Deck 23: Carbohydrates and Nucleic Acids

Question 1

L-Ribulose may be classified as ________.

A) an aldotetrose
B) an aldopentose
C) an aldohexose
D) a ketotetrose
E) a ketopentose

Answer 1

a ketopentose

Question 2

Draw the Fischer projection for the open-chain form of D-glucose.

Answer 2

Question 3

Draw the Fischer projection of the open chain form of L-allose.

Answer 3

Question 4

Draw the structure of D-glyceraldehyde.

Question 5

Given the structure of D-altrose below, draw the structure of L-altrose.

Question 6

Draw the Fischer projection for the open-chain form of D-erythrose.

Question 7

The structure of D-arabinose is shown below. Which of the following correctly describes the configurations of the asymmetric carbons in D-arabinose?

A) 2S, 3R, 4R
B) 2R, 3S, 4S
C) 2S, 3R, 4S
D) 2R, 3S, 4R
E) 2S, 3S, 4R

Question 8

Most monosaccharides are highly water soluble. Offer an explanation.

Question 9

Draw the cyclic hemiacetal form of D-glucose both as a chair conformation and as a Haworth projection.

Question 10

Which is the C2 epimer of D-glucose?

A)
B)
C)
D)

Question 11

Draw the Fischer projection of the open chain form of D-arabinose.

Question 12

How many asymmetric centers are present in the open chain form of the aldohexose D-(-)-gulose?

A) 0
B) 1
C) 2
D) 4
E) 5

Question 13

All naturally occurring sugars can be degraded to ________.

A) D-(-)-glyceraldehyde
B) D-(+)-glyceraldehyde
C) L-(-)-glyceraldehyde
D) L-(+)-glyceraldehyde
E) none of the above

Question 14

Draw the Fischer projection for the open-chain form of D-fructose.

Question 15

All chiral D-sugars rotate plane-polarized light ________.

A) clockwise
B) counterclockwise
C) +20.0°
D) in a direction that cannot be predicted but must be determined experimentally
E) since they are optically inactive

Question 16

How many molecules of carbon dioxide and water are needed to make a molecule of glucose in photosynthesis?

A) 5 CO₂ and 5 H₂O
B) 5 CO₂ and 6 H₂O
C) 6 CO₂ and 6 H₂O
D) 6 CO₂ and 2 H₂O
E) 2 CO₂ and 2 H₂O

Question 17

Draw the C3 epimer of L-glucose.

Question 18

In the Fischer projection of D-(+)-glyceraldehyde, the hydroxyl group on the asymmetric carbon center is ________.

A) on the bottom
B) on the top
C) at the left
D) at the right
E) present as a hemiacetal

Question 19

Provide the structure of the open-chain form of D-galactose.

Question 20

Provide the structure of the open-chain form of L-altrose.

Question 21

Which of the following correctly describes the structural relationship between D-gulose and L-gulose?

A) diastereomers and epimers
B) diastereomers but not epimers
C) enantiomers
D) constitutional isomers
E) not isomers

Question 22

Identify the C₃ epimer of the sugar below drawn in its open chain (acyclic) Fischer projection.

A)
B)
C)
D)

Question 23

Draw the Fischer projection of (2S,3R)-2,3-dihydroxybutanoic acid, and label it as erythro or threo.

Question 24

Which of the following descriptions apply to both D-glucopyranose and L-galactopyranose?
I. They are both ketoses
II. They are both aldoses
III. They are enantiomers of each other
IV. They are diastereomers of each other
V. They are epimers of each other

A) I, III and V
B) II and III
C) I, IV and V
D) II and IV
E) II, IV and V

Question 25

Fructose forms ________.

A) a five-membered cyclic hemiacetal
B) a six-membered cyclic hemiacetal
C) a six-membered lactone
D) a five-membered lactone
E) none of the above

Question 26

Which of the following correctly describes the structural relationship between D-ribose and L-lyxose?

A) diastereomers and epimers
B) diastereomers but not epimers
C) enantiomers
D) constitutional isomers
E) not isomers

Question 27

Which of the following descriptions apply to both dihydroxyacetone and D-fructofuranose?
I. They are both ketoses.
II. They are both aldoses.
III. They are enatiomers of each other.
IV. They are diastereomers of each other.
V. They are epimers of each other.

