Carbohydrates

Question 1

When glucose is in a straight-chain formation, it:

A. is an aldoketose.
B. is a pentose.
C. has five chiral carbons.
D. is one of a group of 16 stereoisomers

Answer 1

D. is one of a group of 16 stereoisomers

Question 2

The formation of α-d-glucopyranose from β-d-glucopyranose is called:

A. glycosidation
B. mutarotation.
C. enantiomerization.
D. racemization.

Answer 2

mutarotation

Question 3

When the following straight-chain Fischer projection is converted to a chair or ring
conformation, its structure will be:

Answer 3

Question 4

Why is the α-anomer of d-glucose less likely to form than the β-anomer?

A. The β-anomer is preferred for metabolism.
B. The β-anomer undergoes less electron repulsion.
C. The α-anomer is the more stable anomer.
D. The α-anomer forms more in l-glucose.

Answer 4

B. The β-anomer undergoes less electron repulsion.

The hydroxyl group on the anomeric carbon of the β-anomer is equatorial, thereby creating less
steric hindrance than the α-anomer, which has the hydroxyl group of the anomeric carbon in
axial position.

Question 5

Why is the α-anomer of d-glucose less likely to form than the β-anomer?

A. The β-anomer is preferred for metabolism.
B. The β-anomer undergoes less electron repulsion.
C. The α-anomer is the more stable anomer.
D. The α-anomer forms more in l-glucose.

Answer 5

B. The β-anomer undergoes less electron repulsion.

The hydroxyl group on the anomeric carbon of the β-anomer is equatorial, thereby creating less
steric hindrance than the α-anomer, which has the hydroxyl group of the anomeric carbon in
axial position.

Question 6

The cyclic forms of monosaccharides are:

I. hemiacetals.
II. hemiketals.
III. acetals.

A. I only
B. III only
C. I and II only
D. I, II, and III

Question 7

Ketose sugars may have the ability to act as reducing sugars. Which process explains this?

A. Ketose sugars undergo tautomerization.
B. The ketone group is oxidized directly.
C. Ketose sugars undergo anomerization.
D. The ketone group is reduced directly.

Question 8

What is mutarotation

Answer 8

is the interconversion between anomers of a compound

Question 9

Andersen’s disease (glycogen storage disease type IV) is a condition characterized by a
deficiency in glycogen branching enzyme. Absence of this enzyme would be likely to cause
all of the following effects EXCEPT:

A. decreased glycogen solubility in human cells.
B. slower action of glycogen phosphorylase.
C. less storage of glucose in the body.
D. glycogen devoid of α-1,4 linkages

Answer 9

D. glycogen devoid of α-1,4 linkages