1. Draw the structure of D-erythrose as (1) a Fischer Projection (2) a wedge-and-dash structure and (3) a Newman projection. What kind of conformation does this represent? How many stereocenters does D-erythrose have? How many stereoisomers are there? How many diastereoisomers? Draw the Fischer structures of the other stereoisomers of D-erythrose. Which one is L-erythrose? Why is erythrose termed an "aldotetrose"?

2. Draw the Fischer structures of all of the diastereoisomeric D- aldopentoses. Which one is D-ribose? Which one is D-arabinose?

3. Draw the Fischer structures of D-glucose, D-mannose, and D-fructose. Number the carbon atoms of each. Explain and sketch mechanistically how D-glucose can be converted to D-mannose? Can D-glucose be readily converted to L-glucose? If so, how? Show how D-glucose and D-mannose can be converted, in part, to D-fructose.

4. Draw the conformational structures of D-glucopyranose and D-mannopyranose. Which one is more thermodynamically stable? Why? Of the two anomers of D-glucopyranose, which is imore stable, the alpha or beta? Why? What principle is involved? Explain, on thermodynamic grounds, why the cyclic hemiacetal form is favored over the acyclic form. In forming the cyclic hemiacetal form, which hydroxyl group of the acyclic form must add to the carbonyl group in order to give the six-membered ring?

5. Explain why, when pure b-D-glucopyranose is dissolved in water, the specific rotation gradually changes and then becomes steady. Explain why this steady state specific rotation is the same whether we start with the alpha or beta anomer. What is this phenomenon called? Sketch the mechanism for the interconversion of the alpha and beta anomers. What key intermediate is involved?

6. Write a mechanism for the conversion of b-D-glucopyranose to the corresponding methyl glycoside, by reaction with methanol in water. What kind of linkage is present in a glycoside?

7. Why is b-D-glucopyranose also called "dextrose". Does the "D" in b-D-glucopyranose imply that its rotation is positive? Why or why not?

8. Draw the structure of D-ribofuranose. Why is is termed "furanose" and not "pyranose"? Which hydroxyl group of the acyclic form of D-ribose must add to the aldehyde function to form the furanose ring. Which one would have to add to form an aldopyranose structure? Which form occurs in RNA? Is this because the aldopyranose structure is too unstable? Under what conditions can D-ribopyranose be formed?

9. Draw the structures of maltose and cellobiose and identify both the acetal and the hemiacetal linkages of each. Which linkage makes these disaccharides "reducing sugars"? Why? Why are these called "disaccharides"? Which alcohol function of D-glucopyranose reacts to form the acetal function on the other D-glucopyranose? Is there more than one isomer of maltose, e.g.? Explain and draw the structures of any isomers which are still called maltose.

10. Draw the repeat structures of cellulose and starch (amylose) and point out the structural differences and any differences in stability.

11. Look at the structure of sucrose in your book. What two simple sugars are combined to generate this disaccharide? Is this sugar a "reducing sugar"? Why or why not? Point out any functional groups in this disaccharide other than simple alcohol functions.

12. Draw the structure of D-deoxyribose. Where is it found in nature. To which carbon are the bases bound? The phosphate moieties?