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• Carbohydrates consist of

  • Polyhydroxyaldehydes
  • Polyhydroxyketones
  • Derivatives
• Carbohydrates


  • They are the most abundant constituents of plants and animals
  • They have vital functions including storing chemical energy, providing structural support, and being essential components of genetic material and cellular communication
• Classes of carbohydrates

  • Monosaccharides
  • Disaccharides
  • Oligosaccharides
  • Polysaccharides
• Monosaccharides


  Cannot be hydrolyzed to simpler components, general formula CnH2On where n varies from 3 to 8, classified according to functional groups present
• Types of monosaccharides

  • Aldoses (contain aldehyde group, e.g. glucose, galactose, ribose)
  • Ketoses (contain ketone group, e.g. fructose, ribulose)
• 1. and L-

  Designations for the configuration of the -OH group on the penultimate carbon of monosaccharides
• Naturally occurring monosaccharides are D-sugars
• Relationship between D-ketoses

  Shown in diagram
• Relationship between D-aldoses

  Shown in diagram
• Disaccharides


  Consist of two monosaccharide units joined by a glycosidic bond
• Examples of disaccharides

  • Sucrose
  • Lactose
  • Maltose
• Non-reducing disaccharides

  Have an ether linkage between the monosaccharides, e.g. sucrose
• Reducing disaccharides

  Have a free hemiacetal group, e.g. lactose, maltose
• Polysaccharides


  Consist of many monosaccharide units, can be homopolysaccharides or heteropolysaccharides
• Examples of polysaccharides

  • Cellulose
  • Starch
  • Glycogen
• Cellulose


  A homopolymer of glucose linked by β-1,4 glycosidic bonds
• Starch

  Consists of two types of glucose homopolymers: amylose (linear, α-1,4 bonds) and amylopectin (branched, α-1,4 and α-1,6 bonds)
• Glycogen


  A branched homopolymer of glucose, similar to amylopectin but with a higher degree of branching
• Other biologically and commercially important polysaccharides

  • Chitin
  • Hyaluronic acid
  • Carrageenan
• Chitin


  Repeating units of N-acetyl-D-glucosamine bound by β-1,4 glycosidic linkages, provides structural support
• Hyaluronic acid


  Has a dimeric repeating unit of D-glucuronic acid and N-acetylglucosamine, functions as a lubricant and shock absorber
• Carrageenan


  Sulfated polysaccharides consisting of D-galactopyranose polymers with alternating β-1,4 and α-1,3 glycosidic linkages, used as a food additive
• Thermodynamically unfavorable reaction


  Can be driven by a highly favorable reaction that is coupled to it
• ATP

  The universal currency of free energy in biological systems, consists of adenine, ribose and a triphosphate
• Hydrolysis of ATP


  Releases a large amount of free energy, forming ADP+Pi or AMP+PPi
• ATP cycle

  ATP is continuously formed and consumed for processes like motion, active transport, biosynthesis, and signal amplification
• NADH.H* and FADH2


  Major electron carriers in the oxidation of fuel molecules
• Three stages of catabolism

  Large biomolecules (fats, polysaccharides, proteins) broken down into building block molecules (fatty acids, glucose, amino acids)

  2. Building block molecules converted to common degradation product (pyruvate, acetyl CoA)

  3. Common degradation product fully oxidized via TCA cycle and oxidative phosphorylation to produce CO2, H2O, and ATP
• Glycolysis

  Breakdown of glucose to pyruvate, producing ATP
• ATP

  Adenosine triphosphate
• ADP

  Adenosine diphosphate
• Pi

  Orthophosphate
• AMP

  Adenosine monophosphate
• PPi

  Pyrophosphate
• ATP hydrolysis

  1. ATP + H₂O = ADP + Pi

  2. ATP + H₂O = AMP + PPi
• AG=-7.3 kcal/mol
• ATP is continuously formed and consumed
• Processes ATP is used for

  • Motion
  • Active transport
  • Biosynthesis
  • Signal amplification
• The ATP-ADP cycle is the fundamental mode of energy exchange in biological systems
• NADH.H*


  Major electron carrier in oxidation of fuel molecules