Question 1

Which statement 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 antiviral drug oseltamavir accelerates the removal of sialic acid residues. 
E)  All of the statements are true. 
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 antiviral drug oseltamavir accelerates the removal of sialic acid residues. 
E)  All of the statements are true. C

Question 2

Enzymatic hydrolysis of a purified polysaccharide with a glycosidase that cleaves specifically usually occurs before analysis by:

Accepted Answer

A)  NMR and mass spectrometry. 
B)  ion-exchange chromatography. 
C)  gel-filtration chromatography. 
D)  lectin-affinity chromatography. 
E)  gas-liquid chromatography. 
A)  NMR and mass spectrometry. 
B)  ion-exchange chromatography. 
C)  gel-filtration chromatography. 
D)  lectin-affinity chromatography. 
E)  gas-liquid chromatography. A

Question 3

How do oligosaccharide portions of glycoproteins change the properties of the proteins?

Accepted Answer

The oligosaccharide portions of glycoproteins, also known as glycans, can significantly alter the properties and functions of the proteins to which they are attached. These changes can be diverse and impact various aspects of protein behavior. Here are some of the ways in which oligosaccharides can modify protein properties:

1. **Solubility and Stability**: Glycosylation often increases the solubility of proteins in aqueous solutions. The hydrophilic nature of sugars can help to prevent protein aggregation and stabilize the protein structure, which is particularly important for proteins that operate in extracellular environments.

2. **Folding and Quality Control**: Glycans play a crucial role in protein folding and are involved in quality control mechanisms within the endoplasmic reticulum (ER). They help in the proper folding of proteins by interacting with chaperones and can signal if a protein is misfolded, targeting it for degradation.

3. **Protein Activity**: The activity of certain enzymes and receptors can be modulated by the presence of glycans. For example, glycosylation can either activate or inhibit enzyme activity, and it can also affect the binding affinity of receptors for their ligands.

4. **Cellular Recognition and Signaling**: Glycoproteins are often involved in cell-cell recognition and signaling processes. The oligosaccharides can serve as specific binding sites for other molecules, such as antibodies, lectins, or other cells, facilitating communication and interaction between cells.

5. **Protection from Proteolysis**: The addition of oligosaccharides can protect proteins from proteolytic enzymes, thereby increasing their half-life in circulation. This is particularly important for therapeutic proteins and hormones.

6. **Immunogenicity**: Glycosylation patterns can affect the immune response to a protein. Certain glycan structures can be recognized by the immune system, leading to an immune reaction. This is a critical consideration in the development of biopharmaceuticals, as non-human glycosylation patterns can trigger an immune response.

7. **Cellular Localization**: Glycans can influence the localization of proteins within the cell or on the cell surface. For example, specific glycosylation patterns are required for proteins to be transported to lysosomes.

8. **Molecular Stability**: Glycosylation can contribute to the thermal and chemical stability of proteins, making them less susceptible to denaturation under stress conditions.

9. **Clearance from the Body**: The structure of glycans can affect the rate at which glycoproteins are cleared from the bloodstream. For instance, certain glycan structures can be recognized by receptors in the liver and lead to the rapid clearance of the glycoprotein.

In summary, the oligosaccharide portions of glycoproteins are critical for a wide range of protein functions and properties. They can influence how proteins fold, how they function, how they interact with other molecules, and how they are recognized by the body. Understanding glycosylation patterns is essential for the study of protein function and the development of therapeutic proteins.

Question 4

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

Accepted Answer

Lectins are a type of protein that can b

Question 5

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 6

High-performance liquid chromatography (HPLC) can be used to determine the:

Accepted Answer

A)  position(s) of glycosidic bonds in a polysaccharide. 
B)  sequence of monosaccharides from a polysaccharide. 
C)  sequence of monosaccharides, as well as position and configuration of glycosidic bonds. 
D)  types and amounts of monosaccharide units in a polysaccharide. 
E)  None of the answers is correct. 
A)  position(s) of glycosidic bonds in a polysaccharide. 
B)  sequence of monosaccharides from a polysaccharide. 
C)  sequence of monosaccharides, as well as position and configuration of glycosidic bonds. 
D)  types and amounts of monosaccharide units in a polysaccharide. 
E)  None of the answers is correct.

