CHAPTER 3 ENERGY CATALYSIS AND BIOSYNTHESIS 2009 Garland Science Publishing Catalysis and the Use of Energy by Cells 3 1 Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment The specific subset of these reactions that breakdown nutrients in food can be described as a metabolic b catabolic c anabolic d biosynthetic 3 2 The second law of thermodynamics states that the disorder in any system is always increasing In simple terms you can think about dropping NaCl crystals into a glass of water The solvation and diffusion of ions is favored because there is an increase in a pH b entropy c ionic structure d stored energy 3 3 The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of a Brownian motion b heat c light waves d chemical bonds 3 4 At first glance it may seem that living systems are able to defy the second law of thermodynamics However on closer examination it becomes clear that although cells create organization from raw materials in the environment they also contribute to disorder in the environment by releasing a water b radiation c heat d proteins 3 5 If you weigh yourself on a scale one morning then eat four pounds of food during the day will you weigh four pounds more the next morning Why or why not Hint What happens to the atoms contained in the food as useful energy is derived from metabolizing the food molecules 3 6 Which of the following statements are true or false If a statement is false explain why it is false A The second law of thermodynamics states that the total amount of energy in the Universe does not change B The ultimate source of energy for living systems is chlorophyll C CO2 gas is fixed in a series of reactions that are light dependent D H2 is the most stable and abundant form of hydrogen in the environment 3 7 Two college roommates do not agree on the best way to handle the clutter piled up in your dorm room Roommate 1 explains that chaos is inevitable so why fight it Roommate 2 counters that maintaining an organized environment makes life easier in many ways and that chaos is not inevitable What law of thermodynamics drives the thinking of roommate 1 What thermodynamic argument can be used to support roommate 2 3 8 Assume that the average human adult requires 2000 kilocalories per day to sustain all normal processes and maintain a constant weight If manufactured solar panels could somehow provide power directly to the human body what size solar panel would be required in cm2 Assume there are 10 hours of sunlight per day and that the usable energy output for a typical solar panel is 850 kJ ft2 per hour Note 1 kcal 4 184 kJ 1 ft2 929 03 cm2 3 9 Fill in the blanks selecting from the choices below Light heat sugars CO CO2 O2 H2 H2O N2 NO 3 10 During respiration energy is retrieved from the high energy bonds found in certain organic molecules Which of the following in addition to energy are the ultimate products of respiration a CO2 H2O b CH3 H2O c CH2OH O2 d CO2 O2 3 13 For each of the pairs A D in Figure Q3 13 pick the more reduced member of the pair Figure Q3 13 3 14 Oxidation is the process by which oxygen atoms are added to a target molecule Generally the atom that is oxidized will experience which of the following with respect to the electrons in its outer shell a a net gain b a net loss c no change d an equal sharing 3 15 When elemental sodium is added to water the sodium atoms ionize spontaneously Uncharged Na becomes Na This means that the Na atoms have been a protonated b oxidized c hydrogenated d reduced 3 16 Arrange the following molecules in order with respect to their relative levels of oxidation assign 5 to the most oxidized and 1 to the most reduced CH2O formaldehyde CH4 methane CHOOH formic acid CH3OH methanol CO2 carbon dioxide 3 17 Oxidation and reduction states are relatively easy to determine for metal ions because there is a measurable net charge In the case of carbon compounds oxidation and reduction depend on the nature of polar covalent bonds Which of the following is the best way to describe these types of bond a hydrogen bonds in a nonpolar solution b covalent bonds in an aqueous solution c unequal sharing of electrons across a covalent bond d equal sharing of electrons across a covalent bond 3 18 Seed oils are often dehydrogenated and added back into processed foods as partly unsaturated fatty acids In comparison with the original oil the new fatty acids have additional double carbon carbon bonds replacing what were once single bonds This process could also be described as a isomerization b oxidation c reduction d protonation 3 20 Chemical reactions that lead to a release of free energy are referred to as energetically favorable Another common way in which these reactions are described is a uphill b uncatalyzed c spontaneous d activated 3 21 G indicates the change in the standard free energy as a reactant is converted to product Given what you know about these values which reaction below is the most favorable a ADP Pi ATP G 7 3 kcal mole b glucose 1 phosphate glucose 6 phosphate G 1 7 kcal mole c glucose fructose sucrose G 5 5 kcal mole d glucose CO2 H2O G 686 kcal mole 3 22 Catalysts are molecules that lower the activation energy for a given reaction Cells produce their own catalysts called a proteins b enzymes c cofactors d complexes 3 23 For each of the following sentences fill in the blanks with the best word or phrase selected from the list below Not all words or phrases will be used each word or phrase should be used only once By definition catalysis allows a reaction to occur more Chemical reactions occur only when there is a loss of energy Enzymes act more than other catalysts A catalyst decreases the energy of a reaction activation chemical bond completely selectively 3 24 free kinetic rapidly slowly unfavorable favorable Figure Q3 24 is an energy diagram for the reaction X Y Which equation below provides the correct calculation for the amount of free energy change when X is converted to Y a b c d a b c a b a c c a Figure Q3 24 3 25 Enzymes facilitate reactions in living systems Figure Q3 25 presents an energy diagram for the reaction X Y The solid line in the energy diagram represents changes in energy as the product is converted to reactant under standard conditions The dashed line shows changes observed when the same reaction takes place in the