1. Some photosynthetic bacteria are able to harvest 900-nanometer light (4 points).
A. What is the energy in kilocalories of a mole (an einstein) of 900-nanometer light?
B. What is the minimum number of 900 nanometer photons needed to form one molecule of ATP from ADP and inorganic phosphate? Assume a ƒ´G of 12 kilocalories per mole for the photo-phosphorylation reaction in bacteria. Hint: The question asks for the number of photons out of a mole of photons. Please show all calculations.
2. Describe the importance of the red drop/Emerson enhancement effect on the development of a workable model for photosynthetic electron transport in higher plants.
3. In the light reaction of photosynthesis, the capture of light energy results in the release and subsequent transfer of electrons. From what molecules are the electrons originally derived? In what molecule(s) do these electrons eventually reside?
4. Assuming a quantum requirement for photosynthesis of 8 (8 photons), calculate a thermodynamic efficiency in percent under standard conditions for the conversion of carbon dioxide to 3-phosphogylcerate if the wavelength of light used in 400 nm. To produce one mole of glucose from carbon dioxide and water requires +686 kcal of energy (6 CO2 + 6 H2O „³ 1 C6H12O6 + O2). Hint: First calculate the number of kcal required to reduce one molecule of carbon dioxide to 3-phospho-glycerate during step one of the Calvin cycle.
5. A. Write a balanced equation for the oxidation of ubiquinol by cytochrome c.
B. Calculate ƒ´Go¡¦ and ƒ´Eo¡¦ for the reaction.
6. Calculate ƒ´Go¡¦ for the oxidation of NADH by FAD.
7. Under standard conditions, will the following reactions proceed spontaneously as written? Why or why not?
Fumarate + NADH + H+ ⇄ succinate + NAD+
cytochrome a (Fe3+) + cytochrome b (Fe2+) ⇄ cytochrome a (Fe2+) + cytochrome b (Fe3+)
8. Under standard conditions, is the oxidation of free FADH2 by ubiquinone sufficiently exergonic to drive the synthesis of ATP? ƒ´Go¡¦ for ATP is -7.3 kcal/mole. Why or why not? Please show all work.