2–9 The molecular weight of ethanol (CH3CH2OH) is 46 and its density is 0.789 g/cm3.
2–4 If an oxidation occurs in a reaction, it must be a. What is the molarity of ethanol in beer that is 5% accompanied by a reduction.
ethanol by volume? [Alcohol content of beer varies from about 4% (lite beer) to 8% (stout beer).] 2–5 Linking the energetically unfavorable reaction A b. The legal limit for a driver’s blood alcohol content → B to a second, favorable reaction B → C will shift the varies, but 80 mg of ethanol per 100 mL of blood (usually equilibrium constant for the first reaction.
referred to as a blood alcohol level of 0.08) is typical. What 2–6 The criterion for whether a reaction proceeds is the molarity of ethanol in a person at this legal limit? spontaneously is ΔG not ΔG°, because ΔG takes into C. How many 12-oz (355-mL) bottles of 5% beer could account the concentrations of the substrates and products. a 70-kg person drink and remain under the legal limit? A 70-kg person contains about 40 liters of water. Ignore the 2–7 The oxygen consumed during the oxidation of glu-metabolism of ethanol, and assume that the water content cose in animal cells is returned as CO2 to the atmosphere. of the person remains constant.
activity (% of maximum)
D. Ethanol is metabolized at a constant rate of about 120 mg per hour per kg body weight, regardless of its concentration. If a 70-kg person were at twice the legal limit (160 mg/100 mL), how long would it take for their blood alcohol level to fall below the legal limit?
2–10 A histidine side chain is known to play an important role in the catalytic mechanism of an enzyme; however, it is not clear whether histidine is required in its protonated (charged) or unprotonated (uncharged) state. To answer this question you measure enzyme activity over a range of pH, with the results shown in Figure Q2–1. Which form of histidine is required for enzyme activity?
activity as a function of ph (problem 2–10).
2–11 The three molecules in Figure Q2–2 contain the seven most common reactive groups in biology. Most molecules in the cell are built from these functional groups. Indicate and name the functional groups in these molecules.
O Figure Q2–2 Three molecules that illustrate the seven most common functional groups in biology (problem 2–11). 1,3-Bisphosphoglycerate and
O pyruvate are intermediates in glycolysis and cysteine is an amino acid.
1,3-bisphosphoglycerate pyruvate cysteine 2–12 “Diffusion” sounds slow—and over everyday distances it is—but on the scale of a cell it is very fast. The average instantaneous velocity of a particle in solution—that is, the velocity between the very frequent collisions—is where k = 1.38 × 10–16 g cm2/K sec2, T = temperature in K (37°C is 310 K), and m = mass in g/molecule.
Calculate the instantaneous velocity of a water molecule (molecular mass = 18 daltons), a glucose molecule (molecular mass = 180 daltons), and a myoglobin molecule (molecular mass = 15,000 daltons) at 37°C. Just for fun, convert these numbers into kilometers/hour.
Before you do any calculations, try to guess whether the molecules are moving at a slow crawl (<1 km/hr), an easy walk (5 km/hr), or a record-setting sprint (40 km/hr).