Disaccharide

What are disaccharides? How will you identify them in the laboratory? What is the normal level of glucose in the blood?
Answer:

Disaccharides:

Disaccharides are oligosaccharides containing two monosaccharide units held together by a glycosidic bond.

Properties:

“Understanding disaccharides through FAQs: Structure, types, and uses explained”

Types:

1. Reducing disaccharides

What is a disaccharide

2. Non-reducing disaccharides.

“Importance of studying disaccharides for biochemistry students: Questions explained”

Laboratory tests for disaccharides:

1. Molisch test:

It is a general test for the detection of carbohydrates
The strong H₂SO₃hydrolyses disaccharides to liberate monosaccharides.
The monosaccharides get dehydrated to form furfural or hydroxyl methyl furfural which condenses with a-naphthol to form a violet-colored complex.

2. Benedict’s test:

This is a test for the identification of reducing sugars that form enediols.
The enediol forms of sugar reduce cupric ions of a yellow precipitate of cuprous hydroxide or a red precipitate of cuprous oxide.

3. Barfoed’s test:

“Common challenges in mastering disaccharide notes effectively: FAQs provided”

4. Osazone test:

Phenylhydrazine in acetic acid, when boiled with reducing sugars forms osazones.
The first two carbons are involved in this reaction.
The sugars that differ in their configuration on these carbons give the same type of osazones.
Maltose gives sunflower-shaped osazones while lactose powder – puff shaped.

“Factors influencing success with disaccharide studies: Q&A”

5. Sucrose hydrolysis test:

Sucrose can be hydrolyzed by concentrated ITCl, to be converted to glucose and fructose.
These are then reduced by Benedict’s test.

Normal blood glucose level:

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