Deck 11: Carbohydrates

Question 1

Two monosaccharides that differ in stereochemistry at only a single asymmetric carbon are called _____.

A) aldoses
B) epimers
C) anomers
D) pentoses
E) enantiomers

Answer 1

B

Question 2

In N-linked glycoproteins, the carbohydrate portion is attached to a(n)_____________ residue in the protein.

Answer 2

asparagine

Question 3

The influenza virus recognizes _______________ (a carbohydrate) residues of glycoproteins present on cell surface.

Answer 3

sialic acid

Question 4

Fehling's solution is used to differentiate between reducing and nonreducing sugars. Which type of ion in Fehling's solution allows for this differentiation?

A) cupric
B) sodium
C) iodide
D) hydroxide
E) bicarbonate

Question 5

A _______________ is a stereoisomer that is not a mirror image.

Question 6

Which of the following terms describes a class of compounds with the molecular formula (CH₂O)_n?

A) proteoglycans
B) glycogen
C) mucoproteins
D) polysaccharides
E) monosaccharides

Question 7

What term describes stereoisomers that are mirror images of each other?

A) anomers
B) epimers
C) enantiomers
D) diastereomers
E) meso compound

Question 8

Which of the following are proteins that bind to specific carbohydrate structures in order to facilitate recognition between proteins and cells?

A) mucoproteins
B) glycosaminoglycans
C) glycoproteins
D) lectins
E) proteoglycans

Question 9

What type of enzyme synthesizes oligosaccharides?

A) amylase
B) sucrase
C) glycosyltransferase
D) $\beta$ -galactosidase
E) protein kinase

Question 10

Which of the following is among the most abundant organic molecules in the biosphere?

A) glycogen
B) amylose
C) amylopectin
D) cellulose
E) chitin

Question 11

Which of the following is the storage form of glucose in animals?

A) glycogen
B) amylose
C) amylopectin
D) cellulose
E) chitin

Question 12

A _______________ is a five-membered ring formed from a monosaccharide.

Question 13

_______________ is a disaccharide composed of galactose and glucose joined by a β-1,4 glycosidic bond.

Question 14

Maltose is composed of two molecules of glucose linked together by a(n) ____________ glycosidic bond.

Question 15

When an open-chain aldose cyclizes into a ring, it forms a _______________.

Question 16

______is the class of glycoproteins with predominantly N-acetylgalactosamine moieties.

A) Glycosaminoglycans
B) Mucoproteins
C) Starch
D) Lectins
E) Proteoglycans

Question 17

Plant starch is composed of amylose, a linear polymer of glucose, and a branched polymer of glucose referred to as _______________.

Question 18

In C-type lectins, a _______________ acts as a bridge between the carbohydrate and the protein.

Question 19

A given protein with several potential glycosylation sites can have many different glycosylated structures called ________________.

Question 20

What molecule are most sugars attached to prior to their transfer to proteins?

A) GDP
B) GMP
C) AMP
D) UMP
E) UDP

Question 21

What are lectins?

A) proteins that bind the carbohydrates on glycoproteins and other macromolecules
B) proteins that promote cell-cell interaction
C) proteins found in animals, plants, and microorganisms
D) All of the answers are correct.
E) None of the answers is correct.

Question 22

How is the d or l configuration determined?

Question 23

List some of the reasons why carbohydrates are considered important molecules.

Question 24

At what location(s) within a cell is/are proteins glycosylated?

A) ribosome
D) lysosome
B) endoplasmic reticulum
E) endoplasmic reticulum and Golgi complex
C) Golgi complex

Question 25

Glycoform refers to

A) a single protein type that can have forms that differ only in their glycosylation.
B) glycoproteins from the same gene family.
C) a common core of sugars that can be found on many different proteins.
D) All of the answers are correct.
E) None of the answers is correct.

Question 26

The simplest carbohydrates are the 3-carbon molecules:

A) d- and l-glyceraldehyde.
B) dihydroxyacetone and d- and l-glyceraldehyde.
C) dihydroxyacetone and glycerate.
D) dihydroxyacetone and glycerol
E) None of the answers is correct.

Question 27

Common carbohydrates found in nature are

A) aldehydes with two or more hydroxyl groups.
B) ketones with two or more hydroxyl groups.
C) amines with two or more hydroxyl groups.
D) aldehydes with two or more hydroxyl groups and ketones with two or more hydroxyl groups.
E) All of the answers are correct.

Question 28

Which of the following is the anomer of β-d-glucopyranose?

Question 29

Draw the Haworth projections of the two pyranose forms of d-glucose.

Question 30

Sugars are commonly linked to which amino acid residues in glycoproteins?

A) tyrosine and asparagine
D) serine and glutamine
B) serine, threonine, and asparagine
E) threonine and glutamine
C) serine, tyrosine, and asparagine

Question 31

Draw the Fischer projection structures of all of the trioses.

Question 32

Which of the following explains how some viruses gain entry into specific cells?

A) by attaching to ion channels
B) by cleaving the glycosidic bonds of cell surface glycoproteins and altering protein shapes
C) by binding to glycoproteins on the cell surface that are unique to specific cells
D) All of the answers are correct.
E) None of the answers is correct.

Question 33

What is the difference between an enantiomer and a diastereoisomer? Give examples.

Question 34

Selectins are proteins that

A) selectively bind proteins destined for lysozomes.
B) aid in selection of proteins bound for the Golgi complex.
C) bind immune-system cells as part of the inflammatory response.
D) All of the answers are correct.
E) None of the answers is correct.

Question 35

An aldehyde and alcohol can react to form a

A) hemialdol.
D) All of the answers are correct.
B) hemiketal.
E) None of the answers is correct.
C) hemiacetal.

Question 36

The enzyme that digests amylopectin is

A) $\alpha$ -amylase.
B) amylopectinase.
C) cellulase.
D) invertase.
E) None of the answers is correct.

Question 37

The nutritional storage form(s) of glucose in plants is/are

A) glycogen.
B) amylose.
C) amylopectin.
D) cellulose.
E) amylose and amylopectin.

Question 38

Inhibitors against which viral enzyme have potential as anti-influenza agents?

A) Calnexin
D) All of the answers are correct.
B) Neuraminidase
E) None of the answers is correct.
C) Selectin

Question 39

Glycoproteins are normally

A) found on membranes.
D) All of the answers are correct.
B) secreted as extracellular proteins.
E) found on membranes and secreted as extracellular proteins.
C) found inside organelles.

Question 40

Fructose can cyclize to (a)

A) pyranose ring.
B) furanose ring.
C) both pyranose and furanose ring forms.
D) All of the answers are correct.
E) None of the answers is correct.

Question 41

How does a genetic mutation account for some of the different human blood types?

Question 42

Describe the mechanism by which N-linked sugars are synthesized and attached to proteins.

Question 43

What is the advantage of having different blood types within a species?

Question 44

Why is it more difficult to determine the structure of the oligosaccharides, when compared to amino acid sequences?

Question 45

Describe some of the functions of glycosaminoglycans and proteoglycans.

Question 46

What is the role of l-selectin when produced by an embryo?

Question 47

Draw the structure of lactose. Identify the monosaccharides involved, and identify the type of linkage in lactose.

Question 48

Compare the structures of amylopectin and amylose.

Question 49

What are the chemical and structural differences between cellulose and glycogen?

Question 50

What is the role of mannose 6-phosphate? What disease is caused by lack of this terminal sugar on glycoproteins?