Hexose Monosaccharides:

  • Glucose
  • Fructose
  • Galactose

Pentose Monosaccharides:

  • Ribose
  • Deoxyribose
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Disaccharides and Polysaccharides


  • Sucrose
  • Lactose
  • Maltose


  • Cellulose
  • Starch
  • Glycogen
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Disaccharides and Polysaccharides


  • Sucrose
  • Lactose
  • Maltose


  • Cellulose
  • Starch 
  • Glycogen


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Making Disaccharides

Condensation is bond making and hydrolysis is bond breaking.

  • When a glycosidic bond is formed, a water molecule is also formed.

What are disaccharides made from?

  • Sucrose -------> Glucose + Fructose (broken down by sucrase)
  • Lactose --------> Glucose + Galactose (broken down by lactase)
  • Maltose -------> Alpha Glucose + Alpha Glucose
  • Cellobiose -------> Beta Glucose + Beta Glucose
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  • Made up of amino acids, of which there are 20.
  • Diagram of amino acids:
  • Cysteine makes disulphide bonds as it contains a sulphur.
  • Bond between amino acids = peptide bond
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R Groups and Polypeptides

R Groups:

  • Different sizes
  • Different atoms within each R Group
  • Can be polar (charged) or non-polar

If the structure isn't right, it is more difficult to carry out the function.

How are protein molecules structured?:

  • Shape is largely determined by R Group interaction, if the R Groups share the same charge, they will repel each other, if they are oppositely chagred they will attract each other.
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Protein Structure

  • Primary Structure: A linear chain of amino acids.
  • Secondary Structure: Chain becomes either alpha helix (maintained by hydrogen bonds) or a beta pleated sheet (maintained by hydrogen bonds)
  • Tertiary Structure: Vital the the function of the protein, eg a hormone must be able to fit into a hormone receptor and an enzyme must have an active site that is complementary to the substrate.
  • Quaternary Structure: When a number of polypeptide chains are fitted together, eg haemoglobin.
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Biochemical Tests

Starch: Add iodine solution, if starch is present, it will become black.

Reducing Sugars: Perform the Benedict's test, add Benedict's solution and heat until water boils, this should produce a brick red precipitate.

Non-Reducing Sugars: Add a small amount of acid and then bring to the boil in a water bath, then allow to cool and add alkali to neutralise, add benedict's solution and heat again in a water bath, the resulting precipitate should be brick-red if positive.

Lipids: Add ethanol to substance subject to testing and add this into water column, if results are positive, the water will become cloudy/milky. (This is the emulsion test)

Proteins: Add drops of Biuret Solution to the sample, stirring gently at the same time, if results are positive it will turn purple/violet.

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