Question 7

Which polysaccharide(s) can the enzyme $\alpha$-amylase break?

Accepted Answer

A)  glycogen 
B)  starch 
C)  cellulose 
D)  both glycogen and cellulose 
E)  both glycogen and starch 
A)  glycogen 
B)  starch 
C)  cellulose 
D)  both glycogen and cellulose 
E)  both glycogen and starch

Question 8

Which monosaccharides is NOT a carboxylic acid?

Accepted Answer

A)  6-phospho-gluconate 
B)  gluconate 
C)  glucose 
D)  glucuronate 
E)  muramic acid 
A)  6-phospho-gluconate 
B)  gluconate 
C)  glucose 
D)  glucuronate 
E)  muramic acid

Question 9

Which statement accurately describes the interactions between the molecules thrombin, antithrombin, and heparan sulfate?

Accepted Answer

A)  In the absence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation. 
B)  In the absence of heparan sulfate, antithrombin cannot bind to thrombin, inhibiting blood coagulation. 
C)  In the presence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation. 
D)  In the presence of heparan sulfate, antithrombin cannot bind to thrombin, enabling blood coagulation. 
E)  In the presence of heparan sulfate, antithrombin binds tightly to thrombin, enabling blood coagulation. 
A)  In the absence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation. 
B)  In the absence of heparan sulfate, antithrombin cannot bind to thrombin, inhibiting blood coagulation. 
C)  In the presence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation. 
D)  In the presence of heparan sulfate, antithrombin cannot bind to thrombin, enabling blood coagulation. 
E)  In the presence of heparan sulfate, antithrombin binds tightly to thrombin, enabling blood coagulation.

Question 10

Which polysaccharide is NOT a homopolysaccharide?

Accepted Answer

A)  glycogen 
B)  chitin 
C)  amylose 
D)  glycosaminoglycan 
E)  dextran 
A)  glycogen 
B)  chitin 
C)  amylose 
D)  glycosaminoglycan 
E)  dextran

Question 11

Which description of a ganglioside is MOST accurate?

Accepted Answer

A)  the dominant surface feature of gram-negative bacteria. 
B)  the dominant surface feature of gram-positive bacteria. 
C)  an oligosaccharide chain attached to a newly synthesized protein in the ER 
D)  a membrane lipid in which the polar head group is a complex oligosaccharide containing at least one sialic acid 
E)  a membrane lipid in which the oligosaccharide is attached to a mucin 
A)  the dominant surface feature of gram-negative bacteria. 
B)  the dominant surface feature of gram-positive bacteria. 
C)  an oligosaccharide chain attached to a newly synthesized protein in the ER 
D)  a membrane lipid in which the polar head group is a complex oligosaccharide containing at least one sialic acid 
E)  a membrane lipid in which the oligosaccharide is attached to a mucin

Question 12

In amylose, the most stable structure is a _____, which is stabilized by _____.

Accepted Answer

A)  coiled helix; interchain hydrogen bonds 
B)  coiled helix; interchain covalent branching 
C)  coiled helix; hydrogen bonds to surrounding water molecules 
D)  straight, extended chain; interchain hydrogen bonds 
E)  straight, extended chain; hydrogen bonds to surrounding water molecules 
A)  coiled helix; interchain hydrogen bonds 
B)  coiled helix; interchain covalent branching 
C)  coiled helix; hydrogen bonds to surrounding water molecules 
D)  straight, extended chain; interchain hydrogen bonds 
E)  straight, extended chain; hydrogen bonds to surrounding water molecules

Question 13

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

Accepted Answer

Proteoglycans are large molecules compos

Question 14

The severalfold greater incidence of gastric ulcers in _____ is due in part to a surface lectin in the bacterium Helicobacter pylori.

Accepted Answer

A)  men versus women 
B)  people with a certain blood type 
C)  people of a certain age 
D)  people with autoimmune diseases 
E)  None of the answers is correct. 
A)  men versus women 
B)  people with a certain blood type 
C)  people of a certain age 
D)  people with autoimmune diseases 
E)  None of the answers is correct.

