CHE XXXXXXXXXXManual 3E.pdf Copyright © 2014 Pearson Education, Inc. 331 Pre-Lab Study Questions 29 1. What are some sources of carbohydrates in your diet? 2. What does the D in D-glucose mean? 3....

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CHE 121-122 Manual 3E.pdf Copyright © 2014 Pearson Education, Inc. 331 Pre-Lab Study Questions 29 1. What are some sources of carbohydrates in your diet? 2. What does the D in D-glucose mean? 3. What is the bond that links monosaccharides in di- and polysaccharides? 4. Draw the Haworth structure of each of the following: a. -D-galactose. b. -lactose Date Name Section Team Instructor Copyright © 2014 Pearson Education, Inc. 333 REPORT SHEET Types of Carbohydrates LAB 29 A. Monosaccharides 1. L-Glyceraldehyde D-Glyceraldehyde 2. D-Glucose D-Galactose D-Fructose 3. -D-Glucose -D-Glucose Date Name Section Team Instructor 334 Laboratory Manual for General, Organic, and Biological Chemistry 4. -D-Galactose -D-Fructose Questions and Problems Q1 Describe how the structure of D-glucose compares to the structure of D-galactose. B. Disaccharides 1. -maltose 2. Equation for the hydrolysis of -maltose 3. Equation for the formation of -lactose 4. Sucrose Types of Carbohydrates 335 Questions and Problems Q2 What is the type of glycosidic bond in maltose? Q3 Why does maltose have both and forms (anomers)? Explain. C. Polysaccharides 1. Amylose What is the difference in the structure of amylopectin and amylose? 2. Cellulose 336 Laboratory Manual for General, Organic, and Biological Chemistry Questions and Problems Q4 What is the monosaccharide that results from the complete hydrolysis of amylose? Q5 What is the difference in the structure of amylose and cellulose? CHE 121-122 Manual 3E.pdf Copyright © 2014 Pearson Education, Inc. 323 LABORATORY GOALS tional groups of carbohydrates. LAB INFORMATION Time: 2 h Comments: Tear out the report sheets and place them next to the matching procedures. In the study of carbohydrates, it is helpful to review stereoisomers and the formation of hemiacetals. Related Topics: Carbohydrates, monosaccharides, disaccharides, polysaccharides, hemiacetals, stereoisomers, aldohexoses, ketohexoses, chiral compounds, Fischer projections, Haworth structures CHEMICAL CONCEPTS Carbohydrates in our diet are our major source of energy. Foods high in carbohydrates include potatoes, bread, pasta, and rice. If we take in more carbohydrates than we need for energy, the excess is converted to fat, which can lead to a weight gain. The carbohydrate family can be organized into three classes: monosaccharides, disaccharides, and polysaccharides. Carbohydrates contained in foods such as pasta and bread provide energy for the body. A. Monosaccharides Monosaccharides contain C, H, and O in units of 2 n(CH O) . Most common monosaccharides have 6 carbon atoms (hexoses) with a general formula of 6 12 6C H O . They contain many hydroxyl groups ( OH) along with a carbonyl group. The aldoses are monosaccharides with an aldehyde group, and ketoses contain a ketone group. Types of Carbohydrates 29 324 Laboratory Manual for General, Organic, and Biological Chemistry Monosaccharides Sources Glucose 6 12 6C H O Fruit juices, honey, corn syrup Galactose 6 12 6C H O Lactose hydrolysis Fructose 6 12 6C H O Fruit juices, honey, sucrose hydrolysis The letters D and L refer to the orientation of the hydroxyl ( OH) group on the carbon that is one above the bottom carbon. In the isomers of glyceraldehyde, the position of the OH is on the right in the D-isomer and on the left in the L-isomer. The hexoses glucose, galactose, and fructose are the most important monosaccharides. The most common hexose, D-glucose, 6 12 6C H O , also known as dextrose, is found naturally in fruits, vegetables, corn syrup, and honey; it is also the form of glucose in circulating blood, known as blood sugar. D-glucose is a building block of the disaccharides sucrose, lactose, and maltose, and polysaccharides such as amylose, cellulose, and glycogen. Galactose, 6 12 6C H O , is an aldohexose that is obtained from the disaccharide lactose, which is found in milk and milk products. Galactose is important in the cellular membranes of the brain and nervous system. The only difference in D-glucose and D-galactose is the arrangement of the OH group on carbon 4. In contrast to glucose and galactose, fructose, 6 12 6C H O , is a ketohexose. The structure of fructose differs from glucose at carbons 1 and 2 by the location of the carbonyl group. Fructose is the sweetest of the carbohydrates; it is almost twice as sweet as sucrose (table sugar). Haworth Structures Most of the time glucose exists in a ring structure, which forms when the OH on carbon 5 bonds to carbon 1 in the carbonyl group. In the Haworth structure, the new hydroxyl group may be drawn below carbon 1 (the form or anomer) or above carbon 1 (the form or anomer). Types of Carbohydrates 325 B. Disaccharides A disaccharide contains two monosaccharides bonded together. Some common disaccharides include maltose, sucrose (table sugar), and lactose (milk sugar). Disaccharides Sources Monosaccharides Maltose Germinating grains, starch hydrolysis Glucose glucose Lactose Milk, yogurt, ice cream Glucose galactose Sucrose Sugar cane, sugar beets Glucose fructose In a disaccharide, two monosaccharides form a glycosidic bond with the loss of water. For example, in maltose, two glucose units are linked by an -1,4-glycosidic bond. Lactose, milk sugar, is a disaccharide found in milk and milk products. The bond between the monosac- charides in lactose is a -1,4-glycosidic bond because it is the OH group of a form of galactose that forms a bond with the OH group on carbon 4 of glucose. Lactose is a reducing sugar because the bond at carbon 1 can open to give an aldehyde that can reduce other substances. 326 Laboratory Manual for General, Organic, and Biological Chemistry -Lactose, a disaccharide found in milk and milk products, contains -D-galactose and -D-glucose. C. Polysaccharides Polysaccharides are long-chain polymers that contain many thousands of monosaccharides (usually glucose units) joined together by glycosidic bonds. Three important polysaccharides are starch, cellulose, and glycogen. They all contain glucose units, but differ in the type of glycosidic bonds and the amount of branching in the polymer. Polysaccharides Found in Monosaccharides Starch (amylose, amylopectin) Rice, wheat, grains, cereals Glucose Glycogen Muscle, liver Glucose Cellulose Wood, plants, paper, cotton Glucose Starch is an insoluble storage form of glucose found in rice, wheat, potatoes, beans, and cereals. Starch is composed of two kinds of polysaccharides, amylose and amylopectin. Amylose, which makes up about 20% of starch, consists of -D-glucose molecules connected by -1,4-glycosidic bonds in a continuous chain. A typical polymer of amylose may contain from 250 to 4000 glucose units. Amylopectin is a branched-chain polysaccharide that makes up as much as 80% of starch. In amylopectin, -1,4-glycosidic bonds connect most of the glucose molecules. However, at about every 25 glucose units, there are branches of glucose molecules attached by -1,6-glycosidic bonds between carbon 1 of the branch and carbon 6 in the main chain. Glycogen is similar to amylopectin but it is even more highly branched, with -1,6-glycosidic bonds about every 10 to 15 glucose units. Types of Carbohydrates 327 Cellulose is the major structural material of wood and plants. Cotton is almost pure cellulose. In cellulose, glucose molecules form a long unbranched chain similar to amylose except that -1,4-glycosidic bonds connect the glucose molecules. The isomers are aligned in parallel rows that are held in place by hydrogen bonds between the rows. This gives a rigid structure for cell walls in wood and fiber and makes cellulose more resistant to hydrolysis. 328 Laboratory Manual for General, Organic, and Biological Chemistry Types of Carbohydrates 329 EXPERIMENTAL PROCEDURES GOGGLES REQUIRED! A. Monosaccharides Materials: Organic model kits or prepared models 1. Make or observe models of L-glyceraldehyde and D-glyceraldehyde. Draw their Fischer projections. 2. Draw the Fischer projection for D-glucose, D-galactose, and D-fructose. 3. Draw the Haworth (cyclic) structures for the and forms (anomers) for D-glucose. 4. Draw the Haworth (cyclic) structures for the forms (anomers) of D-galactose and D-fructose. B. Disaccharides 1. Using Haworth structures, draw the structure for -maltose. 2. Using Haworth structures, write an equation for the hydrolysis of -maltose by adding 2H O to the glycosidic bond. 3. Using Haworth structures, write an equation for the formation of -lactose from -D-galactose and -D-glucose. 4. Draw the Haworth structure of sucrose and circle the glycosidic bond. C. Polysaccharides 1. Using Haworth structures, draw a portion of amylose consisting of four units of -D-glucose. Indicate the glycosidic bonds. 2. Using Haworth structures, draw a portion of cellulose consisting of four units of -D-glucose. Indicate the glycosidic bonds.
Answered Same DayJun 23, 2021

