Energy Transduction Questions

1995

"How can prokaryotes generate ATP under dark, anaerobic conditions?"

" 'The passage of electrons along what can be thought of as a wire
connecting NADH with oxygen results in ATP being produced in three
separate sites along this wire.'  Explain why such a traditional and
simple summary of oxidative phosphorylation is inadequate."

"Describe the events that commence following incidence of light in the
wavelength range 500-600nm on species of photosynthetic bacteria (other
than cyanobacteria and halobacteria) and that finish with the synthesis of
ATP.  To what extent are there similarities with the events that follow
identical illumination of green plant thylakoids?"

1996

"Describe how prokaryotes can generate ATP under aerobic conditions using
growth substrates other than fats, sugars, amino acids or TCA cycle
intermediates."

"Explain (i) How is it that the cytochrome b component of cytochrome bc
complexes of electron transfer chains is both reduced by ubiquinol and
oxidised by ubiquinone; and (ii) How the proton electrochemical gradient
(protonmotive force) across energy transducing membranes can be
estimated.   Why is knowledge of the magnitude of this gradient
important?"

1997

"Discuss the experimental approaches which have been used to investigate
components of electron transport chains."

"The system for trapping light energy in photosynthesis is perhaps the
best characterised system of membrane proteins.  Compare the structures
involved in light trapping in green plants with those in purple
non-sulphur bacteria."

1998

"What is meant by the term 'ion electrochemical gradient' across a
membrane?  Explain how such gradients are involved in a range of
biological processes."

"Compare and contrast the mechanisms of ion pumping by the F1 ATPase, the
sarcoplasmic reticulum Ca2+ ATPase, and cytochrome oxidase."

1999

"We know a great deal about the mechanisms used by complex III (cytochrome
bc1) and complex IV (cytochrome aa3 oxidase) to generate a protonmotive
force in mitochondria.  However, we know very little about how this is
achieved by complex I (NADPH-ubiquinone oxidoreductase).  Discuss."

"How are the actions of photosystems I and II coordinated in plant
chloroplasts (a) to ensure the balance of electron flow along the electron
transfer chain, and (b) to ensure and appropriate supply of NADPH and ATP
to the Calvin cycle?"

"Explain how (a) hydrogen + methanol; (b) oxygen + methanol; (c) hydrogen
+ sulphate; and (d) Fe(II) + oxygen can be used by different species of
bacteria to generate ATP."

2000

"Compare and contrast the structure of photosystem I and II in green
plants.  How far can the structural differences between them be explained
in terms of their different functions?"

"Explain how (a) membrane potentials and (b) pH gradients across membranes
can be estimated.  Why is knowledge of these gradients important?"