Carbohydrates Larry Emme Chemeketa Community College 1 Chapter Outline Monosaccharides Fischer Projections Haworth Structures Diasaccharides Polysaccharides Carbohydrates Carbohydrates are a major source of energy from our diet. composed of the elements C, H, and O. also called saccharides, which means sugars.
3 Carbohydrates Carbohydrates are produced by photosynthesis in plants. such as glucose are synthesized in plants from CO2, H2O, and energy from the sun. are oxidized in living cells to produce CO2, H2O, and energy. 4 Types of Carbohydrates The types of carbohydrates are monosaccharides, the simplest carbohydrates. disaccharides, which consist of two monosaccharides. polysaccharides, which contain many monosaccharides.
5 Chapter 14 Carbohydrates Monosaccharides 6 Monosaccharides Monosaccharides consist of 3-6 carbon atoms typically. a carbonyl group (aldehyde or ketone). several hydroxyl groups. 7 Aldoses -CHO condensed Aldoses are monosaccharides with an aldehyde group.
many hydroxyl (-OH) groups. triose (3 C atoms) tetrose (4 C atoms) pentose (5 C atoms) hexose (6 C atoms) O aldose C H H C OH H
C OH CH 2OH Erythose, an aldotetrose 8 Ketoses Ketoses are monosaccharides with a ketone group. many hydroxyl (-OH) groups. CH2OH C=O
ketose H COH H COH HCOH CH2OH Fructose, a ketohexose 9 Fischer Projections Chapter 14 Carbohydrates of Monosaccharides CH 2OH CHO O
H C H H C OH HO O OH H HO H HO C H H C OH H C OH
H OH H OH H OH H OH CH2OH Glucose CH 2OH
CH 2OH Fructose 10 Fischer Projections Chapter 14 Carbohydrates of Monosaccharides CH 2OH CHO H HO O OH H H
OH H OH CH 2OH HO H H OH H OH CH 2OH Glucose
Fructose 11 Fischer Projections A Fischer projection is used to represent carbohydrates. Emil Fischer places the most oxidized group at the top. 1852-1919 shows chiral carbons as the intersection of vertical (goes back from you) and horizontal (comes out towards you) lines. 12 Governor Kate Governor Kate (Twin) 13
Governor Kate Fringe Governor Kate 14 D and L Notations In a Fischer projection, the OH group on the chiral carbon farthest from the carbonyl group (2nd from bottom) determines an L or D isomer. left is assigned the letter L for the L-form. right is assigned the letter D for the D-form. 15 Examples of D and L Isomers of Monosaccharides O
O C H HO H C O OH C H H H OH
H OH H OH H OH H OH CH 2OH D-Glucose CH 2OH D-Ribose
HO H H H OH H OH HO H CH 2OH L-Galactose 16
Learning Check Identify each as the D or L isomer. A. B. C. CH2OH O H HO H H HO H
HO __-Ribose HO C H HO CH2OH O O C H OH H
OH H H OH CH2OH __- Threose H CH2OH __- Fructose 17 Solution Identify each as the D or L isomer.
A. B. C. CH2OH O C H HO H HO H H HO H
HO CH2OH L-Ribose O O C H HO H OH H OH
H H OH CH2OH L-Threose CH2OH D-Fructose 18 D-Glucose D-glucose is found in fruits, corn syrup, and honey.
an aldohexose with the formula C6H12O6. known as blood sugar in the body. the monosaccharide in polymers of starch, cellulose, and glycogen. O H C H C OH HO C H H C OH H C OH CH2OH 19
Blood Glucose Level In the body, glucose has a normal blood level of 70-90 mg/dL. a glucose tolerance test measures blood glucose for several hours after ingesting glucose. 20 D-Fructose D-Fructose is a ketohexose, C6H12O6. is the sweetest carbohydrate. is found in fruit juices and honey. converts to glucose in the body. CH2OH C O
HO H H OH H OH CH2OH D-Fructose 21 D-Galactose D-Galactose is an aldohexose, C6H12O6.
