Qualitative Analysis of Carbohydrates Flashcards
skeletons of
covalently bonded carbon atoms
organic compounds
are the
major components of cells and tissues
organic compounds
They provide energy for life processes, participate and
regulate metabolic reactions, and transmit information
organic compounds
Organic molecules in living organisms
can be classified either
carbohydrates
proteins
lipids
nucleic acids
are compounds that contain carbon, hydrogen and oxygen.
carbohydrates
includes a variety of compounds such as sugars, starches and cellulose.
carbohydrates
serve as energy sources for cells, while cellulose are structural components of the walls that
surround plant cells
what compounds (2)
sugars
starches
carbohydrates that have one sugar molecule
monosaccharides
carbohydrates with two sugar molecules
dissacharides
carbohydrates with many sugar unts
polysaccharides
is a chemical test which is used to check for the presence of carbohydrates in a given analyte
Molisch’s test
a solution of α-naphthol in ethanol
Molisch’s reagent
involves the addition of a solution of α-naphthol in ethanol to the analyte and the subsequent addition of a few drops of concentrated H2SO4 to the mixture
Molisch’s test
Molisch’s test reagents (2)
H2SO4 (sulfuric acid)
α-naphthol in ethanol
The formation of a ___or a ____-red ___at the point of contact between the H2SO4 and the analyte + Molisch’s reagent mixture confirms the presence of carbohydrates in the analyte.
purple
purplish-red
A positive reaction for Molisch’s test is given by almost all carbohydrates but exceptions
tetrose
triose
some compounds aside from carbohydrates that give positive results for Molisch’s test
glycoproteins
nucleic acids
tend to undergo hydrolysis when exposed to strong mineral acids and form monosaccharides
glycoproteins
nucleic acids
In Molisch’s test, the carbohydrate (if present) undergoes dehydration upon the introduction of concentrated hydrochloric or sulphuric acid, resulting in the formation of an ____
aldehyde
undergoes condensation along with two phenol-type molecules (such as α-naphthol, resorcinol, and thymol), resulting in the formation of a purple or reddish-purple coloured complex.
What kind of compound formed in molisch’s test
aldehydes
study the molisch’s test principle
+1
Molisch’s teast procedure
- Add 2 drops of Molisch reagent (prepared by dissolving 0.1g of ∞napthol in 2 mL of
ethanol) to 2 mL of sugar solution (glucose, fructose, galactose, sucrose, maltose,
lactose, starch) and mix. - Incline the tube, and gently add 2 mL of concentrated sulfuric acid down the side of
the test tube. - A purple color at the interface between the sugar and acid indicates a positive result.
is a chemical test that can be used to check for the presence of reducing sugars
in a given sample
Benedict’s test
compounds that Benedict test can be used to dientify
free ketone/aldehyde