Carbohydrates are biological macromolecules composed of carbon, hydrogen, and oxygen. They serve several roles in living organisms including energy storage, structure, and development. Carbohydrates can be classified as monosaccharides, oligosaccharides, or polysaccharides depending on the number of sugar units. They function as long-term energy stores, structural elements of cells and tissues, and are involved in processes like fertilization and immune response. Common tests to detect carbohydrates include the Molish test which produces a purple color, and Fehling's test where a red precipitate forms.
2. A carbohydrate is a large biological molecule, or macromolecule,
consisting of carbon (C), hydrogen (H), and oxygen (O) atoms, usually
with a hydrogen:oxygen atom ratio of 2:1 (as in water).
They are called carbohydrates because the carbon, oxygen and
hydrogen they contain are generally in proportion to form water with the
general formula Cn (H2O)n.
3. Carbohydrate functions
• Carbohydrates have several roles in living organisms,
including energy transportation, as well as being
structural components of plants and arthropods.
• Carbohydrate derivates are actively involved in
fertilization, immune systems, the development of
disease, blood clotting and development.
• carbohydrates can function as long term food storage
molecules, as protective membranes for organisms and
cells, and as the main structural support for plants and
constituents of many cells and their contents.
15. Extraction of Monosaccharide
Fresh Plant Material
Homogenized with 4 vol. of distilled water for 15 min
Filtration – Filtrate is allow to concentrate in volume
to 1/10th
of its vol.
Allow to crystallize in the refrigerator
16. Extraction of high mol. Weight Carbohydrates
Plant Material is extracted with ethanol (which remove low mol wt
constituents),
Filter, collect the residue & extract with acetone followed by ether:
benzene(1:1) to remove lipids
Filtrate contain lipids, residue is extracted with 1 % NaCl
Filter (Filtrate contain natural water soluble polysaccharides)
Residue is extracted with 0.5 % ammonium oxalate sol.
Filtrate on acidification Residue extract with NaCl than with
ppt Pectin NaoH at room temp. for 24hr
Filtrate on acidification Residue is wash & dry,
gives Hemicellulose Pure Cellulose
17. Detection of Carbohydrates
• a) Molish test- 2-3 ml of aqueous extract solution was
treated with few drops of α-naphthol and conc. H2SO4
from sides of the test tube. Violet color ring was obtained
at the junction of two liquids shows positive test.
• b) Fehling’s test- Equal volume of Fehling’s solution A &
Fehling’s solution B was boiled for 1min. then equal
volume of extract solution was added & heated for 5-10
min. first yellow then brick red colored precipitate shows
the positive test.