Biochem II Exam I

Why is chitin a biologically important polysaccharide?Choose one or more: A. It is a structural component of insect exoskeletons. B. It is a structural component of fungal cell walls. C. It is a structural component of plant cell walls. D. It is a structural component of specialized mammalian cells.

It is a structural component of insect exoskeletons. It is a structural component of fungal cell walls.

Categorize A, B C as aldose, ketose or neither A aldose, B ketose; C neither A ketose, B aldose, C neither A neither, B aldose, C ketose A aldose, B neither, C ketose

A ketose, B aldose, C neither

In nature, glucose isChoose one: A. typically found in its linear form in solution. B. known as gluocopyranose when in its cyclic form. C. typically found as the L isomer. D. a ketose monosaccharide.

B. known as gluocopyranose when in its cyclic form.

Some types of wheat have been genetically manipulated to change the starch biosynthesis pathway. As a result, the modified wheat synthesizes more amylose than the unmodified wheat. Amylose is known as a resistant starch, meaning it resists digestion in the stomach and small intestine. Resistant starch is thought to be beneficial to the digestive system, in the same way that dietary fiber is beneficial. Why is amylose a resistant starch, whereas amylopectin is not? A. Amylose contains only α-1,4 glycosidic bonds, whereas amylopectin contains both α-1,4 and α-1,6 glycosidic bonds. B. Bacteria in the gut ferment amylose, which prevents digestion. C. Amylose contains more glucose residues within the structure than amylopectin. D. Humans do not express α-amylase and therefore cannot digest amylose.

Amylose contains only α-1,4 glycosidic bonds, whereas amylopectin contains both α-1,4 and α-1,6 glycosidic bonds.

Which of the following pairs are epimers?Choose one or more: A. mannose and galactose B. glucose and fructose C. glucose and mannose D. glucose and galactose

C. glucose and mannose D. glucose and galactose

N-linked glycoproteins have their glycans attached to which amino acid?Choose one: A. Lys B. Ser C. Thr D. Asn

Asn

The figure below shows two disaccharides commonly found in nature. Which end is responsible for a positive result in Benedict's test?

B

Based on the structures given: D-galactose is a ____ epimer of D-glucose A. C2 B. C3 C. C4 D. C5 E. C6

C4

Identify the unique characteristics of cellulose and chitin as well as the characteristics common to both. contains glucose, , component of invertebrate exoskeleton, monosaccharides linked by B 1->4 glycosidic bond, homopolymer, contains N-acetylglucosamine, component of plant cell wall, H bonds between polysaccharide strands that increase strength and rigidity

Cellulose: contains glucose, component of plant cell wall Chitin: contains N-acetylglucosamine, component of invertebrate exoskeleton Both: H bonds between polysaccharide strands that increase strength and rigidity, homopolymer, monosaccharides linked by B 1->4 glycosidic bond

Which of the following relationships is correctly defined?Choose one: A. D-Ribose and D-Xylose are isomers B. D-Glucose and D-Mannose are anomers C. D-Glucose and L-Glucose are anomers D. D-Ribose and D-Xylose are epimers

D-Ribose and D-Xylose are epimers

D-Glycose is called a reducing sugar because it undergoes an oxidation-reduction reaction at the anomeric carbon. One of the products of this reaction is: 1. D-galactose 2. D-gluconate 3. D-glucuronate 4. D-ribose 5. Muramic acid

D-gluconate

4. When two carbohydrates are epimers: A. one is a pyranose, the other a furanose B. one is an aldose, the other a ketose C. they differ in length by one chiral carbon D. they differ in the configuration around one chiral carbon atom E they rotate plane-polarized light in the same direction

D. they differ in the configuration around one chiral carbon atom

Which of the following statements correctly describe the properties of glucose and fructose?Choose one or more: A. Glucose and fructose are both hexose sugars. B. Glucose can form furanose and pyranose ring structures, while fructose can only form a furanose ring. C. Glucose is found in at least three common disaccharides found in nature, while fructose is a component of only one. D. Glucose and fructose are both reducing sugars.

Glucose and fructose are both hexose sugars. Glucose can form furanose and pyranose ring structures, while fructose can only form a furanose ring. Glucose is found in at least three common disaccharides found in nature, while fructose is a component of only one.