Question 15

Of the 16 possible aldohexoses, 8 are D forms and 8 are L forms. However, most of the hexoses of living organisms are D isomers. Speculate in a few sentences the possible reason for this preference.

Accepted Answer

One possible reason for the preference o

Question 16

The biochemical property of lectins that is the basis for most of their biological effects is their ability to bind to:

Accepted Answer

A)  amphipathic molecules. 
B)  hydrophobic molecules. 
C)  specific lipids. 
D)  specific oligosaccharides. 
E)  specific peptides. 
A)  amphipathic molecules. 
B)  hydrophobic molecules. 
C)  specific lipids. 
D)  specific oligosaccharides. 
E)  specific peptides.

Question 17

Several types of human joint and skeletal defects are a result of a defect in a biosynthetic enzyme responsible for synthesis of:

Accepted Answer

A)  glycosaminoglycans. 
B)  glycoproteins. 
C)  glycolipids. 
D)  lipopolysaccharides. 
E)  glycosphingolipids. 
A)  glycosaminoglycans. 
B)  glycoproteins. 
C)  glycolipids. 
D)  lipopolysaccharides. 
E)  glycosphingolipids.

Question 18

The reference compound for naming D and L isomers of sugars is:

Accepted Answer

A)  fructose. 
B)  glucose. 
C)  glyceraldehyde. 
D)  ribose. 
E)  sucrose. 
A)  fructose. 
B)  glucose. 
C)  glyceraldehyde. 
D)  ribose. 
E)  sucrose.

Question 19

What possible benefits are provided by extended conformation that the heteropolysaccharide glycosaminoglycans assume in solution?

Accepted Answer

A)  The repulsive forces of densely packed negative charges are minimized. 
B)  The hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces. 
C)  The patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands. 
D)  The repulsive forces of densely packed negative charges are minimized, and the hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces. 
E)  The repulsive forces of densely packed negative charges are minimized, and the patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands. 
A)  The repulsive forces of densely packed negative charges are minimized. 
B)  The hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces. 
C)  The patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands. 
D)  The repulsive forces of densely packed negative charges are minimized, and the hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces. 
E)  The repulsive forces of densely packed negative charges are minimized, and the patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands.

Question 20

Which statement about heparan sulfate is NOT true?

Accepted Answer

A)  Sulfation of heparan sulfate to form NS domains is important for its role as an anticoagulant. 
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 anticoagulant. 
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.

Exam 7: Carbohydrates and Glycobiology

Which statement concerning sialic acid residues on glycoproteins is TRUE?

Enzymatic hydrolysis of a purified polysaccharide with a glycosidase that cleaves specifically usually occurs before analysis by:

How do oligosaccharide portions of glycoproteins change the properties of the proteins?

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

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

High-performance liquid chromatography (HPLC) can be used to determine the:

Which polysaccharide(s) can the enzyme α\alphaα -amylase break?

Which monosaccharides is NOT a carboxylic acid?

Which statement accurately describes the interactions between the molecules thrombin, antithrombin, and heparan sulfate?

Which polysaccharide is NOT a homopolysaccharide?

Which description of a ganglioside is MOST accurate?

In amylose, the most stable structure is a _____, which is stabilized by _____.

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

The severalfold greater incidence of gastric ulcers in _____ is due in part to a surface lectin in the bacterium Helicobacter pylori.

Of the 16 possible aldohexoses, 8 are D forms and 8 are L forms. However, most of the hexoses of living organisms are D isomers. Speculate in a few sentences the possible reason for this preference.

The biochemical property of lectins that is the basis for most of their biological effects is their ability to bind to:

Several types of human joint and skeletal defects are a result of a defect in a biosynthetic enzyme responsible for synthesis of:

The reference compound for naming D and L isomers of sugars is:

What possible benefits are provided by extended conformation that the heteropolysaccharide glycosaminoglycans assume in solution?

Which statement about heparan sulfate is NOT true?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

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

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Which polysaccharide(s) can the enzyme $\alpha$ -amylase break?

In amylose, the most stable structure is a _, which is stabilized by _.