You isolate some mitochondria using differential centrifugation, and are able to

Question

You isolate some mitochondria using differential centrifugation, and are able to digest the outer membranes, leaving the rest of the organelles intact. The pH inside the inner membranes is 7.5. You transfer your "stripped" mitochondria from a pH 7.5 buffer to a solution whose pH is measured at 4.0 (pH 7.5 is maintained inside the membranes). Through biochemical assays, you are able to detect that ATP is being synthesized inside the membranes while the organelles are in pH 4.0 buffer, even though no electron transport is going on. Explain how this is possible. In class, we saw how we could calculate the approximate ATP yield per glucose going through the aerobic cellular respiration process (it was typically 36, but you already knew that!). Using similar methodology and the "exchange rates" we established in class (1 NADH rightarrow 3 ATP and 1 FADH_2 rightarrow 2 ATP), calculate how many ATP would be made from the breakdown of a single molecule of a fatty acid (not a fat/triglyceride) which has a hydrocarbon "tail" 12 carbons in length. To avoid unnecessary confusion, ignore the NADH and FADH_2 produced and the ATP used during beta-oxidation. Use the figure of the "metabolic pool" in your text to determine where the product of fatty acid breakdown enters the aerobic pathway, and go from there. Show all your work and calculations, and don't be intimidated.

Explanation / Answer

1.in nature the intermembrane space of mitochondria shows H+ ion gradient which is also considered important for generation of ATP,

in the above trial inner membrane is still intact also note that it has been transferred in low pHthat means there are more of H= ions creating the same proton gradient and hence ATP synthesis is not altered

2.

i) first try to find out how much acetyl coA is formed , for that yo should divide number of carbons in your fatty acid by 2 so here it will be 12/2 is equal to 6 acetyl coA

ii) number of cycles required in the beta oxidation to convert the complete fatty acid into acetyl coA ... so its like this number of aceyl coA minus 1

here it will be 6-1 = 5 cycles

iii) suppose ifeach NADHgives 2.5 ATP and FADH@ yields 1.5 ATP then multiply cycles by 4 and number of acetyl coA by 10

here it will be (5x4) + (6x10)= 80

iv) now subtract two ATP that were used for the activation of the Fatty Acid

so final ATP yield is 80-2 = 78 ATP

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