Which of the following is an example of a polysaccharide? a) Galactose b) Raffinose c) Glycogen d) Maltose

Glycogen

Which of the following is the MOST efficient storage form of glucose as an energy source? a) Glycogen b) Amylopectin c) Cellulose d) Amylose

Glycogen

Which of the following is NOT a type of glycoconjugate?Choose one: A. Proteoglycan B. Heparan sulfate C. Glycoprotein D. Glycolipid

Heparan sulfate

The human gut microbiome is a collection of microbes that are necessary for proper function of the digestive system and that contribute to the overall health of the individual. Infants are colonized with these microbes at birth and their nutrition in the early days of life is important for supporting growth of these microbes. Milk sugars are important in development of the microbiome. Which of the following best explains how both lacto-N-tetraose and lacto-N-fucopentaose could contribute to proper development of an infant's microbiome? choose one or more: A. Lacto-N-tetraose prevents pathogenic bacteria from hydrolyzing and metabolizing carbohydrates found in the intestine. B. Lacto-N-fucopentaose is digested by pathogenic bacteria and, in the process, destroys these types of bacteria. C. Lacto-N-fucopentaose binds to surface receptors on pathogenic bacteria and prevents them from entering epithelial cells in the intestine. D. Lacto-N-tetraose is a food source for bacteria that aid in digestion of this and other oligosaccharides.

Lacto-N-fucopentaose binds to surface receptors on pathogenic bacteria and prevents them from entering epithelial cells in the intestine. AND Lacto-N-tetraose is a food source for bacteria that aid in digestion of this and other oligosaccharides.

Which of the following is an example of a disaccharide?Choose one: A. Lactose B. Galactose C. Glucose D. Raffinose

Lactose

Galactose is a component in many types of carbohydrates. Rank these galactose-containing carbohydrates in order of polymer length. Lacto-N-tetraose Raffinose Lactose Keratan Sulfate Verbascose

Lactose Raffinose Lacto-N-tetraose Verbascose Keratan Sulfate

The compound shown is an aldose A. True B. False

false

Which of the following is an example of a reducing sugar?

a and d

Identify these carbohydrates as simple sugars or polysaccharides. Glucose, Chitin, Lactose, Starch, Glycogen, Raffinose

Simple Sugars: Glucose, Lactose, Raffinose polysaccharides: Chitin, Starch, Glycogen

Which of the following explains why humans and other nonruminating animals cannot digest raffinose series monosaccharides? A. These oligosaccharides are degraded by bacteria in the lower intestine before they can be digested. B. These oligosaccharides are too long to be substrates for the digestive enzymes of humans and other nonruminating animals. C. These oligosaccharides contain monosaccharides that are not substrates for metabolic reactions in humans and nonruminating organisms. D. The galactose residues in these oligosaccharides are joined by an α-1,6 glycosidic bond.

The galactose residues in these oligosaccharides are joined by an α-1,6 glycosidic bond.

Beano is a dietary supplement that allows humans to digest oligosaccharides such as stachyose by supplying the enzyme necessary to hydrolyze the α-1,6 glycosidic bond in these carbohydrates. However, other dietary carbohydrates such as amylopectin contain α-1,6 glycosidic bonds and these polysaccharides are easily digested by humans. How is this possible?Choose one: A. The α-1,6 glycosidic bond in amylopectin does not require an enzyme for hydrolysis. B. Bacteria in the gut provide the glycosidase necessary to digest amylopectin, but there are no bacteria that express the correct enzyme for stachyose. C. The residues connected by the α-1,6 glycosidic bond are different in stachyose and amylopectin. D. Amylopectin is absorbed by a different part of the intestine than stachyose.

The residues connected by the α-1,6 glycosidic bond are different in stachyose and amylopectin.

What is the correct name for the structure shown below? A. B-D-galactopyranose B. B-D-glucopyranose C. a-D-galactopyranose D. a-D-glucopyranose

a-D-galactopyranose

Which of the following pairs is interconverted in the process of mutarotation? A. D-glucose and D-fructose B. D-glucose and D-galactose C. D-glucose and D-glucosamine D. D-glucose and L-glucose E. alpha-D-glucose and beta-D-glucose

alpha-D-glucose and beta-D-glucose

Which of the following glycoconjugates is predominantly protein?Choose one: A. Antibodies B. Aggrecan C. Perlecan D. Peptidoglycan

antibodies

Why is chitin a biologically important polysaccharide? a) It is a structural component of plant cell walls b) It is a structural component of fungal cell walls c) It is a structural component of specialized mammalian cells d) It is a structural component of insect exoskeletons.

b) It is a structural component of fungal cell walls d) It is a structural component of insect exoskeletons.

