L9-10 carbohydrates

• functions of carbohydrates

  photosynthesis, respiration, structural role, recognition and in nucleic acids as the sugar
• carbohydrate formula

  (CH2O)n
• saccharides=carbohydrates

  i.e.monosaccharides, disaccharides, polysaccharides
• monosaccharides are the simplest carbohydrates containing

  • 1 aldehyde or ketone group
  • multiple hydroxyl groups
• monosaccharides contain _ carbon atoms

  3-7
• monosaccharides naming convention contain _ at the end

  -ose
• carbohydrates classified in 2 ways:

  1. aldehyde or ketone
  2. number of carbons in chain
• if carbohydrate has aldehyde group is called an

  aldose
• if carbohydrate contains a ketone group is called a 


  ketose
• number of carbons in carbohydrate defined as:

  3=triose

  4=tetrose

  5=pentose

  6=hexose

  7=heptose
• simplest monosaccharides have _ carbons

  3
• a molecule with n asymmetric centres (chiral carbons) and no plane of symmetry has _ isomers

  2^n
• most naturally occuring monosaccharides are in the _ form

  D
• aldehyde + alcohol makes


  hemiacetal
• ketone + alcohol makes


  hemiketal
• aldohexoses usually form _ rings

  pyranose
• anomeric carbon for aldoses is C1
• anomeric carbon for ketoses is C2
• optical rotation is defined as

  plane polarised light is rotated
• what is the equilibrium value of rotation changes

  +52.7 degrees
• pyranose rings adopt _ and _ conformations

  chair and boat
• furanose rings adopt _ conformations

  envelope
• example of carbohydrate

  glucose
• simplest member of aldose sugars is

  glyceraldehyde
• simplest member of ketose sugars is

  dihydroxyacetone
• in solution pentose and hexoses _ to form rings


  cyclise
• proportion of open chain form is less than _% in solution

  1
• what is an anomeric carbon?

  a chiral carbon formed from cyclisation
• pyranose is a 6 membered ring with _ carbon(s) and _ oxygen(s)

  5 and 1
• furanose is a 5 membered ring with _ carbon(s) and _ oxygen(s)


  4 and 1
• monosaccharides join through a _ reaction

  condensation reaction
• condensation reaction produces a _ molecule


  water
• monosaccharides bonded together form

  glycosidic bonds
• glycosidic bond is between

  anomeric carbon of one sugar and hydroxyl group of another
• reducing sugars contain

  free aldehyde or ketone
• to test for reducing sugar

  add copper ion, positive test produces red precipitate
• carbohydrates have direction because they have:

  reducing end and non-reducing end
• glycosyltransferases join sugars together in 


  glycosidic bonds
• polysaccharides =

  many sugars
• oligosaccharides=

  small number of sugars (3-10)