is not found free in nature. is obtained from lactose, a disaccharide. has a similar structure to glucose except for the OH on carbon 4. O C H H OH HO H HO
H H OH CH2OH D-Galactose 22 Haworth Structures of Chapter 14 Carbohydrates Monosaccharides 6 CH2OH 5 4 Sir (Walter) Norman
Haworth 1883-1950 OH O 1 OH 2 3 OH OH 23 Cyclic Structures Cyclic structures are the prevalent form of monosaccharides with 5 or 6 carbon atoms. O
O form when the hydroxyl group on carbon 5 reacts with the aldehyde group or ketone group. 24 Drawing the Cyclic Structure for Glucose STEP 1: Number the carbon chain and turn clockwise to form a linear open chain. H O C 1 H C OH H 2
HO 3C H H 4C OH H 5C OH 6CH H OH H O HOCH2 C C C C C 6 5 4 3 2 1
H OH OH H OH 2OH 25 Cyclic Structure for Glucose STEP 2: Fold clockwise to make a hexagon. Bond the carbon 5 O to carbon 1. Place the carbon 6 group above the ring. Write the OH groups on carbon 2 and carbon 4 below the ring. Write the OH group on carbon 3 above the ring. Write a new OH on carbon 1. CH2OH
6 O 5 4 OH OH 3 1 2 OH OH 26 Cyclic Structure for Glucose
(continued) STEP 3: Write the new OH on carbon 1 down for the form. up for the form. CH2OH CH2OH O OH OH O OH OH -D-Glucose
OH OH OH OH -D-Glucose 27 Example of the Formation of Cyclic Glucose 28 OH O O H
O H 29 H OH O O H O H
30 -D-Glucose and -D-Glucose in Solution When placed in solution, cyclic structures open and close. -D-glucose converts to -D-glucose and vice versa. at any time, only a small amount of open chain forms. CH2OH CH2OH O OH OH OH OH -D-Glucose
(36%) H O OH O O C OH CH2OH H OH OH OH
OH D-Glucose (open) (trace) -D-GlucoseOH (64%) 31 Cyclic Structure of Fructose Fructose is a ketohexose. forms a cyclic structure. reacts the OH on carbon 5 with the C=O on carbon 2. CH2OH C O CH2OH
HO C H CH2OH D-Fructose CH2OH OH H C OH H C OH CH2OH O O OH OH
OH OH -D-Fructose CH2OH OH -D-Fructose 32 Chemical Properties of Monosaccharides 33 Reducing Sugars Reducing sugars are monosaccharides that oxidize to give a carboxylic acid. undergo reaction in the Benedicts test.
include the monosaccharides glucose, galactose, and fructose. 34 Oxidation of D-Glucose O O C H C OH H C OH H C OH HO H H H OH
OH CH2OH D-Glucose 2+ + 2Cu (blue) [O] HO H H OH H
OH + 2Cu2O (red) CH2OH D-Gluconic acid 35 Reduction of Monosaccharides The reduction of monosaccharides involves the carbonyl group. produces sugar alcohols, or alditols. such as D-glucose gives D-glucitol, also called sorbitol.
36 Learning Check Write the products of the oxidation and reduction of D-mannose. O C H HO H HO H H OH H
OH CH2OH D-Mannose 37 Solution Write the products of the mild oxidation and reduction of D-mannose. D-Mannitol D-Mannose D-Mannonic acid 38 Chapter 14 Disaccharides Carbohydrates
sucrose Maltose (malt sugar) lactose 39 Allana Mitchell 5/2/14 40 Important Disaccharides A disaccharide consists of two monosaccharides. Monosaccharides Disaccharide Glucose + glucose
maltose + H2O Glucose + galactose lactose + H2O + fructose Glucose sucrose + H2O 41 Maltose Maltose is a disaccharide also known as malt sugar. composed of two D-glucose molecules. obtained from the hydrolysis of starch. linked by an -1,4-glycosidic bond formed from the OH on carbon 1 of the first glucose and
OH on carbon 4 of the second glucose. used in cereals, candies, and brewing. found in both the - and -forms. 42 Formation of Maltose -Form 43 Lactose Lactose is a disaccharide of D-galactose and - or -D-glucose. contains a -1,4glycosidic bond. is found in milk and milk products. 44
Sucrose Sucrose or table sugar is obtained from sugar cane and sugar beets. consists of -D-glucose and -D-fructose. has an ,-1,2-glycosidic bond. 45 Sweetness of Sweeteners Sugars and artificial sweeteners Relative Sweetness of Sugars and Artificial Sweeteners differ in sweetness. are compared to sucrose (table sugar), which is assigned a value of 100.
