Biological Molecules

• polymer


  long molecules formed from combinations of many monomers joined together
• condensation reaction


  a chemical reaction in which two or more molecules join and produces one water molecule
• hydrolysis reaction


  A chemical reaction that breaks apart a larger molecule by adding a molecule of water
• isomers


  Compounds with the same chemical formulae but different structures.
• carbohydrates


  compounds made from carbon, hydrogen and oxygen (monosaccharides, disaccharides and polysaccharides), important energy store
• monosaccharide


  simple sugars (glucose, fructose, galactose)
• disaccharide


  two monosaccharides joined together by a glycosidic bond
• polysaccharide


  many sugar units joined by a glycosidic bond
• maltose


  α glucose + α glucose

  
• lactose


  glucose + galactose

  
• sucrose


  glucose + fructose

  
• where is lactose found?

  milk
• where is maltose found?

  germinating seeds
• where is sucrose found?

  table sugar
• cellulose


  polymer of β glucose

  
• starch


  polymer of α glucose (amylose + amylopectin)

  
• what is the structure of cellulose?


  long, unbranched chains of β glucose, insoluble
• where is cellulose found?

  plant cell walls
• why is cellulose strong?

  chains linked by h bonds form microfibrils giving high tensile strength to prevent osmotic lysis
• what is the structure of starch?


  long, highly-branched, compact helix and insluble
• where is starch found?

  energy stores in plants
• glycogen


  storage form of glucose in animals, compact, highly-branched structure

  
• limits of the Benedict's test


  isn't specific or sensitive
• what is the test for reducing sugars?

  Benedict's test
• what colour will the solution be in the presence of reducing sugars?

  green → red (nearer red, higher conc reducing sugar)
• what is the test for starch?

  iodine test
• if starch is present, what colour will the iodine be?

  orange → blue-black
• covalent bond


  a chemical bond in which two atoms share a pair of electrons

  
• ionic bond


  the bond between two oppositely charged ions

  
• hydrogen bond


  the attraction between a partially positive hydrogen atom(δ+) and a partially negative atom(δ-)

  
• lipid


  compounds mostly made from carbon and hydrogen (triglycerides and phospholipids), energy store, thermal insulator, for buoyancy and protection
• triglyceride


  1 glycerol + 3 fatty acid tails joined by an ester bond

  
• glycerol


  a three-carbon alcohol with a hydroxyl group(-OH) attached to each
• fatty acid


  a carboxylic acid made of a hydrocarbon chain + a terminal carboxyl group
• saturated fatty acid


  no double bonds between carbon atoms, maximising the number of hydrogen atoms that can attach to the carbon skeleton.

  
• unsaturated fatty acid


  a fatty acid with one or more double bonds between the carbons (mono or poly)

  
• phospholipid


  1 glycerol + 2 fatty acids + 1 phosphate

  
• polar


  molecule with partial charges due to a difference in electronegativity
• hydrophobic


  water repulsion
• hydrophillic


  attracted to water