of 70% water
• Water is frozen


  Hydrogen bonding between four neighboring water molecules
• Liquid water


  Hydrogen bonds constantly break and reform
• Ice floats on top of water, insulating the water below and protecting any organisms living in the body of water by stopping the water below from freezing
• Water has a high specific heat capacity


  • Allows it to absorb large quantities of heat, resisting sudden changes in temperature
  • Other covalently bonded liquids require only half the amount of energy to raise 1 degree celsius
  • The hydrogen bonds that link water molecules absorb heat without changing temperatures significantly
  • Heat must be absorbed to break the hydrogen bonds, or it needs be released to form hydrogen bonds
  • Water also holds on to its heat, so its temperature tends to fall more slowly than other liquids
• It takes 1 cal to raise 1g of water to raise the temperature up 1C, and it also takes 1 cal to bring down the temperature of 1g by 1C
• Compared to other substances, water has a much higher specific heat, and this allows it to be a more stable habitat for wildlife
• Water absorbs heat in daytime during the summer


  Only goes up a few degrees
• Water releases heat slowly during the night and winter

  Warms the air
• This capability of water allows it to moderate the temperature of the air in coastal areas
• This helps organisms maintain/regulate their internal temperature
• Capillary action


  1. Cohesion due to hydrogen bonding allows the transport of water and dissolved nutrients against gravity in plants

  2. As water evaporates from a leaf, hydrogen bonds cause the water to be pulled upwards from the roots, adhering to the walls of xylem vessels against gravity and pulling other water molecules too

  3. Adhesive properties allow water to be attracted to the walls of xylem vessels

  4. Cohesive properties allow other water molecules to follow the water molecules attracted to the xylem vessels
• Capillary action allows plants to receive water from the ground
• Wind also plays a role with transpiration, spreading the water molecules throughout the plant
• High heat evaporation


  • Water has a higher heat evaporation because hydrogen bonds must be broken first
  • This property is emergent from the strength of the hydrogen bonds
  • The hydrogen bonds are broken down to change from a liquid and enter the form of water vapor
• Evaporation cooling


  When animals sweat or are splashed, their body heat is used to vaporize the water, cooling them down
• On a global scale, vaporization


  Helps moderate Earth's climate with oceans absorbing a large amount of solar heat, and the vapor released moves upwards and forms rain as it condenses
• Evaporation of water from the leafs of a plant


  Helps its tissues from becoming too warm under the sunlight
• High humidity on a hot day

  Causes discomfort because the high concentration of water vapor in the air inhibits the evaporation of sweat from the body
• Vocabulary


  • Calorie: The amount of heat energy needed to raise the temperature of 1g of a substance 1 degree celsius
  • Aqueous Solution: A solution where the solute is dissolved in water
  • Hydration shell: the sphere of water molecules around each dissolved ions
  • Dissipates: to cause energy to be lost in the form of heat
  • Transiently: Hydrogen bonds are constantly breaking and reforming (temporary)
  • Heat of vaporization: the quantity of heat that a liquid must absorb for 1 gram to change from a liquid into a gaseous state
• The 4 main Macromolecules

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic Acids
• All living things use these four macromolecules
• Macromolecules


  Can also be referred to as polymerase due to their large size
• Carbohydrates


  Act as the main source of energy for living things
• Building blocks (monomers) of carbohydrates

  • Glucose
  • Fructose
  • Galactose
• Types of carbohydrates


  • Monosaccharides (simple sugars)
  • Disaccharides (2 monosaccharides joined)
  • Oligosaccharides (3-10 monosaccharides joined)
  • Polysaccharides (10+ monosaccharides joined)
• Disaccharides


  Formed when 2 monosaccharides are joined using a glycosidic bond (covalent bond)
• Examples of disaccharides


  • Lactose (glucose + galactose)
  • Sucrose (glucose + fructose)
  • Maltose (glucose + glucose)
• Dehydration synthesis


  1. The process of linking molecules together through the removal of water, and use a covalent bond to be attached to each other

  2. When a bond forms between 2 monomers each monomer contributes a part of a water molecule: one monomer provides the hydroxyl group (-OH), and the other monomer provides with hydrogen (-H)

  3. When this process is repeated with monomers it forms a chain, which then forms a polymer
• 1. 4 glycosidic linkage


  Joining the 1st carbon ring (atom carbon one) to the fourth carbon ring in the second monosaccharide (atom carbon four) forming a bond by removing H2O
• Hydrolysis


  1. The process of breaking down the bond between monomers, by adding water

  2. It is the reverse action of dehydration synthesis

  3. It's when the hydrogen of a water molecule attaches to a monomer and the hydroxyl group of water attaches to another monomer
• Digestion: The organic material of our food is way too big to absorb into cells as they are polymers. Using hydrolysis, they are broken down into monomores absorbed into the bloodstream