A) I
B) II
C) I and III
D) II and IV
E) II, IV and V

Question 28

Draw the Haworth structure of β-D-ribofuranose.

Question 29

Stereoisomeric aldohexoses that differ in configuration at only a single carbon are ________.

A) meso compounds
B) threo sugars
C) enantiomers
D) constitutional isomers
E) epimers

Question 30

How many asymmetric carbons are present in α-D-ribopyranose?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 31

In a Haworth projection of a five-membered cyclic hemiacetal, ________.

A) the C6 carbon is drawn on the right
B) the C2 carbon is drawn on the left
C) the ring oxygen is drawn in the front
D) the ring oxygen is drawn in the back
E) all hydroxyls are always on the same side of the molecule

Question 32

Draw the Haworth structure of β-D-glucopyranose.

Question 33

Draw the Haworth structure of α-D-ribofuranose.

Question 34

Which of the following represents a pair of epimers?

A) D- and L-erythrose
B) D-erythrose and D-threose
C) D-arabinose and D-erythrose
D) D-arabinose and D-xylose
E) D-glyceraldehyde and D-threose

Question 35

Draw the Haworth structure of α-D-glucopyranose.

Question 36

Draw the more stable chair conformer of α-D-glucopyranose.

Question 37

When a monosaccharide reacts to give the pyranose form from its open-chain form, how many distinct pyranose forms are possible?

A) 1
B) 2
C) 2ⁿ, where n is the number of carbons present
D) 4n + 2, where n is the number of carbons present
E) 4

Question 38

Six-membered cyclic hemiacetals and five-membered cyclic hemiacetals are called, respectively, ________.

A) mannoses and xyloses
B) maltoses and arabinoses
C) pyranoses and furanoses
D) glyoses and fructoses
E) none of the above

Question 39

In solution, glucose exists as ________.

A) the open-chain form only
B) the cyclic hemiacetal form only
C) an equilibrium mixture of the open-chain form and cyclic acetal forms
D) an equilibrium mixture of the open-chain form and cyclic hemiacetal forms

Question 40

A diastereomer is called erythro if its Fischer projection shows similar groups ________.

A) opposite each other on the same carbon
B) equally spaced about a central carbonyl
C) directly above and below a central carbonyl
D) on the same side of the molecule on adjacent carbons
E) on opposite sides of the molecule on adjacent carbons

Question 41

Draw the Haworth structure of the α-pyranose form of the monosaccharide shown below.

Question 42

Draw the Haworth structure of the α-furanose form of the monosaccharide shown below.

Question 43

What reagents are needed to induce the following isomerization?

A) NaOH
B) Br₂ / H₂O
C) HCl (aq)
D) PCC

Question 44

Reduction of a 2-ketohexose with NaBH₄ yields ________.

A) a single aldohexose
B) a mixture of acetals
C) a mixture of alditols
D) a mixture of cyclic hemiacetals
E) a single pyranose

Question 45

When L-erythrose is treated with NaBH₄, ________.

A) a 70:30 mixture of enantiomeric alditols results
B) a 50:50 mixture of enantiomeric alditols results
C) a meso alditol is produced
D) the product mixture contains two diastereomeric alditols
E) an optically active alditol is produced

Question 46

Anomers of D-glucopyranose differ in their stereochemistry at ________.

A) C5
B) C4
C) C3
D) C2
E) C1

Question 47

Draw the Haworth structure of the α-pyranose form of the monosaccharide shown below.

Question 48

Draw the Haworth structure of the β-furanose form of the monosaccharide shown below.

Question 49

How might one separate α-D-glucopyranose from a solution also containing

Question 50

The α and β anomers of a D-glucopyranose are related as ________.

A) enantiomers
B) meso compounds
C) structural isomers
D) epimers
E) disaccharides

Question 51

When pure α-D-glucopyranose is dissolved in water, the optical rotation of the resulting solution changes over a period of time. What is the name of this phenomenon and why does it occur?

Question 52

Show the Haworth of α-L-fructofuranose and the Fischer diagram of L-fructose.

