Organic Molecules

1
Organic Molecules
2
Organic Molecules

• The four major classes found in cells include
• carbohydrates
• lipids
• proteins
• nucleic acids

3
Carbohydrates

• Monomers (building blocks) are monosaccharides
• Polymers are formed by dehydration synthesis
• Polysaccharides many glucose molecules
  covalently bonded together
• starch plant storage carbohydrate

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Iodine Test for Starch

• In the presence of starch, iodine turns a dark
  purple, blue, or black color.
• The regular form of the glucose chains in starch
  traps the iodine molecules.
• Producing the dark color

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Lipids

• Soluble in organic solvents and insoluble in
  water
• Monomers (building blocks) triglycerides
  (glycerol 3 fatty acids)

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Test for Lipids

• Lipid based liquids leave stains (grease spots)
  behind when they dry and water based liquids do
  not.
• This can be used as a test

• Sudan IV is a lipid-soluble dye
• In the presence of lipids, the solution turns
  red/pink

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Protein

• Monomers amino acids
• Polymers are formed by dehydration synthesis
  between the amino group of one amino acid and the
  carboxyl group of a 2nd amino acid
• Bond formed a peptide bond

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Biuret test for Protein

• In the presence of protein, Biuret reagent reacts
  with the peptide bonds
• A pink color indicates the presence of peptide
  bonds
• The color intensity is related to the number of
  peptides bonds.
• The depth of color represents the number of
  peptide bonds

• Pinkfew
• i.e. peptide
• Purplemore
• Dark Purplevery many
• i.e. polypeptide