BIOCHEM - LAS 1: CARBOHYDRATES

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Saccharides

unit structure of carbohydrates

Carbohydrates

provide body with stored energy, function as structural components

Monosaccharide

White crystalline, Soluble, Sweet

Disaccharide

White crystalline, Soluble, Sweet

Starch

Amorphous powder, slightly soluble, tasteless

Cellulose

Fibrous, Insoluble, Tasteless

Glycogen

Principal storage form of carbohydrates in the mammalian body

Glycogen

Supply is necessary especially for nervous system and erythrocytes

Glycogen

good source of energy for sudden, strenuous activity

Hypoglycemia

decrease in glucose level below 70 mg/dL which causes brain dysfunction, coma, and death

Liver glycogen extraction

involves breaking down animal tissues and separating glycogen from other cellular components using solvents

Plant starch extraction

involves mechanical grinding of plant tissues, washing, and sedimentation to isolate starch granules

Molisch test

concentrated H2SO4 (dehydrating agent) catalyzes the dehydration of sugars to form furfurals (from pentoses)/hydroxymethyl furfurals (from hexoses); these furfurals then condense with sulfonated alpha-naphthol to give a purple/violet-colored ring

Anthrone's test

the furfurals and hydroxy-methyl furfurals give condensation products with anthrone that are bluish-green in color

Iodine test

used to test for the presence of starch

Iodine test

Starch turns into an intense blue-black color upon the addition of aqueous solutions of the triiodide anion, due to the formation of an intermolecular charge-transfer complex.

Seliwanoff's test

used to distinguish aldoses and ketoses

Seliwanoff's test

dehydrated ketose reacts with 2 equivalents of resorcinol in a series of condensation reactions to produce a complex (not precipitate) termed XANTHENOID, with a deep red color. Aldoses may react slightly to produce a faint pink to cherry red color if the test is prolonged

5-hydroxymethyl furfural

yielded by ketoses dehydrated in the presence of concentrated acid

Bial Orcinol test

used to detect pentoses

Bial Orcinol test

reaction is due to the formation of furfural in the acid medium which condenses with orcinol in the presence of ferric ions to give a blue-green colored complex

Mucic Acid test

used to detect the presence of galactose and lactose

Mucic acid

galactaric acid, a dicarboxylic acid formed from galactose due to the oxidation of both aldehyde and primary alcoholic group at C1&C6

Mucic acid

the only saccharic acid which is insoluble in cold water

Reducing sugars

carbs that have free aldehyde/ketone groups capable of reducing other substances. They can donate electrons to other molecules in chemical reactions, thereby undergoing oxidation themselves.

Osazone test

used to detect reducing sugars

Fehling's test

used to detect reducing and non-reducing sugar; can be used to screen for glucose in urine, thus detecting diabetes

Rochelle salt

aqueous potassium sodium tartrate

Fehling's test

sugar which contains a free aldehyde or ketone groups reduces the alkaline solution of copper salts to cuprous oxide

Benedict's test

used to distinguish between reducing and non-reducing carbs

Barfoed's test

used to distinguish between a reducing mono- and disaccharide

Fehling's test

a qualitative test used to distinguish between reducing and non-reducing sugar (sucrose) based on their ability to reduce copper ions in the reagent solution, providing a qualitative assessment of their presence

Barfoed's test

useful for differentiating between monosaccharides (glucose, fructose, galactose) and certain disaccharides (maltose, sucrose, and lactose) based on their ability to react and form a colored precipitate in acidic conditions

Mucic acid test

chemical test used to detect galactose (or substances containing it, like lactose)

Mucic acid test

When galactose is oxidized with nitric acid, it produces mucic acid after nitric acid treatment, meaning galactose/lactose is present