Carbohydrates

• more than half of all organic carbon atoms are found in the carbohydrate materials of plants
• uses for carbohydrates of the plant kingdom extend beyond food
• cotton and linen used for clothing
• wood used for shelter, heating, and paper
• Carbohydrates are composed of C, H, O
• function of carbohydrates: energy, energy storage, raw materials, structural
• examples of carbohydrates: sugars, starches, cellulose
• Most of the matter in plants, except water, is carbohydrate material
• Carbohydrates account for 75% of dry plant material and are produced by photosynthesis
• Cellulose - Structural element
• Starch or glycogen - Energy reservoir
• Photosynthesis is the Process in which plants produce carbohydrates using carbon dioxide, water, and solar energy
• Carbohydrate oxidation provides energy
• Carbohydrate storage, in the form of glycogen, provides a short-term energy reservoir
• Carbohydrates supply carbon atoms for the synthesis of other biochemical substances (proteins, lipids, and nucleic acids)
• Carbohydrates form part of the structural framework of DNA and RNA molecules
• Carbohydrates linked to lipids are structural components of cell membranes
• Carbohydrates linked to proteins function in a variety of cell–cell and cell–molecule recognition processes
• Carbohydrate: Polyhydroxy aldehyde, ketone, or a compound that produces such substances upon hydrolysis
• Monosaccharides Contain single polyhydroxy aldehyde or ketone unit
• Monosaccharides Cannot be broken down into simpler substances by hydrolysis reactions
• Monosaccharides Contain 3–7 C atoms
• Monosaccharides 5 and 6 carbon species are more common
• Pure monosaccharides - Water soluble white, crystalline solids
• Monosaccharides - Glucose and fructose
• Disaccharides Contain 2 monosaccharide units covalently bonded to each other
• Disaccharides are Crystalline and water soluble substances
• Common disaccharides - Table sugar (sucrose) and milk sugar (lactose)
• Upon hydrolysis disaccharides produce 2 monosaccharide units
• Oligosaccharides Contain three to ten monosaccharide units covalently bonded to each other
• Oligosaccharides are usually found associated with proteins and lipids in complex molecules (Serve structural and regulatory functions)
• Polysaccharides Contain many monosaccharide units covalently bonded
• Number of monosaccharide units varies from a few 100 units to 50,000 units in a polysaccharide
• Examples of polysaccharide:

  Cellulose - Paper, cotton, wood; Starch - Bread, pasta, potatoes, rice, corn, beans, and peas
• Chiral center: C atom attached to 4 different groups
• monosaccharides are right handed
• Amino acids are left handed
• Enantiomeric pairs have same solubility in achiral solvents like ethanol and have different solubility in chiral solvent like D-2-butanol
• Triose or glyceraldehyde - 3 carbon atoms
• Tetrose - 4 carbon atoms