Unit 1 Biomolecules

• Hydrogen bond

  Weak bonds between a slightly positively charged hydrogen atom in one molecule and a slightly negative charged atom in the other molecule
• Dipolar 


  Having a positive and negative pole as a result of the uneven distribution of electrons within it
• Metabolite


  A substance involved in a metabolic reaction
• Solvent 


  A liquid that other substances dissolve in
• Solute 


  A substance that's dissolved in another substance
• Specific Heat Capacity


  The heat energy needed to raise the temperature of a 1g substance by 1°C
• Latent Heat of Vaporisation


  Heat energy needed to change water to water vapour
• Cohesion 


  Attraction between molecules of the same type (two water molecules)
• Adhesion


  Attraction between molecules of different type (water molecule and wall of the xylem)
• Surface Tension


  Measure of how hard it is to break the surface of a liquid
• Ion


  Atom with positive or negative charge from losing or gaining electrons
• Water a Dipolar Molecule 


  2 hydrogen atoms and 1 oxygen atom (electrons not shared equally in covalent bonding - oxygen has greater electronegativity so greater pull on e) and has both neg and post poles
• Water + Density 


  Most dense at 4°C

  • Freezes then H bonds form rigid lattice to hold molecules further apart
  • Ice less dense than water, molecules spread out in a crystal structure so ice floats
  • Ice floats so forms insulating layer as a barrier to cold for survival of aquatic organisms
• Water + Metabolite 


  Medium for enzyme-catalysed reactions - essential to maintain metabolism

  • Metabolic reactions occur faster in solution
  • Water used in hydrolysis to break down complex molecules + formed in condensation (?synthesis)
• Water + Universal Solvent 


  Dissolves more substances than any other liquid due to polar nature (mineral ions dissolved in water and absorbed by organisms)
• Water + Cohesion/Adhesion/Surface Tension


  S.T - interference between water and air

  Water molecule on surface forms H bond with molecules around and below but NOT with air molecules above.

  Unequal distribution of bonds makes S.T, makes water contract and form tough film/skin (due to cohesive forces)

  • All 3 forces important to transport water through the xylem/ drainage of tears through tear duct/for insects to stay afloat
• Water + HSHC 


  Has thermal stability from hshc

  Many h bonds need lots of energy to break - water gain or lose lots of energy without changing temp

  Little variation in temp = buffer against sudden temp changes (in organisms body or in water surrounding)

  Specific Heat Capacity of Water = 4190Jkg-10°C
• Water + High Latent Heat of Vaporisation 


  Lot of H bonds need lots of energy to evap 1g of water

  Sweating effective to cool the body - Body temp above normal sweat secreted

  water molecules in sweat gain energy until it breaks free

  bonds turn into water vapour

  sweat evaporates heat energy removed from sweat on body

  loss of energy cools surface of the skin
• Water + Transparency 


  Allows light to pass through for photosynthesis in aquatic plants
• Inorganic Ions


  Occur in the solution of the cytoplasm/body fluids of organisms - in high or low concentrations

  Ionic compounds - positively charged atom + negatively charged atom (sodium and chlorine)

  strong electrostatic forces

  Dissolved in water so sodium ion (+) bonds with oxygen atom (-) and chloride (-) bonds with hydrogen (+)

  Ions separate and surrounded by water - keep particles in solution so sodium chloride readily dissolves in water
• Hydrocarbons 


  Molecules that only contain Hydrogen and carbon atoms
• Triglyceride 


  Lipid made from glycerol molecule bonded to 3 fatty acid molecules
• Fatty acids


  Carboxylic acid joined to hydrocarbon tail (tail vary length)
• Saturated Fatty Acid 


  Fatty acid that does NOT have double bonds between carbon atoms

  max number of H are bonded to fatty acid

  Saturated with hydrogen> molecules align readily so fats are solid at room temp

  Remain semi-solid at body temp = good storage for mammals

  General formula = CnH2nO2
• Unsaturated Fatty Acid 


  Fatty acid has 1 or more double bonds between carbon atoms

  Double bonds create kink in the chain

  Can't align uniformly > more double bonds = less straight and more fluid

  Lipid won't solidify readily - liquid at room temp
• Ester bond 


  Bond formed between glycerol + fatty acid in condensation reaction
• Phospholipid 


  Lipid made of a phosphate group, glycerol molecule with 2 fatty acids
• Bilayer 


  Double-layered structure forms from phospholipids > forms membranes

  Hydrophilic head points outwards?/hydrophobic fatty acid tail face inwards
• Emulsion Test 


  Test using ethanol, shaking then water identifies presence of a lipid = a milky white emulsion forms
• Lipids


  Contain carbon/hydrogen/oxygen

  individual molecules(Glycerol/fatty acids/phosphate group) NOT polymers (no monomers)

  Large/varied group of non-polar molecules/ insoluble in water but dissolve in organic solvents (alcohol/acetone)

  Form cell membrane/source of energy (2x energy per gram stored compared to carb)/ provide waterproof layer/ insulation and protection around organs

  Fats- solid at room temp

  oils - liquid at room temp
• Formation of Triglycerides 


  1 glycerol + 3 fatty acids > Glycerol has 3 hydroxyl groups(-OH) each combines with fatty acid

  Condensation reaction so produces 3 water molecules

  -OH group and -COOH bond are strong covalent bonds (ester)
• Function of Triglycerides 


  3 main roles - energy storage/ insulation/ protection

  • High ratio of energy storing carbon-hydrogen bonds to carbon atoms(have lots of chemical energy) > energy storage
  • low mass to energy ratio > good storage molecules, lots of energy in small volume
  • Large/ non-polar/ insoluble in water > no osmotic effect + don't affect water potential + clump together in insoluble droplets (hydrophobic inwards)
• Structure of Fatty Acids


  Organic compounds > general formula CH3(CH2)nCOOH, n rages from 2-28 and always an even number

  General formula written as RCOOH

  Made from carboxylic group (-COOH) + long chain hydrocarbon

  Hydrophobic with same basic structure but varying length / saturated or unsaturated

  Saturated with hydrogen > saturated fats H atoms attach to carbon skeleton
• Formation of Phospholipids

  
  

  Specialised lipids(similar to triglycerides) one fatty acid is substituted for a phosphate group

  Have hydrophilic head(contains glycerol and phosphate) and 2 hydrophobic fatty acid tail

  un/saturated but insoluble in water due to non-polar fatty acids

  Bilayer > multiple phospholipids
• Function of Phospholipids 


  Role to form cell membranes

  • Hydrophilic head and hydrophobic tail > form a bilayer with heads facing out to water on either side
  • Centre of cell membrane bilayer is hydrophobic > water-soluble substances can't pass through (barrier)
• Monomer 


  A single unit of polymer
• Polymer


  Many repeating monomers bonded together

  Broken into monomers by hydrolysis
• Monosaccharide


  Simple sugar monomers of carbohydrates (glucose/fructose)

  made into polymers by condesnation
• Disaccharide 


  Two monosaccharides joined by glycosidic bond (maltose/sucrose)
• Polysaccharide


  Polymer of many monosaccharides joined by glycosidic bond (cellulose, starch and glycogen)

  formed through condensation reactions

  long molecules so insoluble and suitable for storage

  broken into mono/disaccharides from hydrolysis to be used by organism/cell