carbohydrates

• examples of monosaccharides -

  glucose, galactose, fructose
• maltose -

  made up of two molecules of a glucose
• sucrose -

  formed of a glucose and fructose
• lactose -

  formed of a glucose and galactose
• what are the two isomers of glucose?

  a glucose and b glucose
• examples of polysaccharides -

  glycogen, starch, cellulose
• glycogen and starch made of -

  a glucose
• cellulose made of -

  b glucose
• cellulose -

  long, unbranched

  form microfibrils

  important in supporting the cell wall
• starch -

  made of amylose = unbranched, 1 -4 bonds, coiled and compact to store lots of energy

  made of amylopectin = branched, 1-4 and 1-6 bonds, side branches

  insoluble, compact, when hydrolysed a glucose transported easily
• bond between two monosaccharides -

  glycosidic bond
• glycogen -

  1-4 and 1-6 bonds

  lots of side branches to quickly release energy

  large and compact

  insoluble
• test for reducing sugars -

  using benedicts reagent

  1. add 2cm of food sample (liquid)
  2. add 2cm of reagent
  3. heat in a water bath for 5 minutes
  4. if turns brick red from blue, reducing sugar present
• test for non reducing sugar -

  1. add 2cm sample to 2cm hydrochloric acid
  2. put in a water bath for 5 minutes
  3. add sodium hydrogencarbonate to neutralise
  4. add 2cm reagent and put in water bath
  5. blue to brick red means non reducing sugar present