3.1.2 Monomers and Polymers

Monosaccharides

Sugars can be classified as @@reducing or non-reducing;@@ this classification is dependent on their ability to @@donate electrons@@

Examples of Polymers can be amino acids, nucleotides, and monosaccharides

A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule

Reducing Sugars

  • Sugars can be classified as reducing or non-reducing; this classification is dependent on their ability to donate electrons
  • Reducing sugars @@can donate electrons@@ (the carbonyl group becomes oxidised), the sugars become the @@reducing agent@@
  • Thus reducing sugars can be detected using @@Benedict’s test@@ as they reduce the soluble copper sulphate to insoluble brick-red copper oxide

Non-Reducing Sugars

  • Non-reducing sugars @@cannot donate electrons@@, therefore they cannot be oxidised
  • To be detected non-reducing sugars must first b@@e hydrolysed to break the disaccharide@@ into its two monosaccharides before a Benedict’s test can be carried out

This is done by adding @@dilute hydrochloric acid, then neutralising@@. The acid will break down the non-reducing sugars into monosaccharides. After adding acid, neutralise the solution with @@sodium hydrogencarbonate@@

Using chromatography to separate a mixture of Monosaccharides

  • Mixtures containing coloured molecules, such as ink or chlorophyll, do not have to be stained as they are already coloured. Mixtures of colourless molecules, such as a mixture of monosaccharides, have to be stained first
  • A spot of the @@stained monosaccharide sample mixture is placed on a line@@ at the bottom of the chromatography paper
  • Spots of @@known standard solutions@@ of different monosaccharides are then placed on the line beside the sample spot
  • The chromatography paper is then @@suspended in a solvent@@
  • As the solvent travels up through the chromatography paper, the @@different monosaccharides within the mixture separate out at different distances from the line@@
  • The unknown monosaccharides can then be identified by @@comparing and matching them with the chromatograms of the known standard solutions@@ of different monosaccharides
  • If a spot from the monosaccharide sample mixture is at the same distance from the line as a spot from one of the known standard solutions, then the mixture must contain this monosaccharide