Revision!

1
Revision!

• L.O to summarise biochemical tests
• to apply knowledge to questions

2
Biochemical Tests are used to indicate the
presence / absence of biological molecules

• http//www.bbc.co.uk/schools/gcsebitesize/science/
  add_ocr/chemicals/biologicalcompoundsact.shtml

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Summary Table
Biological Molecule Biochemical test Positive Result




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Summary Table
Biological Molecule Biochemical test Positive Result
Protein
Lipid
Reducing Sugar
Non Reducing Sugar
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Summary Table
Biological Molecule Biochemical test Positive Result
Protein Biuret Purple
Lipid
Reducing Sugar
Non Reducing Sugar
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Summary Table
Biological Molecule Biochemical test Positive Result
Protein Biuret Purple
Lipid Emulsion Test (ethanol H2O) White precipitate
Reducing Sugar
Non Reducing Sugar
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Summary Table
Biological Molecule Biochemical test Positive Result
Protein Biuret Purple
Lipid Emulsion Test (ethanol H2O) White precipitate
Reducing Sugar Benedicts HEAT Brick red
Non Reducing Sugar
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Biological Molecule Biochemical test Positive Result
Protein Biuret Purple
Lipid Emulsion Test (ethanol H2O) White precipitate
Reducing Sugars (mono and most di) Benedicts HEAT Brick red
Non Reducing Sugar (sucrose) 1. Hydrolyse into monomers by HCL boiling. 2. Neutralise with alkali. 3. Retest with Benedicts HEAT Brick red
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Application of Knowledge

• http//www.classtools.net/education-games-php/time
  r

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Question 1

1. A Protein B Lipid C Reducing Sugar
2. Hydrolyse with acid and then neutralise with
   alkali, re test with Benedicts
3. Carbon, Hydrogen, Oxygen

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Question 1 (again!)

• 1 a) C12H22O11 (Because H2O is formed in the
  condensation reaction)
• 1 bi) Purple
• 1 bii) Because its a protein
• 1 c) Benedicts AND heat
• Brick Red

12
Application of Knowledge

• http//www.classtools.net/education-games-php/time
  r

13
Question 1 (again!!)

• 1 a) Nitrogen
• 1 b i) Benedicts AND heat
• Brick Red
• 1 b ii ) Substance A (glucose)
• 1 c i) Forming bonds, with the removal of water
• 1 c ii) C (protein)
• 1 d i) Substance D
• 1 d ii) Maximum amount of hydrogen atoms
• NO double bonds / all carbons attached to two
  hydrogens