Assignment - metabolic integration and overviews
1. 1.00 g glucose is converted to palmitic acid. How much glucose is obtained?
2. How much does this process cost or produce? Give this in three ways:
i. in terms of ATP and reducing equivalents (NADH and FADH; i.e. do NOT convert these to ATP),
ii. Convert the reducing equivalents to ATP using the known vertebrate ETC - FoF1 stoichiometry, and then give an answer in J under standard state conditions.
iii. What is the actual free energy ΔG for the hydrolysis of ATP under these physiologically relevant conditions?
iv. use this value to calculate the actual energy yield in J under these conditions
3. What kinds of organisms can do this, and what kinds cannot?
4. How much glucose is obtained?
5. How much does this process cost or produce, once again expressing in both:
i. ATP and reducing equivalents
ii. J (under physiological conditions, using ΔG not ΔGo' as in 2.iv)
6. How much energy is obtained from the complete metabolism of 1.00 g glucose to CO2 via glycolysis - TCA - ETC - FoF1 ? Go all the way to ATP here, and express this in J under physiological conditions as in parts 2.iv or 5.ii above.
7. How much energy is obtained in this case (J; physiological)?
8. What is the energy efficiency of fat storage in this case?
9. How much glucose is obtained (g)? (this is not quite the same question as #4 - but not far off)
10. What is the C efficiency (i.e. moles of C returned/moles of C initial)?
11. How much energy is used/produced in this process in terms of
i. ATP and reducing equivalents.
ii. J (converting reducing equivalents to ATP, and then under physiological conditions)
12. What is the net cost/benefit of this process energetically, taking into account both the loss of C and its energy equivalent; as well as the energy consequences of the process.
13. Produce a graphical representation of the conservation of both energy and C for this process of fat as a storage compound. You have considerable latitude here, but do something simple, professional, as well as clear and explanatory.
14. How many photons does it take to produce 1.00 g of glucose (assuming no photorespiration)?
15. What fraction of these photons must be absorbed by PSI, and what fraction by PSII?
16. What is the energy value of these photons?
17. Compare this to the energy content of that glucose (i.e. #6 above) to get a figure for the "Energy Efficiency of life on Earth"
18. If photorespiration occurs at the rate of 10% of CO2 fixation (i.e. RUBISCO reacts with one O2 for every 10 CO2 molecules) how many photons are absorbed in total to make 1.00 g glucose? (You need to figure out how many photons are needed to produce the ATP and NADPH needed to do both photorespiration recovery and the CO2 fixation)
19. How does this affect the efficiency of life now? (i.e. revise #17)
20. Is the PSI/ PSII ratio changed?
21. How much photorespiration must occur to make the extra cost of C4 metabolism worthwhile?