46 Relative Sweetness of Sugars and Sugar Substitutes based on fructose = 100 Sugars Relative sweetness Sugar substitutes Fructose 100 Sucralose (Splenda) 35000 Invert Sugar
58 Asparatame (Equal) Rebiana (Truvia, PureVia) Relative sweetness 10000 12000 47 Discovered in 1976 Discovered in 1879 Discovered in 1967
Discovered in 1965 Agave nectar (sometimes called agave syrup) is most often produced from the Blue Agaves that thrive in the volcanic soils of Southern Mexico. Agaves are large, spikey plants that resemble cactus or yuccas in both form and habitat, but they are actually succulents similar to the familiar Aloe Vera. To make the agave nectar, sap is extracted from the pina, filtered, and heated at a low temperature, which breaks down the carbohydrates into sugars. Lighter and darker varieties of agave nectar are made from the same plants. Because of the low temperatures used in processing many varieties (under 118F) raw foods enthusiasts generally regard agave nectar as a raw food. http://www.allaboutagave.com/
The taste of agave nectar is comparable, though not identical, to honey. Many people who do not like the taste of honey find agave a more palatable choice. It also has none of the bitter aftertaste associated with artificial sweeteners. Stevia (sweetleaf, sweet leaf or sugarleaf) This sweetener is made from a crude preparation (powder or liquid) of dried stevia leaves. It may contain a mixture of many substances, only some of which are sweet. Truvia natural sweetener is made from rebiana, the best tasting part of the stevia leaf, erythritol and natural flavors. Rebiana is the common or usual name for a food-grade high-purity extract of the stevia leaf that is at least 97 percent rebaudioside-A, the best tasting sweet substance found in the stevia leaf.
Chemically, erythritol is simply a four-carbon sugar alcohol. Erythritol is made by fermenting glucose then separating and purifying the resulting product. Most fruits, berries and plants contain xylitol (also called wood sugar), the richest natural sources being plums, strawberries, raspberries, cauliflower and endives. Xylitol is extremely toxic to dogs The toxic dose of xylitol is 0.1 gm/kg body weight, while liver failure results from doses greater than 0.5 g/kg body weight. Translating these numbers into something usable in the every-day world is a little harder to do, since the amount of xylitol varies from one product to another. Two sticks of gum is enough to cause a serious drop in blood sugar for a small (under 20 lb) dog, while it might take 8 to 10 sticks to affect a large (over 60 lb) dog, but these amounts are only an estimate. As for
baked goods containing xylitol, again, the amount in each cookie or muffin will vary. In one case, a Standard Poodle died after eating 5 or 6 cookies sweetened with xylitol. The history of sodium cyclamate illustrates the difficulty in balancing consumer safety with the needs of the consumer market. This sweetener was banned in 1970 because of research that indicated risks of cancer from consuming the sweetener. Discovered in 1937 57 Chapter 14 Carbohydrates Polysaccharides
58 CH2OH Polysaccharides O 1 # Polysaccharides are polymers of D-glucose. include amylose and amylopectin, starches made of -D-glucose. include glycogen (animal starch in muscle), which is made of -Dglucose. include cellulose (plants and wood), which is made of -D-glucose. OH
OH OH OH -D-Glucose # -D-Glucose 1 59 Structures of Amylose and Amylopectin 60 Amylose Amylose is
a polymer of -Dglucose molecules. linked by -1,4 glycosidic bonds. a continuous (unbranched) chain. 62 Amylopectin Amylopectin is a polymer of -Dglucose molecules. is a branched-chain polysaccharide. has -1,4-glycosidic bonds between the glucose units. has -1,6 bonds to branches. 63 Glycogen
Glycogen is the polysaccharide that stores -D-glucose in muscle. is similar to amylopectin, but is more highly branched. 64 Cellulose Cellulose is a polysaccharide of glucose units in unbranched chains. has -1,4-glycosidic bonds. cannot be digested by humans because humans cannot break down -1,4glycosidic bonds. 65
Cellulose: stacked structure CH2OH O O CH2OH OH O O CH2OH OH OH O O CH2OH OH
OH O O OH OH O OH 66 67 The End End of Chapter Learning Checks Try these after you have reviewed the chapter Learning Check
What is the classification of the sugar below? a. b. c. d. e. aldotriose ketotriose aldotetrose ketotetrose ketopentose CH2OH C=O CH2OH 70 Learning Check Answers What is the classification of the sugar below? a.
