Carbohydrates

• Carbohydrates


  Polyhydroxy aldehydes or ketones or compounds which yield these on hydrolysis
• Functions of carbohydrates


  • Sources of energy
  • Intermediates in the biosynthesis of other basic biochemical entities (fats and proteins)
  • Associated with other entities such as glycosides, vitamins and antibiotics
  • Form structural tissues in plants and in microorganisms (cellulose, lignin, murein)
  • Participate in biological transport, cell-cell recognition, activation of growth factors, modulation of the immune system
• Glucose


  • Provides energy for the brain and 1/2 of energy for muscles and tissues
• Glycogen


  • Stored glucose
• Monosaccharides


  Carbohydrates that cannot be hydrolyzed to simpler carbohydrates
• Disaccharides


  Carbohydrates that can be hydrolyzed into two monosaccharide units
• Oligosaccharides


  Carbohydrates that can be hydrolyzed into a few monosaccharide units
• Polysaccharides


  Carbohydrates that are polymeric sugars
• Classification of carbohydrates


  • Monosaccharides
  • Disaccharides
  • Oligosaccharides
  • Polysaccharides
• Monosaccharides


  Simple sugars with multiple OH groups, based on number of carbons (3, 4, 5, 6) they are trioses, tetroses, pentoses or hexoses
• Disaccharides


  2 monosaccharides covalently linked
• Oligosaccharides


  A few monosaccharides covalently linked
• Polysaccharides


  Polymers consisting of chains of monosaccharide or disaccharide units
• Carbohydrates (glycans) have the basic composition of (CH2O)n, where n = 3, 5, 6
• Simple carbohydrates


  • Monosaccharides (single sugars)
  • Disaccharides (2 monosaccharides)
• Characteristics of carbohydrates


  • Consist of carbon, hydrogen, & oxygen
  • Energy containing molecules
  • Some provide structure
  • Basic building block is a monosaccharide
• Monosaccharides


  Also known as simple sugars, classified by number of carbons and whether aldoses or ketoses, most are straight chain compounds
• 1. glyceraldehyde is the simplest of the aldoses (aldotriose)
• All other sugars have the ending 'ose' (glucose, galactose, ribose, lactose, etc.)
• Glucose


  The chemical formula is C6H12O6, it is a six sided ring
• Relative sweetness of different sugars

  • Sucrose (100)
  • Glucose (74)
  • Fructose (174)
  • Lactose (16)
  • Invert Sugar (126)
  • Maltose (32)
  • Galactose (32)
• Aldoses


  Have an aldehyde group at one end
• Ketoses


  Have a keto group, usually at C2
• Stereoisomers


  Compounds having same structural formula, but differ in spatial configuration
• D vs L designation

  Based on the configuration about the single asymmetric C in glyceraldehyde
• Enantiomers


  Mirror image pairs of stereoisomers
• Epimers


  Stereoisomers that differ only in configuration about one chiral center
• Hemiacetal


  Formed when an aldehyde reacts with an alcohol
• Hemiketal


  Formed when a ketone reacts with an alcohol
• Anomers


  Stereoisomers formed when a ring is formed (α, β)
• Haworth projections


  Representations of the cyclic sugars
• Haworth-Projektionen


  Einfache Ringdarstellung in Perspektive
• Glucose kann entweder Furanose- oder Pyranosestrukturen bilden
• Monosaccharide


  • Glucose
  • Fructose
  • Galactose
• Zuckerderivate


  • Aminozucker (z.B. Glucosamin)
  • N-Acetylglucosamin
• Stärke ist das am häufigsten vorkommende Speicherkohlenhydrat in Pflanzen
• Formen von Stärke


  • Amylose
  • Amylopektin
• Cellulose ist der am häufigsten vorkommende Kohlenhydratstoff
• Aminozucker sind Bestandteile von Mukopolysacchariden