Carbohydrates

• Carbohydrates


  Hydrate of carbon; hydrate meaning water
• Carbohydrate formula


  CnH2nOn —> Cn(H2O)n (molecules of H2O are seen within structure)

  
• Carbohydrates


  • Have compounds that have the following functional groups: Polyhydroxy aldehydes, Polyhydroxy ketones

  
• Polyhydroxy


  Multiple hydroxyl groups bonded (-OH)

  
• Functional group


  Part of the structure that reacts
• Compounds that can be hydrolyzed


  Compounds that are "broken down" or hydrolyzed and seen with simpler compounds like polyhydroxy aldehydes or polyhydroxy ketones

  
• Saccharide


  Most basic unit that comprises the carbohydrate (polyhydroxy aldehyde or polyhydroxy ketone)

  
• Carbohydrate units


  • Monosaccharides
  • Oligosaccharides (few)
  • Polysaccharides (many)

  
• Sugar


  General designation for either a monosaccharide or a disaccharide (e.g. glucose, fructose, lactose)
• Monosaccharides


  • White, crystalline solid, all are sweet tasting, polar compounds with high melting points, water soluble, insoluble in organic solvents like diethyl ether
• Monosaccharide classification by functional group

  • Aldoses (contain an aldehyde group)
  • Ketoses (contain a ketone group)

  
• Aldose


  Contains an aldehyde group
• Ketose


  Contains a ketone group
• Aldehyde


  Carbonyl group is at the terminal end
• Ketone


  Carbonyl group is within the chain

  
• Monosaccharide classification by number of carbon atoms

  • Trioses (3 carbons)
  • Tetroses (4 carbons)
  • Pentoses (5 carbons)
  • Hexoses (6 carbons)
  • Heptoses (7 carbons)

  
• The most numerous carbon atoms formed in a carbohydrate is 7, but in the metabolic pathway the shortest is 3 (triose) and the longest is 7 (heptose)

  
• Heptose


  Longest but abnormal/very rare (e.g. heptulose)
• Hexose


  Longest and stable (e.g. glucose, fructose, galactose, mannose)
• CH2OH


  Condensed form of the last unit of a carbohydrate
• Chirality


  Concept that a molecule has four different entities attached, which can either be individual atoms or groups of atoms
• Chiral molecule


  A molecule whose mirror images are not superimposable
• Enantiomers


  Forms of carbohydrates that are mirror images of each other but cannot be superimposed
• Glyceraldehyde has two possible enantiomers, D-glyceraldehyde is the common, naturally occurring one

  
• Fischer projection


  Representation of carbohydrate structure in an open-chain form

  
• Drawing a Fischer projection

  1. Draw a vertical line

  2. Copy the first group of carbon (CHO or just H double bond O)

  3. In Fischer projection, do not draw the second group of carbon since it is an intersection, just copy the remaining H and OH

  4. Copy the rest (CH2OH)
• Numbering in Fischer projection

  The most oxidized end of the molecule has the lowest number
• D and L monosaccharides


  Differentiated by the position of the hydroxyl group on the chiral carbon (Carbon 2)

  
• Glucose and all other naturally occurring sugars are D-sugars, while amino acids are primarily of the L-form
• Enantiomers


  Mirror images of each other that cannot be superimposed
• 1. aldoses (Fischer projection)


  Generated by adding one carbon at a time, with the location of Carbon 2 being consistent

  
• 1. ketoses (Fischer projection)


  Very conservative clan, generated by adding one carbon at a time, with the location of Carbon 3 being consistent

  
• Haworth projection


  Used to represent carbohydrates in a ring or cyclic form

  
• Isomers


  Molecules with the same molecular formula but different structures
• Stereoisomers


  Isomers that differ in the three-dimensional arrangement of atoms in space
• Enantiomers


  Stereoisomers that are mirror images of each other and cannot be superimposed
• Diastereomers


  Stereoisomers that are not mirror images of each other
• sa


  mirror, hydroxyl din =

  
• correspondence


  Kung gano kalayo from the imaginary mirror, ganon din kalayo sa kabila (hydrogen based sa picture)
• Diastereomers


  • If there is no relationship or commonality between them
  • Not a reflection of each other
  • Stereoisomers whose molecules are not mirror images of each other
  • Correspondence is not observed, hence no mirror images