oxphos Flashcards
where is oxphos carried out?
mitochondria (protein complexes in inner membrane)
what is the function of oxphos?
generate ATP from reducing equivalents (NADH, FADH2 fr glycolysis & TCA cycle)
how does NADH fr glycolysis [cytoplasm] enter mitochondria? (2)
shuttles:
1. glycerol-3-phosphate shuttle: brings NADH in as FADH2 (fast but less ATP eg muscles)
2. malate-aspartate shuttle: brings NADH in as NADH (slow but more ATP eg cardiac/liver muscles)
which pumps in inner mitochondrial membrane are transmembrane + significance?
1, 3, 4
transmembrane→ can pump H+ across to maintain electrochemical gradient
where does electron get transferred in proton pump 1?
NADH to CoQ (CoQH2)
where does electron get transferred in proton pump 2?
FADH2 to CoQ (CoQH2)
where does electron get transferred in proton pump 3?
CoQH2→ cytochrome C (reduced)
where does electron get transferred in proton pump 4?
cytochrome C (reduced) to O2→ H2O! :)
O2 is final electron acceptor
how does electron get transferred from proton pumps 1 to 4 (summary)
NADH and FADH2 to CoQ→ cytochrome C→ O2⇒ H2O
how does ATP get synthesized from ETC?
proton gradient formed across inner mitochondrial membrane by pumping of H+ by pumps 1,3,4
H+ flow through ATP synthase catalyzes formation of ATP fr ADP+Pi
what is the breakdown of the total amt of ATP produced by glycolysis/TCA/oxphos per glucose molecule?
glycolysis: 2ATP
TCA cycle: 2ATP + 8NADH + 4FADH2
oxphos:
- 8NADH = 20ATP
- 4FADH2 = 6 ATP
total= 30ATP
what are the side products of oxphos (2)?
- reactive oxygen species (partial reduction of O2→ toxic derivatives)
- heat (short circuit UCP channel in brown fat allowing H+ to pass wo ATP synthase)
what enzymes help combat accumulation of toxic ROS?
- superoxide dismutase (superoxide)
- catalase (peroxide)
- glutathione peroxidase (peroxide)
how is ETC regulated?
based on ATP need:
high ATP consumption→ increase H+ flow→ decrease H+ gradient→ increase ETC flow
low ATP consumption opposite
what mitochondrial poisons inhibit what mechanisms of oxphos? (4)
Rotenone/Rat poison: ETC pump 1
Antimycin A/fish poison: ETC pump 2
Cyanide/CO: ETC pump 3
Dinitrophenol/herbicide/weight loss drug: increase proton leak against membrane→ short circuit→hyperthermia
Rats Are Cats Dinner