Biology MONOSACCHARIDES AND DISACCHARIDES

Enzymes

• Enzymes are proteins that act as biological catalysts.
• Enzymes lower the activation energy of chemical reactions.

Amylase

• Amylase is an enzyme that breaks down starch into simple sugars.
• Amylase catalyzes hydrolysis of starch.

Catalase

• Catalase is a common enzyme found in most living organisms exposed to oxygen.
• Catalase breaks down hydrogen peroxide into water and oxygen.

Pancreatin

• Pancreatin is a mixture of digestive enzymes.
• Pancreatin is produced by the pancreas.
• Contains amylase, lipase, and protease.

Carbohydrate Classification

• Carbohydrates are classified into four groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
• Monosaccharides are simple sugars, consisting of one sugar unit.
• Disaccharides are composed of two monosaccharide units.
• Oligosaccharides contain a few monosaccharide units, typically 2 to 10.
• Polysaccharides are polymers of simple sugars with more than 10 monosaccharide units.

Common Monosaccharides

• Glucose is the main blood sugar and the primary energy source for cells.
• Galactose is an isomer of glucose, known as "brain sugar" for its role in infant brain development.
• Fructose is a fruit sugar, the sweetest naturally occurring carbohydrate, and the simplest ketose.

Disaccharides

• Disaccharides are formed when two monosaccharides are linked by an acetal bond.
• Maltose is composed of two glucose units linked by an α(1-4) glycosidic bond, found in malt, the juice from germinated barley, and other cereal grains.
• Lactose, the primary sugar in milk, is composed of galactose and glucose linked by a β(1-4) glycosidic bond.
• Sucrose, or table sugar, is composed of fructose and glucose linked by a β(2-1) glycosidic bond.

Carbohydrate Tests

• Seliwanoff's Test differentiates ketohexoses from aldohexoses. Ketohexoses react faster with concentrated HCl to form furfural derivatives, which form deep red complexes with resorcinol.
• Phenylhydrazine Reaction involves reaction with phenylhydrazine to form a phenylhydrazone. Aldoses and ketoses produce needle-shaped yellow osazone crystals.
• Phloroglucinol-HCl Test uses concentrated HCl to form furfural derivatives, specifically identifying galactose and lactose.

General Carbohydrate Tests

• Molisch Test is a general test for carbohydrates. α-Naphthol reacts with furfural or its derivatives from sugar dehydration in concentrated sulfuric acid, producing a colored product.
• Moore's Test detects carbohydrates in the presence of concentrated alkali.

Reduction Tests

• Fehling's Test uses alkaline cupric hydroxide. Reducing sugars reduce it to yellow or red cuprous oxide, indicating their presence.
• Benedict's Test is similar to Fehling's, but uses different reagents.
• Tollen's Test (Silver Mirror Test) distinguishes aldehydes from ketones due to aldehydes' easier oxidation.
• Barfoed's Test oxidizes monosaccharides but not disaccharides, useful for distinguishing them.
• Trommer's Test involves acid hydrolysis of disaccharides to form monosaccharides, similar to Benedict's.
• Nylander's Test uses bismuth subnitrate, which forms a black precipitate with reducing sugars.
• Picric Acid Test uses picric acid to react with reducing sugars, forming a mahogany red solution.