Biological Molecules

• what direction is the hydroxyl group in beta glucose?

  upwards
• what direction is the hydroxyl group in alpha glucose?

  downwards
• what is a monosaccharides?

  monomers from which larger carbohydrates are made
• what are the three monomers?

  glucose, galactose and fructose
• what is a disaccharide?


  a molecule formed by the condensation reaction of two monosaccharides and joined by glycosidic bonds
• which monosaccharides make maltose?

  glucose and glucose
• which monosaccharides make sucrose?

  glucose and fructose
• which monosaccharides make lactose?

  glucose and galactose
• what is a polysaccharide?

  a molecule formed by the condensation reaction of many monosaccharides and joined by glycosidic bonds
• what is it called when you join monomers and make water?

  condensation reaction
• what is it called when you break down a molecule into monomers using water?

  hydrolysis
• what is a glycosidic bond?

  o
• which carbohydrates are reducing sugars?

  all monosaccharides and some disaccharides
• what is a reducing sugar?


  a sugar that donates electrons
• what is the food test for a reducing sugar?

  Benedict's test
• what is Benedict's reagent?

  copper 2 sulfate
• what colour is a cu2+ ion?

  blue
• what colour is a cu+ ion

  red
• which isomer of glucose is starch made from?

  alpha
• where is starch found and what does it do used?

  it is a storage molecule in plants
• why is the fact that starch is insoluble better it at its function?

  because it doesn't affect the water potential of the cell
• why is starch compact?

  due to its 1,4 glycosidic bonds which mean it is twisted and coiled
• why is the fact that starch is compact better it at its function?

  large quantities can be stored in a small space
• why is the fact that starch is large better it at its function?

  it can't move across cell membranes?
• what are the two types of starch?

  amylose and amylopectin
• what gives amylopectin its branched structure?

  it has 1,6 glycosidic bonds as well as 1,4
• why do the branches make amylopectin better at its function?

  it can be more readily hydrolysed
• what does glycogen do?


  storage molecules in animals
• where is glycogen found?

  in liver and muscle cells
• which isomer of glucose is glycogen formed from?

  alpha
• what kind of glycosidic bonds does glycogen have?

  1,4 and 1,6
• what isomer of glucose is cellulose formed from?

  beta
• what is cellulose used for?

  cell walls
• what holds the chains together in cellulose?

  lots of hydrogen bonds between the chains forming groups of molecules called microfibrils
• what gives cellulose its strong structure?

  hydrogen bonds
• why is cellulose difficult to digest?

  organisms lack to enzymes to break the B4 linkages
• which type of starch has a helix shape?

  amylose
• which type of starch has branches?

  amylopectin
• what must you do to a non-reducing sugar to get a positive Benedict's test?


  boil then add hydrochloric acid leave then cool down. then neutralise by adding small amounts of sodium carbonate till it stops fizzing and check ph is neutral
• what elements does a lipid contain?

  carbon, hydrogen and oxygen