Question 1

What is the biological advantage to an organism that stores its carbohydrate reserves as starch or glycogen rather than as an equivalent amount of free glucose?

Accepted Answer

The polymers are essentially insoluble and contribute little to the osmolarity of the cell,thereby avoiding the influx of water that would occur with the glucose in solution.They also make the uptake of glucose energetically more feasible than it would be with free glucose in the cell.

Question 2

Describe the structure of a proteoglycan aggregate such as is found in the extracellular matrix.

Accepted Answer

A proteoglycan aggregate is a supramolecular assembly of proteoglycan monomers.Each monomer consists of a core protein with multiple,covalently linked polysaccharide chains.Hundreds of these monomers can bind noncovalently to a single extended molecule of hyaluronic acid to form large structures.

Question 3

In measuring long-term glucose levels in the bloodstream,glycated hemoglobin must be separated from unmodified hemoglobin to determine the percentage of glycated hemoglobin.Suggest a simple chromatographic method by which this separation can be performed.

Accepted Answer

Free hemoglobin has more positively charged residues (both lysine side chains and free amino ends)than glycated hemoglobin,where these amines have been converted to uncharged Schiff bases (see Box 7-1).Therefore,free hemoglobin is more positively charged than glycated hemoglobin and ion exchange chromatography could be used.(Whether one uses anion or cation exchange chromatography depends on the pI of hemoglobin (6.9)and the pH of the buffer;see Chapter 3. )

Question 4

Which of the following techniques is not commonly used to study oligosaccharide structures?

Accepted Answer

A) X-ray crystallography 
B) Matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS) 
C) Nuclear magnetic resonance (NMR) 
D) Complete chemical synthesis 
E) Oligosaccharide microarrays 
A) X-ray crystallography 
B) Matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS) 
C) Nuclear magnetic resonance (NMR) 
D) Complete chemical synthesis 
E) Oligosaccharide microarrays

Question 5

What are lectins? What are some biological processes that involve lectins?

Accepted Answer

Lectins are proteins that bind to specif

Question 6

The basic structure of a proteoglycan consists of a core protein and a:

Accepted Answer

A) glycolipid. 
B) glycosaminoglycan. 
C) lectin. 
D) lipopolysaccharide. 
E) peptidoglycan. 
A) glycolipid. 
B) glycosaminoglycan. 
C) lectin. 
D) lipopolysaccharide. 
E) peptidoglycan.

Question 7

Which of the following statements concerning sialic acid residues on glycoproteins is true?

Accepted Answer

A) Sialic residues on erythrocytes are recognized by lectins,leading to removal of the erythrocytes. 
B) Sialic residues on ceruloplasmin are recognized by lectins,leading to removal of ceruloplasmin. 
C) Sialic residues are removed by neuraminidases. 
D) The anti-viral drug oseltamavir accelerates the removal of sialic acid residues. 
E) Both A and B above 
A) Sialic residues on erythrocytes are recognized by lectins,leading to removal of the erythrocytes. 
B) Sialic residues on ceruloplasmin are recognized by lectins,leading to removal of ceruloplasmin. 
C) Sialic residues are removed by neuraminidases. 
D) The anti-viral drug oseltamavir accelerates the removal of sialic acid residues. 
E) Both A and B above

Question 8

When forming the disaccharide maltose from two glucose monosaccharides:

Accepted Answer

A) water is eliminated. 
B) a hemiacetal is converted to an acetal. 
C) the resulting dissacharide is no longer a reducing sugar. 
D) Both A and B 
E) A,B,and C above 
A) water is eliminated. 
B) a hemiacetal is converted to an acetal. 
C) the resulting dissacharide is no longer a reducing sugar. 
D) Both A and B 
E) A,B,and C above

Question 9

(a)Define "reducing sugar." 
(b)Show the reaction product of glucose after it is used as a reducing sugar.
(c)Explain why fructose is also considered a reducing sugar.(Hint: It must first undergo a chemical conversion. )
(d)Sucrose is a disaccharide composed of glucose and fructose
(Glc($\beta$1 $\rightarrow$ 2)Fru).Explain why sucrose is not a reducing sugar,even though both glucose and fructose are.

Accepted Answer

(a)A reducing sugar is one with a free c

Question 10

d-Glucose is called a reducing sugar because it undergoes an oxidation-reduction reaction at the anomeric carbon.One of the products of this reaction is:

Accepted Answer

A) d-galactose. 
B) d-gluconate. 
C) d-glucuronate. 
D) d-ribose. 
E) muramic acid. 
A) d-galactose. 
B) d-gluconate. 
C) d-glucuronate. 
D) d-ribose. 
E) muramic acid.

Question 11

Which of the following monosaccharides is not an aldose?

Accepted Answer

A) Erythrose 
B) Fructose 
C) Glucose 
D) Glyceraldehyde 
E) Ribose 
A) Erythrose 
B) Fructose 
C) Glucose 
D) Glyceraldehyde 
E) Ribose

Question 12

Starch and glycogen are both polymers of:

Accepted Answer

A) fructose. 
B) glucose1-phosphate. 
C) sucrose. 
D) ($\alpha$-d-glucose.) 
E) ($\beta$-d-glucose.) 
A) fructose. 
B) glucose1-phosphate. 
C) sucrose. 
D) ($\alpha$-d-glucose.) 
E) ($\beta$-d-glucose.)

