Biochem - Disaccharide PDF

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Disaccharide...

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TOPIC 12 ENHANCEMENT ACTIVITY/OUTPUT: Perform as indicated. 1. Which of the disaccharides maltose, cellobiose, lactose, and sucrose has each of the following structural or reaction characteristics? There may be more than one correct answer for a given characteristic. a. Two different monosaccharide units are present. Lactose, Sucrose b. Hydrolysis produces only monosaccharides. Lactose, Cellobiose, Maltose, Sucrose c. Its glycosidic linkage is a “head-to-head” linkage. Maltose, Cellobiose, Lactose d. It is not a reducing sugar Sucrose 2. What monosaccharides are produced from the hydrolysis of the following disaccharides? a. Sucrose Two D-glucose b. Maltose Two D-glucose c. Lactose Galactose, Glucose d. Cellobiose Glucose, Fructose 3. What type of glycosidic linkage [α (→ 4) etc.] is present in each of the following disaccharides? a. (1→ 6) b. (1 → 4) c. (1 → 4) d. (1 → 4) 4. For each of the structures in Problem 3, specify whether the disaccharide is in an α configuration or a β configuration, or neither. a. β(1→6) b. β(1 → 4) c. α(1→ 4)

d. α(1 → 4) 5. Identify each of the structures in Problem 3 as a reducing sugar or a nonreducing sugar. a. Reducing Sugar b. Reducing sugar c. Reducing sugar d. Reducing sigar

TOPIC 13 ENHANCEMENT ACTIVITY/OUTPUT: Perform as indicated. 1. What is the difference, if any, between • a polysaccharide and a glycan? A polysaccharide is a polymer that contains many monosaccharide units bonded to each other by glycosidic linkages. Glycan is an alternate name for a polysaccharide. • a homopolysaccharide and a heteropolysaccharide? A homopolysaccharide is a polysaccharide in which only one type of monosaccharide monomer is present. A heteropolysaccharide is a polysaccharide in which more than one (usually two) type of monosaccharide monomer is present.

2. What is the range for the polymer chain length in a polysaccharide? Polysaccharide chain length can vary from less than a hundred monomer units to up to a million monomer units.

3. Indicate whether or not each of the following is a correct characterization for the amylose form of starch. a. It is a homopolysaccharide. It is a correct characterization of amylose b. It contains two different types of monosaccharide molecules. It is not a correct characterization of amylose c. It is a branched-chain glucose polymer. It is not a correct characterization of amylose d. All glycosidic linkages present are α(1→ 4) It is a correct characterization of amylose

4. Indicate whether or not each of the following is a correct characterization for glycogen.

a. It is a homopolysaccharide. It is a correct characterization of glycogen b. It contains two different types of monosaccharide molecules. It is not a correct characterization of glycogen c. It is a branched-chain glucose polymer. It is a correct characterization of glycogen

d. All glycosidic linkages present are α(1→ 4). It is not a correct characterization of glycogen

5. What is the difference, if any, between the amylose and amylopectin forms of starch in terms of the following? a. Relative abundance Amylose, a straight-chain glucose polymer, usually accounts for 15%–20% of the starch; amylopectin, a branched glucose polymer, accounts for the remaining 80%– 85% of the starch. b. Type of glycosidic linkages present In amylose, they are all (1 → 4); in amylopectin, both (1 → 4) and (1 → 6) linkages are present. b. Length of polymer chain The number of glucose units present in an amylose chain depends on the source of the starch; 300– 500 monomer units are usually present. Up to 100,000 glucose units may be present in an amylopectin polymer chain. c. Type of monosaccharide monomers present Amylose and amylopectin have the same monosaccharide monomers present which is glucose. So, there is no difference between amylose and amylopectin.

TOPIC 14 ENHANCEMENT ACTIVITY/OUTPUT: Perform as indicated. 1. Indicate whether or not each of the following is a correct characterization for cellulose. a. It is an unbranched glucose polymer. It is a correct characterization. b. Its glycosidic linkages are of the same type as those in starch. It is not a correct characterization.

c. It is a source of nutrition for humans. It is not a correct characterization. d. One of its biochemical functions is that of dietary fiber. e. It is a correct characterization.

