MT1 Biochemistry Lecture/Midyear Carbohydrates PDF

CHAPTER 4: Carbohydrates (p.64 - 94) so, a more, satisfactory definition of carbohydrates is “a group of polyhydroxy TOPIC OUTLINE aldehydes or ke...

CHAPTER 4: Carbohydrates (p.64 - 94) so, a more, satisfactory definition of carbohydrates is “a group of polyhydroxy TOPIC OUTLINE aldehydes or ketones” I. Definition ○ aldehyde or ketone derivatives of Importance of polyhydric alcohols, and are therefore Carbohydrates in plants aldoses or ketoses, accordingly Carbohydrates II. Classification carbohydrates form a class of organic compounds that include sugars, starch, and Monosaccharides Polysaccharides cellulose Oligosaccharides they occur in every living organism and are III. C-Chemical Structure of Carbohydrates essential to life, such as: Representative ○ sugar and starch (in foods) Asymmetric Compounds from ○ cellulose (in wood) Carbon Atom Aldose and Ketose ○ paper and cotton Sugar Structures III. Isomers in Carbohydrates IMPORTANCE OF CARBOHYDRATES Common Types carbohydrates are important in every living Mutarotation organisms as source of metabolic energy and of Isomers V. Reactions of Carbohydrates (done) also form part of a number of important Osazone Formation Amino Sugars molecules and structures Oxidation Esterification they occur as simple sugars but the largest Reduction Action of Alkali portion is encountered in the bound form Alcoholic ○ glycoproteins → simple sugar & protein Fermentation ○ glycolipids → simple sugar & lipids ○ nucleic acids → simple sugar & purine VI. Color Reactions ○ coenzymes → simple sugar & Molisch Test Tauber’s Benzidine Test other structures Moore’s Test Bial’s Orcinol-HCl Test Barfoed’s Test Iodine Test CARBOHYDRATES IN PLANTS Fehling’s Test and Seliwanoff’s test or carbohydrates are formed in plants by a process Benedict’s Test Resorcinol Test called photosynthesis VII. Carbohydrate Derivatives ○ plant cells take CO2 from air and water Phosphoric Acid from the ground and combine them in the Esters of Sugar Acids presence of sunlight and chlorophyll to Monosaccharides produce monosaccharides at the same Amino Sugars Deoxy Sugars time, giving off O2 into the air plant cells have the ability to convert DEFINITION monosaccharide to disaccharides and polysaccharides when carbohydrates are catabolized in the body, CARBOHYDRATES CO2 and O2 are formed means “hydrate of carbon” are generally considered as substances made up of carbon, hydrogen, and oxygen in which the proportion of hydrogen and oxygen is the same as that found in a molecule of water (2:1) however, there are substances like acetic acid (C2H4O2), lactic acid (C3H6O3), etc; in which such proportion of hydrogen an oxygen exists, and yet they are definitely not carbohydrates on the other hand, there are true carbohydrates, like rhamnose (C6H12O5) where the hydrogen and oxygen are not in such proportion 1  CLASSIFICATION they are the main energy-producing compounds of the body MONOSACCHARIDES mono = one simple sugars containing one saccharide group (one sugar molecule) simple sugars that cannot be changed into simple sugars upon hydrolysis binds with glycosidic bond molecular formula = CnH2nOn aldopentose → five-carbon simple BASED ON FUNCTIONAL GROUP sugar containing an aldehyde group ketohexose → six-carbon simple has an aldehyde group sugar containing a ketone group (-C) EXAMPLE glucose → C6H12O6 Aldoses glyceraldehyde, erythrose, ○ most important ribose, xylose, ribose, monosaccharide arabinose, glucose, ○ normally found in the galactose, mannoheptose bloodstream and in the tissue has a ketone group (-C-) fluids EXAMPLE ○ requires no digestion and can dihydroxyacetone, be given intravenously to Ketoses erythrulose, rhamnose, patients who are unable to mannose, fructose, take food by mouth mannoheptulose ○ known as blood sugar, grape Definition sugar, dextrose BASED ON THE NO. OF C-ATOMS ○ is found in the urine of has 3 C-atoms → C3H6O3 patients suffering from Trioses EXAMPLE diabetes mellitus and is an (C3H6O3) glyceraldehydes, indication of this disease. The dihydroxyacetone presence of glucose in the has 4 C-atoms → C4H8O4 Common urine is called glycosuria Tetroses Sugars ○ it is found along with fructose EXAMPLE (C4H8O4) in many fruit juices erythrose, erythrulose has 5 C-atoms → C5H10O5 fructose → C6H12O6 Pentoses EXAMPLE ○ called levulose or fruit sugar (C5H10O5) xylose, ribose, ○ occurs naturally in fruit juices arabinose, rhamnose and honey ○ can be formed in the has 6 C-atoms → C6H12O6 hydrolysis of sucrose Hexoses EXAMPLE (glucose + fructose), a (C6H12O6) glucose, galactose, disaccharide, and insulin, a mannose, fructose polysaccharide has 7 C-atoms → C7H14O7 ○ the most soluble and the Heptoses EXAMPLE sweetest of all sugars, being (C7H14O7) mannoheptose, 75% sweeter than glucose mannoheptulose galactose → C6H12O6 ○ formed in the hydrolysis of hexoses are the body’s most lactose (galactose + common carbohydrate because glucose), a disaccharide 2  ○ manufactured in the raffinose mammary glands from glucose during lactose formation ○ major component of glycolipids OLIGOSACCHARIDES di = two; tri = three; oligo = few or little simple sugars containing more than sucrose → glucose + fructose one saccharide groups (two-to-ten ○ commonly known as sugar molecules), joined by a “cane sugar” glycosidic linkage/bond ○ the sugar used ordinarily in ○ glycosidic bond (-O-) → the the home (table sugar) bond that links 2 ○ occurs in sorghum, Common monosaccharide units to form pineapple, and carrot roots Sugars a disaccharide ○ produced commercially from ○ each glycosidic bond is sugar cane and sugar beets classified as L or B and is lactose → glucose + galactose numbered according to the ○ commonly known as position of the C atoms it “milk sugar”; present in milk links ○ fermentation of lactose forms only disaccharides are of lactic acid which causes biochemical significance souring of milk maltose → glucose + glucose A. BASED ON REDUCING SUGAR ○ commonly known as possesses a free “malt sugar” ketone or an ○ present in germinating grain Reducing aldehyde group Definition Sugars ○ produced commercially by EXAMPLE hydrolysis of starch maltose, lactose do not possess a free POLYSACCHARIDES ketone or an poly = many Non-Reducing aldehyde group simple sugars containing more than Sugars ten saccharide groups EXAMPLE sucrose, raffinose (