Catabolic vs. anabolic states: ETC

[basophilic]

What do you expect to observe about the flow of electrons in the electron transport chain in a catabolic state vs. an anabolic state?

A. The flow of electrons will be faster in the catabolic state than the anabolic state.
B. The flow of electrons will be the same in the anabolic state and the catabolic state.
C. The flow of electrons will be faster in the anabolic state than the catabolic state.
D. The flow of electrons will be different in the anabolic state and the catabolic state, but it is not possible to know whether one will be increased or decreased.

Answer is C. KA's explanation is summarized as follows: anabolism --> increased ATP hydrolysis --> increased ADP and Pi --> increased substrate available for ATP synthase --> hence, faster electron flow in ETC. Vice versa for the catabolic state.

However, I find this a bit ambiguous. Everything would depend on at what STAGE you are in during the anabolic/catabolic states. For example, in early anabolic state, ATP concentration is still high, so ETC wouldn't be working as hard, but in late anabolic state a lot of ATP would be depleted so ETC should be working harder. I would agree with their reasoning if they said that the electron flow would ACCELERATE during anabolic state and DECELERATE during catabolic state. Am I misunderstanding?

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[kingtal0n]

The way I Would have guessed this one is that anabolic states are usually a state of excess, nutrient/energy is available to do work. So you would naturally just think that the transport chain would be working harder/faster to make use of all the excess energy (before something bad happens to it, imagine if an influx of glucose were to do the opposite-> slow things down, the excess glucose rapidly filtering into the blood stream could lead to serious problems if it is not removed effectively and converted to other forms of energy storage or burnt up.)

I Agree their answer is inadequate, the metabolic pathways are far too criss-crossy in nature to make many bland assumptions about these states. Some cells may prefer different pathways or depend on by-products not normally produced in other cells, and so on.

 

[Axes]

Doesn't increased substrate just increase the rate of ATP synthase activity? Why does it also affect electron flow rate