Question 53

Draw the product of the following reaction in a Fischer projection.

Question 54

Draw the Haworth structure of the α-pyranose form of the monosaccharide shown below.

Question 55

What are the two most common unwanted side reactions which can occur when monosaccharides are treated with base?

A) epimerization and enediol rearrangement
B) mutarotation and epimerization
C) enediol rearrangement and glycoside formation
D) Kiliani-Fischer and Ruff degradations
E) Ruff degradation and glycoside formation

Question 56

What is the result of reaction involving D-glyceraldehyde and NaBH₄?

A) propane
B) ethanol and CO₂
C) dihydoxyacetone
D) glyceric acid
E) glycerol

Question 57

Provide the Haworth structure of β-D-ribopyranose.

Question 58

Draw the Haworth structure of the α-furanose form of the monosaccharide shown below.

Question 59

Draw the Haworth structure of the β-pyranose form of the monosaccharide shown below.

Question 60

A pyranose with the hydroxyl group on the anomeric carbon pointing up in the Haworth structure is designated ________.

A) a'
B) b'
C) α
D) β
E) γ

Question 61

When L-(+)-idose is treated with bromine water, which of the following results?

A) a racemic mixture of aldaric acids
B) an optically active aldaric acid
C) an optically inactive aldaric acid
D) an optically active aldonic acid
E) an optically inactive aldonic acid

Question 62

What is the major organic product of the following reaction?

Question 63

What is the major organic product of the following reaction?

Question 64

When D-(+)-allose is treated with bromine water, which of the following results?

A) a racemic mixture of aldaric acids
B) an optically active aldaric acid
C) an optically inactive aldaric acid
D) an optically active aldonic acid
E) an optically inactive aldonic acid

Question 65

When D-(+)-xylose is treated with nitric acid, which of the following results?

A) a racemic mixture of aldaric acids
B) an optically active aldaric acid
C) an optically inactive aldaric acid
D) an optically active aldonic acid
E) an optically inactive aldonic acid

Question 66

Provide the structure of the product which results when D-ribose is treated with bromine water.

Question 67

Which of the following statements is true?

A) All monosaccharides in either the ketose of aldose family are reducing sugars.
B) Only aldoses, but not ketoses, are reducing sugars.
C) Only ketoses, but not aldoses, are reducing sugars.
D) All disaccharides, not monosaccharides, are reducing sugars.
E) All glycosides are reducing sugars.

Question 68

What is the major organic product of the following reaction?

Question 69

What is the outcome of the following reaction?

A) No Reaction
B)
C)
D)

Question 70

Under what conditions is the methyl glycoside of galactose prepared?

Question 71

Draw the Haworth structure of methyl α-D-xylofuranoside.

Question 72

_{Which of the following would give a positive Tollen's test?}

A) α-D-glucopyranose
B) methyl β-D-glucopyranoside
C) sucrose
D) methyl α-D-ribofuranoside
E) none of the above

Question 73

When L-(+)-lyxose is treated with nitric acid, which of the following results?

A) a racemic mixture of aldaric acids
B) an optically active aldaric acid
C) an optically inactive aldaric acid
D) an optically active aldonic acid
E) an optically inactive aldonic acid

Question 74

Draw the Haworth structure of ethyl β-D-galactopyranoside.

Question 75

Under what conditions is the methyl glycoside of galactose hydrolyzed?

Question 76

Provide the Fischer projection of the open-chain form of the aldonic acid which results when L-glucose is treated with bromine water.

Question 77

Which of the following is a reducing sugar?

A) α-D-fructofuranose
B) the methyl glycoside of cellobiose
C) ethyl β-D-glucopyranoside
D) methyl α-D-fructofuranoside
E) none of the above

Question 78

Will methyl-β-D-talopyranoside undergo mutarotation? Why or why not?

Question 79

The open-chain form of D-talose is shown below. Draw the chair form of methyl β-D-talopyranoside.

Question 80

An aglycone is a group bound to ________.

A) the oxygen of C6 in a glycoside
B) the anomeric carbon in a glycoside
C) a pyrimidine base
D) a purine base
E) a xanthate