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Unformatted text preview: lly oxidized, yielding low energy
(2) Some of the energy difference (ÄG) between pyruvate and CO2 is captured as 5
pairs of high energy electrons by NADH (4) or FADH2 (1), and a little bit as 1 GTP.
(3) But we still haven’t made all that ATP that the cell needs! The high energy
electrons, carried by 4NADH and 1FADH2 , can now enter the next stage: electron
<a bit of review about oxidation-reduction and how energy is carried by electron acceptors>
The transfer of a pair of electrons (plus a proton = a hydride ion) results in the reduction of a
previously oxidized molecule. For example, NAD+ (oxidized) + H: => NADH (reduced).
What does this mean?
Molecules can be ranked in quantitative order by how well they give up electrons. The more
easily they give up electrons, the stronger their reducing power. The more easily they accept
electrons, the stronger their oxidizing power. For example, in the TCA cycle, isocitrate is
converted to alpha-ketoglutarate plus a pair of electrons; these electrons are used to reduce a
better electron acceptor than isocitrate, namely NAD+, generating NADH.
If a pair of electrons is passed spontaneously from molecule A to molecule B, then A must be
a better electr...
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This note was uploaded on 06/12/2012 for the course BIOLOGY 231 taught by Professor Petethollenbeck during the Fall '10 term at Purdue University-West Lafayette.
- Fall '10
- cell biology