TAILIEUCHUNG - Lecture Principles of biochemistry - Chapter 8 (part 1): Carbohydrates: monosaccharides

After studying this chapter you will be able to: Know functional roles of carbohydrates; know carbohydrate classifications; know the differences between aldoses and ketoses; be able to identify chiral carbons in monsaccharides; be able to calculate the number of possible stereoisomers for a given monosaccharide; define enantiomer, epimer, diastereomer; understand how hemiacetal and hemiketal formation occurs and how this relates to sugar cyclization. | Chapter 8 (part 1) Carbohydrates Carbohydrates Most abundant class of biological molecules on Earth Originally produced through CO2 fixation during photosynthesis Roles of Carbohydrates Energy storage (glycogen,starch) Structural components (cellulose,chitin) Cellular recognition Carbohydrate derivatives include DNA, RNA, co-factors, glycoproteins, glycolipids Carbohydrates Monosaccharides (simple sugars) cannot be broken down into simpler sugars under mild conditions Oligosaccharides = "a few" - usually 2 to 10 Polysaccharides are polymers of the simple sugars Monosaccharides Polyhydroxy ketones (ketoses) and aldehydes (aldoses) Aldoses and ketoses contain aldehyde and ketone functions, respectively Ketose named for “equivalent aldose” + “ul” inserted Triose, tetrose, etc. denotes number of carbons Empirical formula = (CH2O)n Monosaccharides are chiral Aldoses with 3C or more and ketoses with 4C or more are chiral The number of chiral carbons present in a ketose is always one less than the number found in the same length aldose Number of possible steroisomers = 2n (n = the number of chiral carbons) Stereochemistry Enantiomers = mirror images Pairs of isomers that have opposite configurations at one or more chiral centers but are NOT mirror images are diastereomers Epimers = Two sugars that differ in configuration at only one chiral center Cyclization of aldose and ketoses introduces additional chiral center Aldose sugars (glucose) can cyclize to form a cyclic hemiacetal Ketose sugars (fructose) can cyclize to form a cyclic hemiketal Haworth Projections Anomeric carbon (most oxidized) -OH up = beta -OH down = alpha 1 2 3 4 5 6 For all non-anomeric carbons, -OH groups point down in Haworth projections if pointing right in Fischer projections Monosaccharides can cyclize to form Pyranose / Furanose forms a = 64% b = 36% a = b = a = b = Conformation of Monosaccharides Pyranose sugars not planar molecules, prefer to be in either of the two chair conformations. Reducing Sugars When in the uncyclized form, monosaccharides act as reducing agents. Free carbonyl group from aldoses or ketoses can reduce Cu2+ and Ag+ ions to insoluble products Derivatives of Monosaccharides Sugar Phosphates Deoxy Acids Amino Sugars Sugar alcohols Monosaccharide structures you need to know Glucose Fructose Ribulose Glyceraldehyde Dihydroxyacetone

• Sinh học
• Principles of biochemistry
• Lecture Principles of biochemistry
• Nguyên lý hóa sinh
• Biochemical compounds
• Conformation of monosaccharides
• Carbohydrate classifications
• Ebook Principles of biochemistry
• Principles of biochemistry (4th edition)
• The glyoxylate cycle
• Fatty acid catabolism
• Electron Transfer reactions
• Evolutionary foundations
• Protein interactions modulated
• Nucleic acid structure
• Biological systems
• Biological macromolecules
• Chemical principles
• Properties of water
• Hydrogen bonding
• Amino acids
• Amino acid structure
• Protein purification
• Cell extract
• Protein classification
• Protein 3 Dimensional structure
• Protein folding
• Protein 3 D structure
• 3 D structure
• Oxygen binding curve
• Enzyme kinetics
• Rate constants
• Catalytic Power
• Classes of enzymes
• Inhibitor kinetics
• Enzyme regulation
• Allosteric regulation
• Enzyme action
• Mechanisms of enzyme action
• Ions Cofactors
• Metal ion
• Biotin cofactor
• Oligo carbohydrate
• Polysaccharides carbohydrate
• Lipid subclasses
• Acyl lipids
• Fluid mosaic model
• membrane transporters
• Metabolism proceed
• Anaeorbic process
• Triose Phosphate Isomerase
• Regulation of glycolysis
• Control points in glycolysis
• Citric acid cycle
• TCA cycle