Ch. 12 outline - Ch. 12 Outline -The oxidation of metabolic...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 12 Outline - -The oxidation of metabolic fuels such as glucose, fatty acids, and amino acids, and the oxidation of acetyl carbons to carbon dioxide via the citric acid cycle yields the reduced cofactors NADH and ubiquinol. These compounds are forms of energy currency because their reoxidation-ultimately by molecular oxygen in aerobic organisms-is an exergonic reaction. The free energy thereby released is harvested to synthesize ATP, a phenomenon called oxidative phosphorylation. -Oxidative phosphorylation is a more indirect process in which free energy is temporarily stored, or conserved, in the form of a gradient of protons before being used to drive ATP synthesis. -The flow of electrons from reduced compounds such as NADH and QH2 to an oxidized compound such as oxygen is a thermodynamically favorable process. Look at Figure 12-1 The Thermodynamics of Oxidation-Reduction Reactions -In any oxidation-reduction reaction, one reactant is reduced as it gains electrons. The other reactant is oxidized as it gives up electrons. -In oxidation-reduction reactions involving the cofactor NAD+, the electron pair takes the form of a hydride ion. Reduction potential indicates a substance’s tendency to accept electrons -The affinity of a substance such as ubiquinone for electrons is its standard reduction potential(€), which has units of volts. -The greater the value of €, the greater the tendency of the oxidized form of the substance to accept electrons and become reduced. -Like a free energy value, the actual reduction potential depends on the concentrations of the oxidized and reduced species Look at Equation 12-1 Changes in reduction potential and free energy changes -Electrons flow spontaneously from the substance with the lower reduction potential to the substance with the higher reduction potential.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
-The larger the difference in € values, the greater the tendency of electrons to flow from one substance to the other, and the greater the change in free energy of the system. Look at Equation 12-3
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Ch. 12 outline - Ch. 12 Outline -The oxidation of metabolic...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online