Lecture Presentation Chapter 15 Carbohydrates Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 15 Carbohydrates Diabetes nurses help patients • learn to monitor their medication and blood sugar levels • look for symptoms like diabetic nerve damage and vision loss This requires knowledge of the endocrine system, as this system is often involved with obesity and other diseases General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 15 Readiness Core Chemistry Skills • Naming Alcohols and Phenols (13.1) • Writing Equations for the Oxidation of Alcohols (13.4) • Naming Aldehydes and Ketones (14.1) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 15.1 Carbohydrates Carbohydrates are • a major source of energy from our diet • made from the elements carbon, hydrogen, and oxygen • also called saccharides, which means “sugars.” Learning Goal Classify a monosaccharide as an aldose or a ketose, and indicate the number of carbon atoms General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Carbohydrates Carbohydrates, such as glucose, • are produced by photosynthesis in plants • are synthesized in plants from CO2, H2O, and energy from the sun • are oxidized in living cells to produce CO2, H2O, and energy General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Types of Carbohydrates The types of carbohydrates are • monosaccharides, the simplest carbohydrates; • disaccharides, which consist of two monosaccharides; and • polysaccharides, which contain many monosaccharides General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Monosaccharides Monosaccharides • contain several hydroxyl groups attached to a chain of three to eight carbon atoms • that contain an aldehyde group are classified as aldoses • that contain a ketone group are classified as ketoses • have hydroxyl groups on all carbons except the carbonyl carbon General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Types of Monosaccharides Monosaccharides are also classified by the number of carbon atoms present triose (three C atoms) tetrose (four C atoms) pentose (five C atoms) hexose (six C atoms) An aldopentose is a five-carbon saccharide with an aldehyde group A ketohexose is a six-carbon saccharide with a ketone group General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Types of Monosaccharides General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify each as aldo or keto and as tetrose, pentose, or hexose A B General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Melibiose is a disaccharide that is 30 times sweeter than sucrose A What are the monosaccharide units in melibiose? B What type of glycosidic bond links the monosaccharides? C Identify the structure as α- or β-melibiose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Melibiose is a disaccharide that is 30 times sweeter than sucrose A What are the monosaccharide units in melibiose? α-D-galactose and α-D-glucose B What type of glycosidic bond links the monosaccharides? α-(1 6)-glycosidic bond C Identify the structure as α- or β-melibiose α-melibiose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 15.6 Polysaccharides The polysaccharide cellulose is composed of glucose units connected by β-(1 4)-glycosidic bonds Learning Goal Describe the structural features of amylose, amylopectin, glycogen, and cellulose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Polysaccharides Polysaccharides • are formed when many monosaccharides are joined together • include amylose, amylopectin, cellulose, and glycogen, which are polymers of D-glucose and differ by branching and types of glycosidic bonds General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake α-D-Glucose © 2016 Pearson Education, Inc Starch Starch is • a storage form of glucose in plants, found as insoluble granules in rice, wheat, potatoes, beans, and cereals • composed of two kinds of polysaccharides: amylose and amylopectin General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Starch: Amylose Amylose, which makes up about 20% of starch, consists of 250 to 4000 α-D-glucose molecules connected by α-(1 4)-glycosidic bonds in a continuous chain Polymer chains of amylose are coiled in a helical fashion General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Starch: Amylopectin Amylopectin • makes up as much as 80% of starch • is a branched-chain polysaccharide • contains glucose molecules connected by α-(1 and α-(1 6)-glycosidic bonds 4)- Starches hydrolyze easily in water and acid to give smaller saccharides, called dextrins, which then hydrolyze to maltose and finally glucose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Starch: Amylopectin In our bodies, these complex carbohydrates • are digested by the enzymes amylase in saliva and maltase in the intestines • provide about 50% of our nutritional calories from the glucose obtained in digestion General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Animal Starch: Glycogen Glycogen is • a polymer of glucose that is stored in the liver and muscle of animals • hydrolyzed in our cells at a rate that maintains the blood level of glucose and provides energy between meals • similar to amylopectin but more highly branched The glucose units in glycogen are joined by α-(1 4)glycosidic bonds, with branches attached by α-(1 6)glycosidic bonds that occur every 10–15 glucose units General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Cellulose Cellulose, the major structural unit of wood and plants, • is a polysaccharide of glucose units in unbranched chains with β-(1 4)-glycosidic bonds • cannot form hydrogen bonds with water, making it insoluble in water • gives a rigid structure to the cell walls in wood and fiber • is more resistant to hydrolysis than are the starches • cannot be digested by humans because humans cannot break down β-(1 4)-glycosidic bonds General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Cellulose The polysaccharide cellulose is composed of glucose units connected by β(1 4)glycosidic bonds General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify the polysaccharides and types of glycosidic bonds in each of the following: A B General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Identify the polysaccharides and types of glycosidic bonds in each of the following: A Cellulose β-(1 4)-glycosidic bonds B Amylose α-(1 4)-glycosidic bonds Amylopectin α-(1 4)- and α-(1 6)-glycosidic bonds General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Concept Map General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... group General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Types of Monosaccharides General, Organic, and Biological Chemistry: Structures. .. D Core Chemistry Skill Identifying D- and L-Fischer Projections General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc D and L Isomers:... dizziness, general weakness, and muscle tremors • a diet may be prescribed that consists of several small meals high in protein and low in carbohydrates General, Organic, and Biological Chemistry: Structures