LAS 1 Test

• Molisch test


  A chemical test that is used to check for the presence of carbohydrates in a given analyte<|>Formation of purple or purplish red ring = presence of carb<|>A positive reaction is given by almost all carbohydrates (exceptions include tetroses & trioses)
• Anthrone's test


  To detect carbohydrates in the given solution<|>Carbohydrate gets dehydrated when reacted with conc. H2SO4 to form furfural<|>Furfural reacts with anthrone to give a bluish-green colored complex<|>Positive test: all carbohydrates give test positive
• Iodine test

  To detect the presence of complex carbohydrates<|>This test is only given by starch<|>Starch reacts with iodine solution to form a complex blue color solution<|>The appearance of blue color solution confirms the presence of starch
• Seliwanoff's test


  Used to differentiate between aldose and ketose<|>Seliwanoff's reagent is a mixture of resorcinol and concentrated hydrochloric acid<|>Ketose = deep cherry red<|>Aldose = faint pink
• Bial Orcinol Test


  Chemical test to detect the presence of pentoses<|>Pentoses are dehydrated into furfural which condenses with orcinol to give a blue-green precipitate or bluish precipitate<|>Blue-green or bluish = pentose<|>Green, red or brown = hexose
• Mucic Acid Test

  Tests for lactose and galactose<|>Crystals = galactose<|>No crystal = no galactose
• Osazone Test


  A type of biochemical test which is used to detect reducing sugars<|>Can distinguish between different types of reducing sugars by the appearance time of the complex<|>Osazone crystals formed can take on different shapes depending upon the type of carbohydrate
• Fehling's Test

  This test is given by reducing sugars<|>The formation of red precipitate confirms the presence of reducing sugars
• Barfoed's Test

  To detect reducing carbohydrates<|>To distinguish reducing monosaccharides from disaccharides<|>Red precipitate = reducing monosaccharides<|>If color appears within first few minutes, sample contains reducing monosaccharides<|>If color appears later than 3 minutes, sample is of reducing disaccharides
• Benedict's Test


  To detect the presence of simple carbohydrates in an unidentified analyte<|>Can be used to check for reducing sugars that hold free aldehyde or ketone functional groups<|>The reducing sugar can be either a monosaccharide or a disaccharide<|>The "hotter" the final color of the reagent, the higher the concentration of reducing sugar
• Covalent bonding is the sharing of pairs of electrons between atoms.
• Carbohydrates

  Substances made up of carbon, hydrogen, & oxygen with a ratio of hydrogen to oxygen the same as in water (2:1)
• Large group of organic compounds occurring in foods & living tissues


  • Sugars
  • Starch
  • Cellulose
• Carbohydrates

  Can be polyhydroxyaldehydes (aldoses) or polyhydroxyketones (ketoses)
• Carbohydrates

  Polyhydric alcohols with active aldehyde or ketone groups & are called aldoses or ketoses based on these groups
• 4 classes of carbohydrates

  • Monosaccharides
  • Disaccharides
  • Oligosaccharides
  • Polysaccharides
• Monosaccharides


  Sugars with 1 molecule, cannot be hydrolyzed further, building blocks of carbohydrates
• Monosaccharides

  • Glucose
  • Fructose
  • Galactose
• Disaccharides

  Sugars with 2 monosaccharides covalently bonded
• Disaccharides


  • Sucrose
  • Lactose
  • Maltose
• Oligosaccharides


  Sugars with 3 monosaccharide units
• Oligosaccharides


  • Raffinose
• Polysaccharides


  Contains many monosaccharides
• Polysaccharides


  • Starch
  • Glycogen
  • Cellulose
  • Chitin
• Polysaccharides


  Storage of energy (starch in plants, glycogen in animals)<|>Structural component (cellulose in plants, chitin in anthropods)<|>Frequently found in combination with proteins (glycoproteins/mucoproteins) or lipids (lipopolysaccharides)
• Ribose


  1. carbon monosaccharide, important component of coenzymes (ATP, FAD, NAD) and the backbone of the genetic molecule RNA
• Saccharides and their derivatives include crucial biomolecules involved in the immune system, fertilization, preventing pathogenesis, blood clotting, and development
• Glycogen


  The main storage form of carbohydrate in the mammalian body, mainly in the liver (up to 6-8%) and muscles (1%, but muscles hold 3-4x more due to larger mass), a branched homoglycan made of α-D-glucopyranose units linked by α-1,4 and α-1,6 bonds
• In plants, stored energy is in the form of starch. In animals and fungi, it is glycogen, which is more compact and branches every 12 to 14 glucose residues
• Liver glycogen


  Releases glucose into the blood when levels drop, maintaining proper glucose concentration for 12-18 hours
• Blood glucose concentration normally ranges from 4.4 to 6.7 mmol/l (80-120 mg/dl)
• Polysaccharides


  Synthesized by plants, animals, & humans to be stored for food, structural support/metabolized for energy
• Starch


  The polysaccharide that plants store glucose as, found in cereal grains (wheat, rice, corn, oats, & barley) and tubers such as potatoes
• 2 fractions of starch

  • Amylose
  • Amylopectin
• Amylose


  A straight-chain polymer of D-glucose units linked by 1,4-glycosidic bonds, constitutes 20-30% of starch, soluble in water and can be hydrolyzed into glucose units by the enzymes α- amylase, forms a colloidal dispersion in hot water
• Amylopectin


  A branched-chain polymer of D-glucose units linked by α-1,4-glycosidic bonds and α-1,6-glycosidic bonds, constitutes 70-80% of starch, is completely insoluble
• All of the monomer units in starch are alpha-D-glucose, & all alpha-acetal links connect carbon no. 1 (C1) of 1 glucose to carbon no. 4(C4) of the next glucose
• Molisch Test


  Used to detect carbohydrates, including monosaccharides, disaccharides, oligosaccharides, & polysaccharides. Positive result: a violet or purple ring forms between the acid & the solution, indicating carbohydrates are present
• Anthrone Test


  Used to detect carbohydrates, including monosaccharides, disaccharides, oligosaccharides, & polysaccharides. Provides a rapid & convenient method for quantification of carbohydrates that are either free/bound to any lipids/proteins. Positive result: turns blue-green if carbohydrates are present
• Iodine Test


  Detects the presence of starch. Positive result: turns blue-black/blue-purple in the presence of starch