Carbohydrates

• Carbohydrate: Compounds made from carbon, hydrogen and oxygen, Either monosaccharides, disaccharides or polysaccharides.
• In carbohydrates, the basic monomer unit is a sugat, or a saccharide.
• Monosaccharide: A single sugar (e.g. glucose).
• Organic Molecule: Molecules containing carbon, hydrogen and oxygen.
• Disaccharide: Made up of two sugar units that are formed by a condensation reaction. Monosaccharides are joined by a glycosidic bond.
• Polysaccharide: Made of many sugar units that are formed by a condensation reaction. Monosaccharides are joined by a glycosidic bond.
• Monosacchardies are sweet tasting, soluble substances.
• Monosaccharides have the general formula (CH2O)n. n is any number between 3 and 7.
• Examples of monosaccharides include: glucose, galactose and fuctose.
• Glucose is a hexose sugar (6-carbon).
• Glucose has the formula C6H1206.
• Hexose sugar: A sugar made up of 6 carbons.
• Glucose: C6H12O6 - A single sugar, which is used in respiration.
• Glucose has two isomers: alpha-glucose and beta-glucose.
• Reducing Sugar: A sugar that serves a a reducing agent. All monosaccharides are reducing sugars, along with disaccharides.
• Reducing Sugars Test: Heat solution with Benedict's reagent to test for reducing sugars. Goes brick red when a reducing sugar is present.
• Benedict's Reagent: Blue solution which is used to test for reducing and non-reducing sugars.
• Glycosidic Bond: Bond between sugar molecules in disaccharides and polysaccharides.
• Non-reducing Sugars: A sugar which can't serve as a reducing agent. For example, polysaccharides.
• Non-reducing Sugars Test: Following a negative reducing sugars test. Heat the solution with HCl to hydrolyse the non-reducing sugat into its monosaccharides. Then preform Benedict's test again. If you get a positive result (brick red) after hydrolysis then a non-reducing sugar is present.
• Glucose joined to glucose forms maltose (a disaccharide).
• Glucose joined to fructose forms sucrose (A disaccharide).
• Glucose joined to galactose forms lactose (a disaccharide).
• When monosaccharides join, a molecule of water is removed, therefore it is a condensation reaction. The bond formed is a glycosidic bond.
• When water is added to a disaccharide, it breaks the glycosidic bond releasing its consituent monosaccharides. This is called hydrolysis.
• Different types of glucose:

  A) Alpha-glucose

  B) Beta-glucose

  
• Benedict's Test:

  A) Add the test solution into a test tube.

  B) Add Benedict's solution.

  C) Heat in a water bath (boiling).

  D) Brick-red for positive result.

  
• Polysaccharides are polymers formed by combining together many monosaccharides.
• Polysaccharides are large, insoluble molecules.
• When hydrolysed, a polysaccharide breaks down into its monsaccharides and disaccharides.
• Polysaccharides are formed by a condensation reaction of monosaccharides.
• Polysaccharide, disaccharide, monosaccharide?

  A) monosaccharide

  B) disaccharide

  C) polysaccharide

  
• To test for starch, place the sample in a test tube. Add some drops of iodine solution and stir. If starch is present, the solution will turn blue-black from orange.