2. Indicate whether or not each of the following is a correct characterization for chitin. a. It is an unbranched polymer. It is a correct characterization. b. Two different types of monomers are present. It is not a correct characterization. c. Glycosidic linkages present are the same as those in cellulose. It is a correct characterization. d. The monomers present are glucose derivatives rather than glucose itself. It is a correct characterization.

3. Indicate whether or not each of the following characterizations applies to (1) both cellulose and chitin, (2) to cellulose only, (3) to chitin only, or (4) to neither cellulose nor chitin. a. Storage polysaccharide Neither cellulose nor chitin b. Monomers are glucose units Cellulose only c. Glycosidic linkages are all α(1→ 4) Neither cellulose nor chitin d. An unbranched polymer Both cellulose and chitin e. Structural polysaccharide Both cellulose and chitin f.

Monomers are glucose derivatives Chitin only

g. Homopolysaccharide Both cellulose and chitin

4. Indicate whether or not each of the following is a correct characterization for hyaluronic acid. a. Heteropolysaccharide It is a correct characterization. b. Monomer repeating units are a disaccharide It is not a correct characterization. c. Two types of glycosidic linkages are present It is a correct characterization. d. A very small polysaccharide It is not a correct characterization.

5. Indicate whether or not each of the following is a correct characterization for heparin. a. Heteropolysaccharide It is a correct characterization. b. Monomer repeating units are a disaccharide It is a correct characterization. c. Two types of glycosidic linkages are present It is not a correct characterization. d. A very small polysaccharide It is a correct characterization.

6. What is the biological function for heparin? for hyaluronic acid? The best known of heparin’s biochemical functions is that of an anticoagulant; it helps prevent blood clots. It binds strongly to a protein involved in terminating the process of blood clotting, thus inhibiting blood clotting. Highly viscous hyaluronic acid solutions serve as lubricants in the fluid of joints and they are also associated with the jelly-like consistency of the vitreous humor of the eye.

TOPIC 15 ENHANCEMENT ACTIVITY/OUTPUT: Perform as indicated. 1. Differentiate glycolipid and glycoprotein in terms of structure. A glycolipid is a lipid molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it. Similarly, a glycoprotein is a protein molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it.

2. Describe the general features of the cell recognition process in which glycoproteins and glycolipids participate. The lipid or protein part of the glycolipid or glycoprotein is incorporated into the cell membrane structure and the carbohydrate (oligosaccharide) part functions as a marker on the outer cell membrane surface. In the human reproductive process, fertilization involves a binding interaction between oligosaccharide markers on the outer membrane surface of an ovulated egg and protein receptor sites on a sperm cell membrane. This binding process is followed by release of enzymes by the sperm cell which dissolve the egg cell membrane allowing for entry of the sperm and the ensuing egg–sperm fertilization process. The oligosaccharide markers on cell surfaces that are the basis for blood types. 3. In a dietary context, what is the difference between: a. simple carbohydrate and a complex carbohydrate? A simple carbohydrate is a dietary monosaccharide or disaccharide. Simple carbohydrates are usually sweet to the taste and are commonly referred to as sugars. A complex carbohydrate is a dietary polysaccharide. b. a natural sugar and a refined sugar? A natural sugar is a sugar naturally present in whole foods. Milk and fresh fruit are two important sources of natural sugars. A refined sugar is a sugar that has been separated from its plant source. 4. In a dietary context, what: a. are empty calories? Refined sugars are often said to provide empty calories because they provide energy but few other nutrients b. is the glycemic effect? The term glycemic effect refers to how quickly carbohydrates are digested (broken down into glucose), how high blood glucose levels rise, and how quickly blood glucose levels return to normal. A measurement system called the glycemic index (GI) has been developed for rating foods in terms of their glycemic effect...