Carbohydrates and Simple Sugars

Carbohydrates

• Carbohydrates are compounds with the general formula Cx(H₂O)x.
• They are also called saccharides.
• Monosaccharides are simple sugars, including glucose, fructose, ribose, galactose, and glyceraldehyde.
• Glucose and fructose have the formula C₆H₁₂O₆.
• Ribose has the formula C₅H₁₀O₅.
• Glyceraldehyde has the formula C₃H₆O₃.
• Aldehydes are aldoses; ketones are ketoses.
• Monosaccharides are classified by the number of carbons (triose, tetrose, pentose, hexose, heptose, and so on).
• Common sugars include glucose, fructose, galactose, and their derivatives.
• Different sizes of monosaccharides are detailed in image representations.

Common Sugars

• Glucose is an aldose.
• Fructose is a ketose.
• Glucose and fructose are both hexoses (6 carbons).
• Glucose chemical structure is shown.
• Fructose chemical structure is shown.

Simple Sugars

• Different types of simple sugars are detailed in image representations.
• Simple sugars, including D-ribose, D-glucose, D-fructose, D-galactose, and D-mannose, are shown.

Carbonyl on the End - D-Aldoses

• D-Glyceraldehyde is a 3-carbon aldose.
• D-Erythrose and D-Threose are 4-carbon aldoses, with images to illustrate their structure.

D-Aldoses

• D-Ribose, D-Arabinose, D-Xylose, and D-Lyxose are 5 carbon aldoses (pentoses), with image representations.
• D-Allose, D-Altrose, D-Glucose, D-Mannose, D-Gulose, D-Idose, D-Galactose, and D-Talose are 6-carbon aldoses (hexoses), with image representations.

Carbonyl Inner-Carbon D-Ketoses

• Dihydroxyacetone is a 3-carbon ketose.
• D-Erythrulose is a 4-carbon ketose.

D-Ketoses

• D-Ribulose, D-Psicose, D-Fructose, D-Xylulose, D-Sorbose, and D-Tagatose (with image representations of their structures).

Asymmetric Carbons

• Glyceraldehydes have asymmetric carbons. The carbons with multiple different groups attached are asymmetric.
• L-Glyceraldehyde and D-Glyceraldehyde are mirror images.

Multiple Asymmetric Centers

• Glucose has multiple asymmetric carbons.
• D-Glucose is one configuration around the asymmetric carbon.

Enantiomers

• Enantiomers are mirror images of each other.
• D-Glucose and L-Glucose are enantiomers.

Diastereomers

• Diastereomers have the same chemical type and size, but are not mirror images.
• D-Glucose and D-Gulose are diastereomers.

Epimers

• Epimers are diastereomers that differ in configuration at only one carbon.
• D-Glucose and D-Galactose are epimers.

Cyclization of Sugars

• Cyclization of sugars creates a hemiacetal or hemiketal.
• New asymmetric carbon is formed- the anomeric carbon.
• α-D-Fructofuranose and α-D-Fructopyranose are image examples of cyclic forms of fructose.
• Illustrated are examples of α- and β-furanose and pyranose forms of glucose and fructose.

Common Furanoses

• Fructose and Ribose are examples of common furanoses. β-D-Fructofuranose and β-D-Ribofuranose image representations.

Oxidation of Sugars-Reducing Sugars

• All monosaccharides and some disaccharides (lactose, maltose) are reducing sugars.
• A reducing sugar has an open-chain form with an aldehyde or can tautomerize in solution forming an aldehyde.

Basis of Fehling's Reaction - Glucose is Reducing

• Glucose, in its open-chain form, is a reducing sugar. A reaction with a copper (II) reagent (Cu²⁺) to a copper(I) (Cu⁺) precipitate.

Glucose Family, Amino Sugars, Deoxy Sugars, Acidic Sugars

• Detailed presentation of structural formulas.
• Various sugars, their structures, and different modified forms represented visually.

Disaccharides

• Sucrose (glucose + fructose), Lactose (glucose + galactose), and Maltose (glucose + glucose) are examples of disaccharides.

Formation of Glycosidic Bonds-Polysaccharides

• Polysaccharides are formed by glycosidic bonds.
• α-1,4 glycosidic links and Maltose formation are image representations.

Disaccharides-Lactose and Maltose

• Lactose (galactose + glucose) and Maltose (glucose + glucose) are examples of disaccharides.
• The glycosidic bonds, are shown as image representations.

Oligosaccharides

• Oligosaccharides play roles in cellular identity.
• Typically composed of 3-9 monosaccharide units and are often attached to biopolymers (proteins, lipids).

Oligosaccharides attached to Proteins

• O-linked sugars are added in the Golgi apparatus.
• N-linked sugars synthesis starts in the endoplasmic reticulum and is completed in the Golgi apparatus.

Polysaccharides (glycans)

• Cellulose, glycogen, amylose, amylopectin, and chitin are types of polysaccharides.
• Polysaccharides have various functions including energy storage, structural strength, and lubrication.
• Structural formulas for polysaccharide molecules are displayed.

Homopolysaccharides and Heteropolysaccharides

• Homopolysaccharides have one type of monomer (e.g., amylose).
• Heteropolysaccharides have more than one type of monomer (e.g., hemicellulose).
• These categories are illustrated with image representations.

Polysaccharides-Sugar Polymers

• Amylose, a component of starch, is an unbranched homopolysaccharide. Structural formulas are displayed.
• Cellulose is an unbranched homopolysaccharide. Structural formulas are displayed.

Structure of Amylopectin and Glycogen

• Amylopectin and glycogen are branched homopolysaccharides.
• Branch points are explained with diagrams.
• Glycogen has branch points every 8-12 residues; amylopectin branches every 30–50 residues are explained by diagrams.

Hemicellulose, Chitin

• Hemicellulose is a branched heteropolysaccharide. Its monomers are shown.
• Chitin is structurally similar to cellulose but with an acetylamine group.

Glycosaminoglycans (mucopolysaccharides)

• Examples include keratan sulfate, heparin, hyaluronic acid, and chondroitin sulfate.
• These are repeating disaccharide units with negatively charged residues.

Proteoglycans

• Proteoglycans are polysaccharides linked to proteins. They have larger sugar components.

Explore the world of carbohydrates in this quiz, focusing on their structures and types. Learn about monosaccharides, including glucose and fructose, and their classifications such as aldoses and ketoses. Test your knowledge of the different types and formulas of simple sugars.