b. c. d. e. aldotriose ketotriose aldotetrose ketotetrose ketopentose 1 CH2OH 2 C=O 3 CH2OH
71 Learning Check Write the projection formula for any D-aldopentose. 72 Learning Check Answers This is one example of a D-aldopentose. This molecule is a D-isomer because of the orientation of the hydroxyl group (see arrow). The molecule is an aldose because it is an aldehyde and a pentose because it contains five carbon atoms. H C O H
C OH HO C H H C OH CH2OH D-configuration 73 Learning Check
Classify the following as D- or L-monosaccharides and as aldoses or ketoses. CHO CH2OH CH2OH C O C O H C OH
H C OH H C OH HO C H H C
OH HO C H HO C H H C OH HO
C H H C OH CH2OH CH2OH CH2OH 74 Learning Check Answers Classify the following as D- or L-monosaccharides and as aldoses or ketoses. CHO
CH2OH CH2OH C O C O H C OH H C
OH H C OH HO C H H C OH HO
C H HO C H H C OH HO C H
H C OH CH2OH D-aldose CH2OH L-ketose CH2OH D-ketose 75 Learning Check Number the carbon atoms in the Fischer open-chain and the Haworth ring, #1 - #6, and then add the OH groups to all the ring carbons.
76 Learning Check Answers Number the carbon atoms in the Fischer open-chain and the Haworth ring, #1 - #6, and then add the OH groups to all the ring carbons. 1 6 2 5 3 4 5 6 4 1 OH
OH 3 2 OH OH 77 Learning Check Identify each carbohydrate described as one of the following: Amylose Cellulose Lactose Sucrose
a. A polysaccharide composed of many glucose units linked only by -1,4-glycosidic bonds. b. A sugar containing both glucose & galactose. c. A disaccharide that is reducing. d. A carbohydrate composed of glucose units joined by -1,4-glycosidic bonds. 78 Learning Check Answers Identify each carbohydrate described as one of the following: Amylose Cellulose Lactose Sucrose a. A polysaccharide composed of many glucose units linked only by -1,4-glycosidic bonds. Amylose b. A sugar containing both glucose & galactose. Lactose
c. A disaccharide that is reducing. Lactose d. A carbohydrate composed of glucose units joined by -1,4-glycosidic bonds. Cellulose 79 Learning Check Identify each carbohydrate described as one of the following: Glucose Lactose Sucrose Maltose a. A sugar containing both glucose & fructose. b. Also called table sugar. c. Found in milk & milk products. d. Gives sorbitol upon reduction. 80
Learning Check Answers Identify each carbohydrate described as one of the following: Glucose Lactose Sucrose Maltose a. A sugar containing both glucose & fructose. Sucrose b. Also called table sugar. Sucrose c. Found in milk & milk products. Lactose d. Gives sorbitol upon reduction. Glucose 81 Learning Check Identify each carbohydrate described as one of the following: Maltose Sucrose
Cellulose Glycogen a. A disaccharide that is not a reducing sugar. b. A disaccharide that occurs as a breakdown product of amylose c. The storage form of energy in humans. d. A carbohydrate that is used for structural purposes by plants. 82 Learning Check Answers Identify each carbohydrate described as one of the following: Maltose Sucrose Cellulose Glycogen
a. A disaccharide that is not a reducing sugar. Sucrose b. A disaccharide that occurs as a breakdown product of amylose. Maltose c. The storage form of energy in humans. Glycogen d. A carbohydrate that is used for structural purposes by plants. Cellulose 83
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