Question 13

Which of the following statements about heparan sulfate is not true?

Accepted Answer

A) Sulfation of heparan sulfate to form NS domains is important for its role as an anti-coagulant. 
B) Heparan sulfate can promote protein-protein interactions via the NS domains. 
C) The secondary structure of heparan sulfate is completely random. 
D) The NA domains of heparan sulfate contain no sulfation. 
E) The core repeating structure of heparan sulfate is made up of alternating GlcNAc and GlcA. 
A) Sulfation of heparan sulfate to form NS domains is important for its role as an anti-coagulant. 
B) Heparan sulfate can promote protein-protein interactions via the NS domains. 
C) The secondary structure of heparan sulfate is completely random. 
D) The NA domains of heparan sulfate contain no sulfation. 
E) The core repeating structure of heparan sulfate is made up of alternating GlcNAc and GlcA.

Question 14

Which of following is an anomeric pair?

Accepted Answer

A) d-glucose and d-fructose 
B) d-glucose and l-fructose 
C) d-glucose and l-glucose 
D) ($\alpha$-d-glucose and $\beta$-d-glucose) 
E) ($\alpha$-d-glucose and $\beta$-l-glucose) 
A) d-glucose and d-fructose 
B) d-glucose and l-fructose 
C) d-glucose and l-glucose 
D) ($\alpha$-d-glucose and $\beta$-d-glucose) 
E) ($\alpha$-d-glucose and $\beta$-l-glucose)

Question 15

Which of the following is a heteropolysaccharide?

Accepted Answer

A) Cellulose 
B) Chitin 
C) Glycogen 
D) Hyaluronate 
E) Starch 
A) Cellulose 
B) Chitin 
C) Glycogen 
D) Hyaluronate 
E) Starch

Question 16

Which of the following is not a reducing sugar?

Accepted Answer

A) Fructose 
B) Glucose 
C) Glyceraldehyde 
D) Ribose 
E) Sucrose 
A) Fructose 
B) Glucose 
C) Glyceraldehyde 
D) Ribose 
E) Sucrose

Question 17

In the following structure:   (a)How many of the monosaccharide units are furanoses and how may are pyranoses? 
(b)What is the linkage between the two monosaccharide units? 
(c)Is this a reducing sugar?

Accepted Answer

(a)2 pyranoses; 
(b)@#LAT-DLM&1 @#LAT-DLM& 4; 
(c)

Question 18

Sketch the principal components of a typical proteoglycan,showing their relationships and connections to one another.

Accepted Answer

A typical proteoglycan consists of a cor

Question 19

When two carbohydrates are epimers:

Accepted Answer

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 carbon. 
D) they differ only in the configuration around one carbon atom. 
E) they rotate plane-polarized light in the same direction. 
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 carbon. 
D) they differ only in the configuration around one carbon atom. 
E) they rotate plane-polarized light in the same direction.

Question 20

In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues:

Accepted Answer

A) asparagine,serine,or threonine. 
B) aspartate or glutamate. 
C) glutamine or arginine. 
D) glycine,alanine,or aspartate. 
E) tryptophan,aspartate,or cysteine. 
A) asparagine,serine,or threonine. 
B) aspartate or glutamate. 
C) glutamine or arginine. 
D) glycine,alanine,or aspartate. 
E) tryptophan,aspartate,or cysteine.

Exam 7: Carbohydrates and Glycobiology

What is the biological advantage to an organism that stores its carbohydrate reserves as starch or glycogen rather than as an equivalent amount of free glucose?

Describe the structure of a proteoglycan aggregate such as is found in the extracellular matrix.

In measuring long-term glucose levels in the bloodstream,glycated hemoglobin must be separated from unmodified hemoglobin to determine the percentage of glycated hemoglobin.Suggest a simple chromatographic method by which this separation can be performed.

Which of the following techniques is not commonly used to study oligosaccharide structures?

What are lectins? What are some biological processes that involve lectins?

The basic structure of a proteoglycan consists of a core protein and a:

Which of the following statements concerning sialic acid residues on glycoproteins is true?

When forming the disaccharide maltose from two glucose monosaccharides:

d-Glucose is called a reducing sugar because it undergoes an oxidation-reduction reaction at the anomeric carbon.One of the products of this reaction is:

Which of the following monosaccharides is not an aldose?

Starch and glycogen are both polymers of:

Which of the following statements about heparan sulfate is not true?

Which of following is an anomeric pair?

Which of the following is a heteropolysaccharide?

Which of the following is not a reducing sugar?

In the following structure: (a)How many of the monosaccharide units are furanoses and how may are pyranoses? (b)What is the linkage between the two monosaccharide units? (c)Is this a reducing sugar?

Sketch the principal components of a typical proteoglycan,showing their relationships and connections to one another.

When two carbohydrates are epimers:

In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues:

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

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