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CARBOHYDRATES

CARBOHYDRATES. Bodies main energy source CH 2 O Only plants synthesise carbohydrates Starch , Cellulose ( polysaccharides ) Lactose , sucrose ( dissaccharides ) Glucose , fructose ( monosaccharides ). Monosaccharides. (CH 2 O) n where n=3 to 9

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CARBOHYDRATES

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  1. CARBOHYDRATES • Bodiesmainenergysource • CH2O • Onlyplantssynthesisecarbohydrates • Starch, Cellulose (polysaccharides) • Lactose, sucrose (dissaccharides) • Glucose, fructose (monosaccharides)

  2. Monosaccharides • (CH2O)nwhere n=3 to 9 • Aldehydesorketonescontaining a carbonylgroup and at least 2 hydroxylgroups • Hexoses (glucose, galactose, fructose)

  3. Pentoses • Contain 5 carbonatoms • Ribose

  4. Properties of Mono and di-saccharides • Low molar masses • Sweet • Soluble in water • Crystallinesolids • Reducingsugars (aldehydegroupoxidised)

  5. Structure of Glucose

  6. Interconversion of α and βglucose

  7. Straightchain and cyclicfructose

  8. Condensation of Monosaccharides

  9. Disaccharideformation • Β-glucose + β-galactose -----> lactose • α-glucose + α-glucose -------> maltose • α-glucose + β-fructose ------> sucrose

  10. Polysaccharides • Numerousmonosaccharideunits • Largemasses • Notsweet, non-reducing, insoluble • Starchisplantstoreforglucose • Twoforms : • Amylose (water soluble) • Amylopectin (water insoluble)

  11. Amylose • α-1,4 glycosidiclinkages

  12. Amylopectin • α-1,4 glycosidiclinkages as well as α-1,6 glycosidiclinkages

  13. Glycogen • More highlybranchedthanamylopectinbutalso has α-1,4 glycosidiclinkages as well as α-1,6 glycosidiclinkages

  14. Cellulose • Linear • Made up of β-glucoseunitswithallglycosidiclinkages in the 1, 4-position • Extensivehydrogenbondingbetweenchains • Strength, rigidity • Insoluble

  15. MajorFunctions of Carbohydrates • EnergySource • Energy Reserve (e.g. glycogen) • Precursor of otherBiologicallyImportantMolecules (e.g. anticoagulants, components of nucleicacids)

  16. DietaryFibre • Plant material • Cannot be digestedbyhumans • Parts of fruits, vegetables, grains • May be digestedby bacteria in gut • Cellulose • Lignin • Pectin

  17. Importance of High FibreDiet • Constipation and Diverticulosis • Irritable bowelsyndrome • Obesity • Crohn´sDisease • Haemorrhoids

  18. Reading and questions • Pleasereadpages 331 to 334, allaboutcarbohydrates. • Takeyourown notes. • Make a mindmap. • Can youanswerthequestions in theorange boxes (B.3.1 etc) ? • Nowanswerquestions 9 to 16 on page 359.

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