Determine relationship between 1, 2 and 3 A. 1 and 3 are epimers B. 2 and 3 are anomers C. Both are true

both are true

The structure of D-arabinose is shown below as a Fischer projection. Identify the correct structure of L-arabinose.

c

Which of the following are modified monosaccharides frequently found in glycoconjugates? (picture)

c and d

A common feature between cellulose and chitin is that they both Choose one: A. are made up of N-acetylglucosamine. B. are found in the cell walls of plants. C. contain β-1,4-glycosidic bonds. D. are found in invertebrate exoskeletons.

contain β-1,4-glycosidic bonds.

Glucose and galactose are components of many disaccharides, oliogsaccharides, and polysaccharides. Sort these common carbohydrates to indicate if they contain glucose, galactose, or both. Lacto-N-tetraose, starch, lactose, maltose, sucrose, raffinose

gluocose: maltose, starch, sucrose galactose: Lacto-N-teraose both: raffinose, lactose,

Which of the following is an example of a polysaccharide?Choose one: A. Maltose B. Raffinose C. Galactose D. Glycogen

glycogen

Which of the following is the MOST efficient storage form of glucose as an energy source?Choose one: A. Amylose B. Amylopectin C. Glycogen D. Cellulose

glycogen

Chondroitin sulfate, heparan sulfate, and keratan sulfate are examples of __________ composed of repeating disaccharide units. The most highly sulfonated of these is ____________ .

glycosaminoglycans, heparin sulfate

Linear hexosamine polysaccharides such as heparan sulfate, keratan sulfate, and chondroitin sulfate are classified as______. These particular hexosamines are distinct from other polysaccharides such as chitin due to their ability to form ________ through covalent attachment to proteins.

glycosoaminoglycans, proteoglycans

A common feature between amylose and amylopectin is that they both Choose one: A. are only approximately 100 units long. B. only contain α-1,4 glycosidic linkages. C. have a single accessible end for glucose removal. D. have linear regions capable of forming left-handed helix.

have linear regions capable of forming left-handed helix.

Glucose and galactose are components of many disaccharides, oliogsaccharides, and polysaccharides. Sort these common carbohydrates to indicate if they contain glucose, galactose, or both: maltose, starch, Lacto-N-tetraose, raffinose, lactose, sucrose,

maltose, starch, sucrose Lacto-N-tetraose raffinose, lactose

Which of the following is an example of a monosaccharide?Choose one: A. Mannose B. Sucrose C. Raffinose D. Maltose

mannose

What type of glycan is shown in the illustration? A. polysaccharide B. disaccharide C. monosaccharide D. oligosaccharide

oligosaccharide

This molecule is a: A. monosaccharide, as it has 1 monosaccharide and no glycosidic bonds B. disaccharide, as it has 2 monosaccharides and 1 glycosidic bond C. oligosaccharide, as it has 3 monosaccharides and 2 glycosidic bonds D. polysaccharide, as it has 3 monosaccharides and 2 glycosidic bonds

oligosaccharide, as it has 3 monosaccharides and 2 glycosidic bonds

What type of glycan is shown in the illustration?Choose one: A. disaccharide B. monosaccharide C. oligosaccharide D. polysaccharide

oligosaccharides

identify these carbohydrates as simple sugars or polysaccharides: glucose, chitin, raffinose, lactose, starch, glycogen

simple sugars: glucose, raffinose, lactose polysaccharides: starch, glycogen, chitin

Which disaccharide found in raffinose, stachyose, and verbascose, shown in the figure below, cannot be digested by humans and other non-ruminating animals? Choose one: A. Cellobiose B. Lactose C. Maltose D. Sucrose

sucrose

Which disaccharide found in raffinose, stachyose, and verbascose, shown in the figure below, cannot be digested by humans and other non-ruminating animals?Choose one: A. Sucrose B. Cellobiose C. Lactose D. Maltose

sucrose

Which of the following is NOT a reducing sugar? 1. Fructose 2. Glucose 3. Glyceraldehyde 4. Ribose 5. Sucrose

sucrose