Mitochondria and Oxidative Phosphorylation Flashcards
What makes up the proton motive force?
pH gradient from intermembranal space to matrix and transmembrane electrical potential (intermembranal space is more positive)
What makes up the ETC? Say in order of electron passing!!
3 complexes: NADH dehydrogenase complex, Cytochrome b-C1 complex and Cytochrome oxidase complex
2 mobile electron carriers: Co-enzyme Q (ubiquinone) and Cytochrome C
How does the electron affinity change along the ETC? How does this relate to redox potential?
each unit has a higher affinity for electrons than the previous so redox potential increases along ETC so successive members are more likely to accept electrons
How many electrons does co-enzyme Q pick up?
1 or 2 each with H+
Why does FADH2 produce less ATP?
electrons directly passed to co-enzyme Q so less H+ pumped
How does the cytochrome oxidase complex work?
LAST COMPLEX IN ETC
receives 2 electrons in first cycle and 2 more in second cycle so is holding 4 electrons
passes electrons to O2 to make H2O
4 protons pumped (4e- + 4H+ +2O2)
Why is oxygen terminal acceptor?
high affinity for electrons
What is the structure of ATP synthase?
Membrane bound (F0) - subunits a, b and c Matrix space (F1) - subunits alpha, beta and gamma
ATP synthase function(s)?
generate OR consume ATP (depends on mechanism direction)
How does ATP synthase generate ATP?
1) H+ flow into membrane via pore
2) c disc rotates, causing gamma disc to rotate as attached
3) alpha and beta in fixed position as locked by a and b
4) gamma is asymmetric so beta subunit changes structure
5) gamma ration drives transition of catalytic portion of beta subunit
6) ADP/ATP affinity altered
7) torsional energy flows from catalytic portion to bound ADP/Pi and promotes ATP formation
How does cyanide work?
high affinity for Fe3+ in haem group of cytochrome oxidase complex, binds and blocks electron flow to no ATP
How does malonate work?
competitively inhibits succinate dehydrogenase so slows electron flow from succinate to co enzyme Q by inhibiting succinate to fumarate (less FADH2)
How does oligomycin work?
binds with ATP synthase stalk so stops H+ flow through enzyme and synthesis inhibited. H+ backlog in intermembranal space so no more H+ pumped into spaces saturated and electrons not transported
How does DNP work?
uncouples Oxid. Phos. from ATP production by transporting H+ back across mitochondrial membrane rather than ATP synthase, increases metabolic rate and temperature
What was DNP used for?
weight loss
