Ch.23 - Organic and Biological Chemistry
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- One of the constituents of the carnauba wax used in floor and furniture polish is an ester of a C32 straight-chain alcohol with a C20 straight-chain carboxylic acid. Draw the structure of this ester.
Problem 95
- What amino acids do the following abbreviations stand for? (a) Ser (b) Thr (c) Pro (d) Phe (e) Cys
Problem 114
- Name and draw the structures of amino acids that fit the following descriptions. (a) Contains an isopropyl group (b) Contains an alcohol group (c) Contains a thiol group (d) Contains an aromatic ring
Problem 115
- Use the three-letter abbreviations to name all tripeptides containing methionine, isoleucine, and lysine.
Problem 118
- How many tetrapeptides containing alanine, serine, leucine, and glutamic acid can you form? Use the three-letter abbreviations to name three.
Problem 119
- What is a nucleotide, and what three kinds of components does it contain?
Problem 126
- What are the names of the sugars in DNA and RNA, and how do they differ?
Problem 127
- Show by drawing structures how the sugar and nitrogenous base components of a nucleic acid are joined.
Problem 129
- The DNA from sea urchins contains about 32% A and about 18% G. What percentages of T and C would you expect in sea urchin DNA? Explain.
Problem 131
- Fumaric acid is an organic substance widely used as a food additive. Its elemental composition is 41.4% C, 3.5% H, and 55.1% O. A solution made by dissolving 0.1500 g of fumaric acid in water and diluting to a volume of 100.0 mL gave rise to an osmotic pressure of 240.3 mm Hg at 298 K. On titration of a sample weighing 0.573 g, 94.1 mL of 0.105 M NaOH was required to reach an equivalence point. Fumaric acid reacts with 1 mol of H2 to give a hydrogenation product. (a) What is the empirical formula of fumaric acid? (b) What is the molecular weight of fumaric acid? (c) Draw three possible structures for fumaric acid. (d) If fumaric acid contains a trans double bond, which of your structures is correct?
Problem 135
- Cytochrome c is an important enzyme found in the cells of all aerobic organisms. Elemental analysis of cytochrome c shows that it contains 0.43% iron. What is the minimum molecular weight of this enzyme?
Problem 136
- Cyclohexane, C6H12, is an important starting material used in the industrial synthesis of nylon. Each carbon has four covalent bonds, two to hydrogen and two to other carbons. Draw the structural formula of cyclohexane.
Problem 143
Problem 144
Isooctane, the substance in gasoline from which the term octane rating derives, has the formula C8H18. Each carbon has four covalent bonds, and the atoms are connected in the sequence shown. Draw the complete structural formula of isooctane.