1. Word origin. Account for the origin of the term carbohydrate.
2. Diversity. How many different oligosaccharides can be made by linking one glucose, one mannose,
and one galactose? Assume that each sugar is in its pyranose form. Compare this number with the
number of tripeptides that can be made from three different amino acids.
3. Couples. Indicate whether each of the following pairs of sugars consists of anomers, epimers, or
an aldose-ketose pair:
(a) d-glyceraldehyde and dihydroxyacetone
(b) d-glucose and d-mannose
(c) d-glucose and d-fructose
(d) α-d-glucose and β-d-glucose
(e) d-ribose and d-ribulose
(f) d-galactose and d-glucose
4. Tollen's test. Glucose and other aldoses are oxidized by an aqueous solution of a silver-ammonia
complex. What are the reaction products?
5. Mutarotation. The specific rotations of the α and β anomers of d-glucose are +112 degrees and
+18.7 degrees, respectively. Specific rotation, [ α ] d , is defined as the observed rotation of light of
wavelength 589 nm (the d line of a sodium lamp) passing through 10 cm of a 1 g ml-1 solution of a
sample. When a crystalline sample of α-dglucopyranose is dissolved in water, the specific rotation
decreases from 112 degrees to an equilibrium value of 52.7 degrees. On the basis of this result, what
are the proportions of the α and β anomers at equilibrium? Assume that the concentration of the
open-chain form is negligible.
6. Telltale adduct. Glucose reacts slowly with hemoglobin and other proteins to form covalent
compounds. Why is glucose reactive? What is the nature of the adduct formed?
7. Periodate cleavage. Compounds containing hydroxyl groups on adjacent carbon atoms undergo
carbon-carbon bond cleavage when treated with periodate ion (IO4 -). How can this reaction be used
to distinguish between pyranosides and furanosides?
8. Oxygen source. Does the oxygen atom attached to C-1 in methyl α-d-glucopyranoside come from
glucose or methanol?
9. Sugar lineup. Identify the following four sugars
12. Component parts. Raffinose is a trisaccharide and a minor constituent in sugar beets.
(a) Is raffinose a reducing sugar? Explain.
(b) What are the monosaccharides that compose raffinose?
(c) β-Galactosidase is an enzyme that will remove galactose residues from an oligosaccharide. What
are the products of β-galactosidase treatment of raffinose?
14. A taste of honey. Fructose in its β-d-pyranose form accounts for the powerful sweetness of
honey. The β-d-furanose form, although sweet, is not as sweet as the pyranose form. The furanose
form is the more stable form. Draw the two forms and explain why it may not always be wise to
cook with honey.
15. Making ends meet. (a) Compare the number of reducing ends to nonreducing ends in a molecule
of glycogen. (b) As we will see in Chapter 21, glycogen is an important fuel storage form that is
rapidly mobilized. At which end the reducing or nonreducing would you expect most metabolism to
take place?
16. Carbohydrates and proteomics. Suppose that a protein contains six potential N-linked
glycosylation sites. How many possible proteins can be generated, depending on which of these sites
is actually glycosylated? Do not include the effects of diversity within the carbohydrate added.
Chapter Integration Problem
17. Stereospecificity. Sucrose, a major product of photosynthesis in green leaves, is synthesized by a
battery of enzymes. The substrates for sucrose synthesis, d-glucose and d-fructose, are a mixture of
α and β anomers as well as acyclic compounds in solution. Nonetheless, sucrose consists of α-d-
glucose linked by its carbon-1 atom to the carbon-2 atom of β-d-fructose. How can the specificity of
sucrose be explained in light of the potential substrates?
