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REVIEW QUESTIONS AND EXERCISES 1

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REVIEW QUESTIONS AND EXERCISES 1. What are the three principal classes of animal food? 2. Life is dependent on four major classes of biomolecules. What are they? 3. Of the sugars listed in Table 20.1, which is the sweetest di- saccharide? Which is the sweetest monosaccharide? (Invert sugar is a mixture of glucose and fructose, so it should not be vu.) tatrace lzataan 5. Waar u 4. Indicate the three types of carbohydrates. Which is the simplest? JU: Ulve an example of each. 6. Classify the following as a monosaccharide, disaccharide, or polysaccharide: glucose, sucrose, maltose, fructose, cellulose, lactose, glycogen, galactose, starch, and ribose. 7. Draw structural formulas in the open-chain form for ribose, glu- cose, fructose, and galactose. 8. Draw structural formulas in the cyclic form for ribose, glucose, fructose, and galactose. 9. State the properties and the sources of ribose, glucose, fructose, and galactose. 10. The molecular formula for lactic acid is C3H603, and its struc- tural formula is CH3CH(OH)COOH. Is this compound a car- vonyurat: 04 promu. 11. What is the monosaccharide composition of (a) sucrose (d) starch (b) maltose (e) cellulose (c) lactose (f) glycogen 12. Draw structural formulas in the cyclic form for sucrose and maltose. 13. If the most common monosaccharides have the formula C6H12O6, why do the resulting disaccharides have the formula C12H22011, rather than C12H24012? 14. Write equations, using structural formulas in the cyclic form, for the hydrolysis of (a) sucrose (b) maltose What enzymes catalyze these reactions? 15. Discuss the similarities and differences between starch and cellulose. 16. In what form is carbohydrate stored in the body? 17. Discuss, in simple terms, the metabolism of carbohydrates in the human body. 18. State the natural sources of sucrose, maltose, lactose, and starch. 19. Invert sugar, obtained by the hydrolysis of sucrose to an equal- molar mixture of fructose and glucose, is commonly used as a sweetener in commercial food preparations. Why is invert sugar sweeter than the original sucrose? 20. Use molecular structure to explain the following: (a) Fructose is a ketone. (b) Glucose is an aldehyde. 21. What is the empirical formula for monosaccharides? 22. What change in oxidation state is experienced by the carbon in the combustion of sugar, C12H22011, to CO2? . auius IIIUIT Salulaicu 01 J. ITOW Can you uiSCLIWC WCICILE UCLwCCII All AMITO Dulu ailu ΠΙΟ ΙαιιΥ III vogtiavit VID unsaturated than those in animal fats? Explain your answer. (Table 20.2) 26. What properties of molecules cause them to be classified as lipids? 27. Write structural formulas for glycerol, stearic acid, palmitic acid, oleic acid, and linoleic acid. 28. Distinguish both chemically and physically between a fat and a vegetable oil. 29. What is a triacylglycerol? Give an example. 30. Write the structure for tristearin, a fat in which all the fatty acid units are stearic acid. 31. Write the structure of a triacylglycerol that contains one unit each of linoleic, stearic, and oleic acids. How many other for- mulas are possible in which the triacylglycerol contains one unit each of these acids? 32. Write equations for the saponification of (a) tripalmitin (a fat in which all the fatty acids are palmitic acid) (b) the triacylglycerol of Question 31. Which product(s) are soaps? 33. How can vegetable oils be solidified? What is the advantage of solidifying these oils? 34. What functions do fats have in the human body? 35. Which fatty acids are essential to human diets? saw the structural formula of cholesteroi. 37. Draw the ring structure that is common to all steroids. the formula for the triacylglycerol far (a) glycerol and butanoic acid (b) glycerol and one molecule each of stearic (CH3COOH), palmitic (C13H3COOH), and myristic (C13H2COOH) acids 39. In a linear peptide, what are the N-terminal residue and the C-terminal residue? urmary carboxylic acid? 57. What are enzymes, and what is their role in the body 5o. tic meant by specificity of an enzyme 59. Differentiate between the lock-and-key and induced-fit models for enzyme function. 60. What is meant by enzyme specificity? 61. What is the function of enzymes in the body? 62. What are the components of chromosomes? 63. In the four nucleotide units of DNA shown in Figure 20.6, which of these components are part of the backbone chain and which are off to the side: the nitrogen bases, the deoxyribose, and the phosphoric acid? 64. In the double-stranded helix structure of DNA, which bases are always hydrogen-bonded to the following: cytosine, thymine, adenine, and guanine? (Figure 20.7) 65. Write structural formulas for the compounds that make up DNA. 66. (a) What are the three units that make up a DNA nucleotide? (b) List the components of the four types of nucleotides found in DNA. (c) Write the structure and name of one of these nucleotides. 67. Briefly describe the structure of DNA as proposed by Watson and Crick. 68. What is the role of hydrogen bonding in the structure of DNA? 69. Explain the concept of complementary bases and how it relates to DNA. 70. A segment of a DNA strand has a base sequence of C-G-A-T- T-G-C-A. What is the base sequence of the other complemen- vary stranu of the double 71. Explain the replication process of DNA. DNA 10 genetics. 73. What are the three differences between DNA and RNA in terms 30.