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## Chapter 18 Carbohydrates ### Section 18-10 Quick Quiz 1. How many different forms of a D-monosaccharide are present, at equilibrium, in an aqueous solution of the monosaccharide? * one * two * **three** * no correct response 2. Which of the following structures represents a beta...

## Chapter 18 Carbohydrates ### Section 18-10 Quick Quiz 1. How many different forms of a D-monosaccharide are present, at equilibrium, in an aqueous solution of the monosaccharide? * one * two * **three** * no correct response 2. Which of the following structures represents a beta-monosaccharide? * CH2OH HO - OOH OH OH OH HO OH * **CH2OH HO -OOH OH OH OH HO OH** * HOCH2 OH OH OH * no correct response 3. Which carbon atom, by number, is the anomeric carbon atom in the structure CH2OH -OOH * carbon 2 * carbon 3 * **carbon 4** * no correct response 4. The cyclic forms of an aldohexose are based on a ring system containing * 6 C atoms * **5 C atoms and 1 O atom** * 4 C atoms and 2 O atoms * no correct response 5. Which of the following types of monosaccharides have cyclic forms that involve a five-membered ring? * aldopentoses and ketopentoses * **aldopentoses and ketohexoses** * aldohexoses and ketopentoses * no correct response **Answers:** 1. c; 2. b; 3. d; 4. b; 5. b ### Figure 18-18 Walter Norman Haworth (1883-1950) Walter Norman Haworth (1883-1950), the developer of Haworth projection formulas, was a British carbohydrate chemist. He helped determine the structures of the cyclic forms of glucose, was the first to synthesize vitamin C, and was a corecipient of the 1937 Nobel Prize in Chemistry. ### 18-11 Haworth Projection Formulas **Learning Focus** Be able to convert Fischer projection formulas to Haworth projection formulas. The structural representations of the cyclic forms of monosaccharides found in the previous section are examples of Haworth projection formulas. **A Haworth projection formula** is a two-dimensional structural notation that specifies the three-dimensional structure of a cyclic form of a monosaccharide. Such projections carry the name of their originator, the British chemist Walter Norman Haworth (Figure 18-18). In a Haworth projection, the hemiacetal ring system is viewed "edge on" with the oxygen ring atom at the upper right (six-membered ring) or at the top (five-membered ring). | | | |---|---| | 4 | 5 | | O | O | | 3 | 1 | | 2 | 2 | | 3 | 1 | | | 4 |