Carbphydrates

• Carbohydrates


  • Derived from the French word hydrate de carbone
  • General molecular formula CH₂O
  • Main source of energy
  • Structural components for many organisms
• The human body by mass is made up of 1% carbohydrates
• (45-65% of our food should come from carbohydrates)
• Types of carbohydrates


  • Simple carbohydrates
  • Complex carbohydrates
• Simple carbohydrates


  • Also called simple sugars
  • Quick energy sources
• Our body breaks down simple carbs easily, as a result blood sugar levels rise and the drop quickly
• They come from sugar and they do not usually supply any other nutrients
• All carbohydrates are made up of units of sugar (saccharide units)
• Categories of simple carbs

  • Monosaccharides
  • Disaccharides
• Most common monosaccharides


  • Glucose
  • Fructose
  • Galactose
  • Mannose
• Most common disaccharides


  • Sucrose
  • Lactose
  • Maltose
• Oligosaccharides


  • 3-10 monosaccharide units
  • Examples: raffinose (galactose glucose-fructose), kestose (glucose-fructose-fructose)
• Important polysaccharides


  • Cellulose
  • Starch
  • Glycogen
• Monosaccharides


  Classified according to functional group
• Aldoses


  • Glucose
  • Galactose
  • Mannose
  • Ribose
  • Xylose
  • Arabinose
• Ketoses


  • Fructose
  • Ribulose
• Aldose


  • CH=O
• Ketose


  • Both up & down CH2OH
• Monosaccharides classified by number of carbon atoms

  • Trioses (3)
  • Tetroses (4)
  • Pentoses (5)
  • Hexoses (6)
• All monosaccharides are reducing sugars because all monosaccharides have an aldehyde group (if they are aldoses) or can tautomerize in solution to form an aldehyde group (if they are ketoses)
• Glyceraldehyde


  Simplest aldose monosaccharide and simplest carbohydrate
• Glyceraldehyde exists as two enantiomers
• All natural occurring sugars are D-sugars
• 1. glucose


  • Blood sugar is the basic source of energy for all living things
  • Referred as "grape sugar"
  • The most stable form of glucose is β-D-glucose
• 1. galactose


  A sugar in milk and yogurt
• 1. mannose


  Bitter sugar
• 1. fructose


  MONOSACCHARIDE-KETOHEXOSES (6), Sugar found in fruit, honey and vegetables, Sweetest sugar
• Disaccharide


  Two monosaccharides can be linked together to from a "double" sugar or disaccharide
• Glycosidic bond or glycosidic linkage


  The resulting bond between sugar units or saccharide units
• Reducing sugar


  A disaccharide can be a reducing sugar or a non-reducing sugar
• Maltose


  • Grain starch broken down into sugar, Glucose + glucose, Can be hydrolyzed by maltase and thus can be fermented by yeast
• Lactose


  Milk sugar, Glucose galactose, Reducing sugar, In the body, it is broken down by lactase and by emulsin
• Sucrose


  Table sugar is made from sugar beets or sugar cane, Glucose + fructose, Non-reducing sugar
• Complex carbohydrates


  • Supplies longer lasting energy, as well as nutrients and fiber that the body needs, They are made up sugars molecules that are strung together in long, complex chain, All polysaccharides are non-reducing
• Trisaccharide


  3 glycose units - raffinose (D-galactose + D-glucose + D-fructose)
• Tetrasaccharide


  4 glycose units - stachyose (raffinose + D-glucose)
• Pentasaccharide


  5 glycose units - verbascose (raffinose + two D-glucose)
• Starch


  • The principal polysaccharide used by plants to store glucose for later use as energy, Stored often in seeds, Common sources are: rice, beans, wheat, corn, potatoes, Insoluble in water
• Amylose


  Consists of linear, unbranched chains of several hundred glucose residues (units), Linked by a glycosidic bond between their a-1,4 carbon atoms
• Amylopectin


  Being highly branched, The total number of glucose residues in a molecule of amylopectin is several thousand, At approximately every thirtieth residue along the chain, a short side chain is attached by a glycosidic bond to the No carbon atom (branched: a-1,6 C; linear: a-1,4 C)