New York University BIOCHEMIST 406 1)How many amino sugars are common in nature? 1 2 3 4 The D- form of which of the following amino sugars is not commonly found naturally? galactosamine glucosamine mannosamine ribosamine The D- form of which of the following amino sugars is commonly found naturally? allosamine althrosamine mannosamine none of these To which carbon of a monosaccharide is the amino group bound in the amino sugars commonly found in nature? C-1 C-2 C-5 C-6 Which of the following functional groups is present in N-acetylglucosamine? amide 1? amine 2? amine 3? amine Approximately how many infants are born with galactosemia? A

Question

New York University

BIOCHEMIST 406

1)How many amino sugars are common in nature?

The D- form of which of the following amino sugars is not commonly found naturally?
1. galactosamine
2. glucosamine
3. mannosamine
4. ribosamine

The D- form of which of the following amino sugars is commonly found naturally?
1. allosamine
2. althrosamine
3. mannosamine
4. none of these

To which carbon of a monosaccharide is the amino group bound in the amino sugars commonly found in nature?
1. C-1
2. C-2
3. C-5
4. C-6

Which of the following functional groups is present in N-acetylglucosamine?
1. amide
2. 1? amine
3. 2? amine
4. 3? amine

B. 1 in 1.8 ´ 10⁴

C. 1 in 1.8 ´ 10³

D. 1 in 1.8 ´ 10⁵

Which of the following is a generally mild disease?
1. galactosemia
2. galactosuria
3. both (a) and (b)
4. neither (a) nor (b)

Which of the following is a severe disease?
1. galactosemia
2. galactosuria
3. both (a) and (b)
4. neither (a) nor (b)

For the solvents water, ethanol, and benzene which gives the correct order of solubility of monosaccharides?
1. benzene > ethanol > water
2. benzene > water > ethanol
3. water > ethanol > benzene
4. water > benzene > ethanol

The cyclic structures of monosaccharides are which of the following?
1. acetals
2. hemiacetals
3. ethers
4. esters

What is the relationship between the number of stereocenters in a monosaccharide in its open-chain and ring structures?
1. the two structures contain the same number of stereocenters
2. the open-chain form contains one less stereocenter than does the ring
3. the open-chain form contains one more stereocenter than does the ring
4. there is no general relationship, each case must be considered separately

Which of the following is associated with the projections commonly used to illustrate furanoses and pyranoses?
1. E. Fischer
2. W. Haworth
3. L. Pauling
4. L. Pasteur

When an aldohexose such as glucose adopts the pyranose structure which atoms are connected by an oxygen atom?
1. C-1 and C-5
2. C-1 and C-6
3. C-2 and C-5
4. C-2 and C-6

When a ketohexose such as fructose adopts the furanose structure which atoms are connected by an oxygen atom?
1. C-1 and C-5
2. C-1 and C-6
3. C-2 and C-5
4. C-2 and C-6

When an aldopentose such as ribose adopts the pyranose structure which atoms are connected by an oxygen atom?
1. C-1 and C-3
2. C-1 and C-4
3. C-2 and C-3
4. C-2 and C-4

The sugars in RNA and DNA are ribose and deoxyribose respectively. Which of the following describes the relationship between these two sugars?
1. in deoxyribose the oxygen lost is from the hydroxyl on C-1 of ribose
2. in deoxyribose the oxygen lost is from the hydroxyl on C-2 of ribose
3. in deoxyribose the oxygen lost is from the hydroxyl on C-3 of ribose
4. in deoxyribose the oxygen lost is from the hydroxyl on C-4 of ribose

When glucose adopts a pyranose structure which carbon is the anomeric carbon?
1. C-1
2. C-2
3. C-5
4. C-6

When fructose adopts a furanose structure which carbon is the anomeric carbon?
1. C-1
2. C-2
3. C-5
4. C-6

When ribose adopts a furanose structure which carbon is the anomeric carbon?
1. C-1
2. C-2
3. C-5
4. C-6

Which of the following is true of the spatial distribution of the hydroxyl groups of b-D-glucopyranose?
1. they are all in axial positions
2. they are all in equatorial positions
3. the hydroxyl on C-1 is axial, those on C-2, C-3 and C-4 are equatorial
4. the hydroxyl on C-1 is equatorial, those on C-2, C-3 and C-4 are axial

Which of the following is true of the spatial distribution of the hydroxyl groups of a-D-glucopyranose?
1. they are all in axial positions
2. they are all in equatorial positions
3. the hydroxyl on C-1 is axial, those on C-2, C-3 and C-4 are equatorial
4. the hydroxyl on C-1 is equatorial, those on C-2, C-3 and C-4 are axial

Which sugar is the starting material used by plants to synthesize vitamin C?
1. D-fructose
2. L-fructose
3. D-glucose
4. L-glucose

Which of the following is true of the a and b anomers of glucose?
1. they have equal but opposite optical rotations
2. they are equally stable
3. both (a) and (b)
4. neither (a) nor (b)

Which of the following is true of the a and b anomers of glucose?
1. they both rotate light to the right (i.e. +), but not to the same extent
2. they are equally stable
3. both (a) and (b)
4. neither (a) nor (b)

Which of following describes a solution in which the a and b anomers of glucose have reached equilibrium?
1. there are equal amounts of the two anomers
2. the solution shows no optical activity
3. both (a) and (b)
4. neither (a) nor (b)

Which of following describes a solution in which the a and b anomers of glucose have reached equilibrium?
1. there is more b anomer present than a anomer
2. the solution shows no optical activity
3. both (a) and (b)
4. neither (a) nor (b)

Which carbon is the site of reaction when glucose reacts to form a glucoside?
1. C-1
2. C-2
3. C-5
4. C-6

Which carbon is the site of reaction when fructose reacts to form a fructoside?
1. C-1
2. C-2
3. C-5
4. C-6

Which of the following reacts with sugars to form glycosides?
1. alcohols
2. amines
3. hemiacetals
4. water

Glycosides are examples of which class of compounds?
1. acetals
2. hemiacetals
3. ethers
4. esters

ANS: A

The formation of a glycoside from a sugar is an which of the following reactions?
1. condensation
2. hydrolysis
3. reduction
4. oxidation

Which of the following explains why glycosides do not undergo mutarotation?
1. there is no longer an anomeric carbon
2. there are no longer any stereocenters
3. the ring structure does not open to become the open-chain structure
4. none of the above

Which of the following reagents is capable of hydrolyzing glycosides?
1. acids
2. bases
3. water
4. all of these

What reaction occurs when glucose is converted to glucitol?
1. reduction at C-1
2. oxidation at C-1
3. reduction at C-6
4. oxidation at C-6

Which of the following is true of glucitol?
1. it exists only as an open-chain structure
2. it exists only as a ring structure
3. it exists as both ring and open-chain structures with the open-chain structure predominating
4. it exists as both ring and open-chain structures with the ring structure predominating