You are What you Eat!

Identification of Macromolecules with Indicators

CarbohydratesContain aldehyde/ketone and alcohol

groupsCertain mono and disaccharides can be

detected due to their aldehyde groupsSome polysaccharides can be detected

because of their 3-D structureWater, soluble, hydrophilicCan’t be detected by hydroxyl groups2 tests: Benedict’s and Iodine

Benedict’sBenedict’s reagent + R-C=O Benedict’s (reduced)

+ R-C=O (oxidized) H

OH

Sugar gains an oxygen during reaction (oxidized); only reacts on free aldehyde group. Why not ketone?

Color change blue to burnt orange

Safety Note: must heat reaction for 2 minutes

IodineTests for starches (polysaccharide)Polymer of glucose in which chains are

coiled up in a particular way that they react with the Iodine molecules

Color change: Gold-Brown to a Blue-Black

FatsHydrophobic molecule consisting of a

glycerol molecule joined to 3 fatty acids.Important functional groups are hydroxyl

and carboxyl grpsLong hydrocarbon chains = nonpolarTests: Sudan III, Brown Bag or Solubility

Sudan IIIDepends on the detection of the

hydrocarbon groups in the 3 fatty acid tails.

The colored dye, Sudan III (red), and the hydrocarbon groups are both non-polar and stick together in their polar surroundings hydrophobic test (layer or reccish orange on top of water)

This also can be considered a “solubility test” as fats do not mix with the water layer

Brown BagFats leave a “greasy” mark on the cellulose

paper bagIf Sudan III is used in conjunction, the spots

show up a salmon-orange color

ProteinsPolymers of amino acidsCarboxyl and amino functional groupsThe covalent bond between amino acids is

called a “Peptide bond”Test: Biuret Test

Biuret TestBound amino groups (N-H2) reacts with

BiuretInteraction between copper (II) cations in

the Biuret reagent and the N-H in the peptide bonds

Color change= Aqua LavendarSafety Note: Biuret is highly basic! Be

careful!

Nucleic Acids (DNA and RNA)Are they in our foods?How can we test?

Why is this lab Important?What types of information can we get from

indicator tests?How does it relate to society? To health? To medicine?