Carbs

• What elements make up carbohydrates?

  Carbon, Hydrogen, Oxygen (CHO)
• three structures of carbohydrates:

  monosaccharides, disaccharides, polysaccharides
• Monosaccharides of carbohydrates

  glucose, fructose, galactose
• Disaccharides of carbohydrates

  sucrose, maltose, lactose
• Polysaccharides of carbohydrates

  glycogen, starch, cellulose
• two common isomers of glucose

  alpha glucose, beta glucose
• Structure of alpha glucose

  OH on bottom

  
• Structure of beta glucose

  OH on top

  
• glycosidic bond


  covalent bond between two monosaccharides
• Hexose


  six carbon sugar (glucose)
• Pentose


  five carbon sugar (DNA and RNA)
• Maltose


  glucose and glucose joined by alpha 1-4 glycosidic bond
• Sucrose


  glucose and fructose joined by alpha 1-4 glycosidic bond
• Lactose


  glucose and galactose joined by beta 1-4 glycosidic bond
• Starch


  plant glucose storage polysaccharide, insoluble so does not affect water potential and is made up of amylose and amylopectin.
• Amylose


  polysaccharide - long, unbranched chain of 1-4 alpha glucose molecules. chains coil (helical) for compactness. iodine can become trapped in the coils causing colour change to blue/black. contains hydrogen bonds within the coil.
• Amylopectin


  polysaccharide - 1-4 alpha glucose, some 1-6 branched structure. As it has more ends it can be broken down quicker by enzymes. its structure is still coiled but the branches allow it to be more compact. contains hydrogen bonds.
• Glycogen structure


  branched polysaccharide, located in muscles and liver- similar to amylopectin, contains 1-6 glycosidic bonds.
• Glycogen function


  storage form of glucose in animals, less dense and broken down faster than starch due to high metabolic requirements of animals (energy needed for movement, respiration etc).
• Cellulose structure

  Long straight chains of B-glucose joined by 1-4 glycosidic bonds. Every other B-glucose monomer rotates 180. Glucose chains form microfibrils that layer to form a network. hydrogen bonds hold cellulose molecules to make microfibrils and these are held by more hydrogen bonds forming macrofibrils.
• Reducing sugar test

  Heat solution with Benedict's reagent in a water bath to test for reducing sugars. If it goes brick red then a reducing sugar is present.
• Non-reducing sugar test

  Following a negative reducing sugars test. Heat the solution with HCl to hydrolyse the non-reducing sugar into it's monosaccharides. Then perform the Benedict's test again. If you get a positive result (brick-red colour) after hydrolysis then a non-reducing sugar is present.
• Example of a reducing sugar


  glucose, maltose, and lactose
• Example of a non-reducing sugar

  sucrose