Answer To: CHE XXXXXXXXXXManual 3E.pdf Copyright © 2014 Pearson Education, Inc. 331 Pre-Lab Study Questions 29...

Sumita Mitra answered on Jun 24 2021
138 Votes
CHE 121-122 Manual 3E.pdf
Date     Name         Section     Team         Instructor               
Pre-Lab Study Questions    29
1. What are some sources of carbohydrates in your diet?
Ans
: The sources of carbohydrates in our diet includes whole grains, starchy vegetables and fruits like apple, oranges, sweet potato, and also from food like beans, green peas, potatoes, corn, yam, and also from sugary foods and beverages.
2. What does the D in D-glucose mean?
Ans: D stands for dextrorotatory in D glucose chiral carbon configuration which is farthest from the aldehyde or keto group.
3. What is the bond that links monosaccharides in di- and polysaccharides?
Ans: A glycosidic bond is a type of bond that joins sugar molecules to each other and joins monosaccharides in di- and polysaccharides
4. Draw the Haworth structure of each of the following:
a. -D-galactose.
b. -lactose
Copyright © 2014 Pearson Education, Inc.    331
Date     Name         Section     Team         Instructor               
REPORT SHEET
Types of Carbohydrates
LAB
29
A. Monosaccharides
(
L
-Glyceraldehyde
D
-Glyceraldehyde
This is a triose monosaccharides and is the simplest one.
It is a
sweet
, colorless, crystalline solid
which is an
intermediate compound in carbohydrate metabolism.
It is the

D-enantiomer of glyceraldehyde
.
It is an enantiomer of a L-glyceraldehyde.
It plays a role in human metabolism.
)1.
(
D
-Glucose
D
-Galactose
D
-Fructose
D-glucose is the
enantiomer of the L-glucose
.
This is commonly called as
dextrose.
This compound is the
most extensively important aldohexose in living organisms
D-Galactose is an

epimer of...
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