ACTIVITY 3 Flashcards
(14 cards)
Reducing sugars may be differentiated from each other by the osazones they form with _______.
Phenylhydrazine
are yellow crystalline compounds which have characteristic forms, definite time of formation, and different relative solubilities in hot water.
Osazones
Some of the monosaccharides give identical osazones which differ in their __________
rates of formation.
(For example, fructose forms an osazone faster than glucose even though the osazones formed are the same.)
how to identify reducing sugar using osazone
Microscopic examination and reference to standard osazones
is used to differentiate helical from non-helical or linear polysaccharides.
Iodine solution
Unbranched helical polysaccharides like amylose trap iodine molecules, producing the characteristic _______________.
deep blue-black complex.
Amylopectin which is branched and helical, gives a
_____________ with iodine
purple or red-violet color
while glycogen gives colors varying from
wine red to brown
The color differences are apparently related to the extent of coiling in the glycogen.
Cellulose, inulin, gum-arabic, and agar-agar have linear structures and thus, give ______ with iodine or the
color of iodine solution is retained.
no color
Similarly, monosaccharides and disaccharides do not form
_____ colors with iodine because ____________
dark colors;
they are too small to trap iodine molecules.
Starch - Iodine Test
Deep blue = unbranched helical
Dextrin iodine test
purple - branched helical
Glycogen Iodine Test
wine red to brown - branched helical
gum-arabic, agar-agar iodine test
no color - linear
