electron extraction - potential energy of electron transferred when it moves
- reduction can move electron completely or change degree of sharing in a covalent bond
- electrons shared equally in C-H bonds because C and H have similar electronegativity
- when glucose forms CO2 and H2O, oxygen atoms attract electrons away from hydrogen/carbon
- oxygen more electronegative than hydrogen/carbon
- energy released when electrons move from a less electronegative atom to a more electronegative atom
- shift of electrons during oxidative respiration releases energy to create ATP
- reducing power - NADH can carry energy of electrons donated to it
- can pass along electrons and reduce other atoms
- reduces fatty acid precursors to form fats when ATP is plentiful
- releasing energy in stages is more efficient than releasing it all at once
electron transport chain - stage 4
- series of membrane-associated proteins
- NADH dehydrogenase - 1st protein to receive an electron
- ubiquinone - carrier that passes electrons to the bc1 complex
- bc1 complex - protein-cytochrome complex acting as a proton pump
- cytochrome c - carrier that passes electrons to cytochrome oxidase complex
- cytochrome oxidase complex - uses 4 electrons to reduce O2 so that it forms 2H2O w/ 4H
- NADH gives electrons to NADH dehydrogenase, FADH2 gives electrons to ubiquinone
- energy from electrons transports protons from the mitochondrial matrix into the intermembrane space
- NADH activates 3 pumps, FADH2 activates 2 pumps
chemiosmosis - process where diffusion force generates energy for ATP
- protons transported into the intermembrane space try to go back into matrix due to diffusion
- protons (ion) can only enter through ATP synthase, which uses proton gradient as an energy source
- reentry of protons powers the ATP synthase
- theoretical yield - 36 molecules of ATP formed
- 4 ATP from glycolysis (though 2 used during the process)
- 30 ATP from NADH (3 per NADH)
- 4 ATP from FADH2 (2 per FADH2)
- -2 ATP (to move NADH produced by glycolysis into the mitochondrian)
- actual yield - usually lower than 36
- some protons able to enter matrix w/o using ATP synthase
- proton gradient not used exclusively for ATP synthesis
- about 30 ATP actually created
- aerobic respiration harvests about 32% of energy in glucose
aerobic respiration regulation - ATP stops respiration through feedback inhibition
- high concentrations of ADP activates enzymes to stimulate ATP synthesis
- phosphofructokinase - main control point in glycolysis
- catalyzes conversion of fructose phosphate to fructose biphosphate
- 1st non-reversible step in glycolysis
- stimulated by high levels of ADP and citrate
- pyruvate decarboxylase - main control point in Krebs cycle
- inhibited by high levels of NADH
- citrate synthetase - catalyzes 1st reaction involving conversion of oxaloacetate and acetyl-CoA into citrate
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