oxidative phosphorylation Flashcards
(16 cards)
describe the structure of the mitochondrial inner membrane (2)
- selectively impermeable (freely permeable to O2, CO2 & H2O)
- 75% protein (ATP, ADP, pyruvate)
outline chemiosmosis (2)
- ETC and ATP synthesis are coupled by proton gradient across the inner mitochondrial membrane
- chemiosmosis is movement of protons from high -> low concentration (via ATP synthesis)
role of electron transport chain (2)
- reoxidation of NADH and FADH2
NAD+ + H+ + 2e- - molecular oxyden reduced to form water
2H+ + 2e- + 1/2 O2 -> H2O
why does oxidative phosphorylation require an intact inner mitochondrial membrane?
- if membrane wasn’t selectively permeable, there would be no protein gradient -> ATP synethase can’t occur
what happens if environment outside of inner mitochondrial membrane became acidic
more protones pumped into matrix -> more ATP produced
outline ATP synthase (2)
- made up of F0 and F1 subunits
F0:
- water-insoluable protein in membrane
- rotates to allow protons to pass through membrane
F1:
- water-soluable protein in cytoplasm
- doesn’t roate
- synthesises ATP in binding change mechanism
outline binding change mechanism in ATP synthase (3)
- influx of H+ through F0 -> F1 drives it to synthesis ATP
- powered by gamma stalk rotation
has 3 phases:
- Open (releases binded ATP)
- Loose (ADP + Pi)
- Tight (ATP binded)
how many protons are transferred across in the 4 ATP synthase complexes
complex 1 = 4
complex 3 = 2
complex 4 = 4
complex 2 has 0 bc FADH2 doesn’t transfer it across
how many protons are required to be transferred across per ATP
- synthesis of a molecule of ATP is driven by flow of 3
- an additional proton is consumed in transporting ATP from matrix to cytosol
3 + 1 = 4 protons per ATP molecule
describe the P/O ratio
- relationship between:
amount of ATP synthesised (P) & amount of oxygen reduced (O)
there is an efflux of 10H+ from ATP synthase complexes,
- how many ATP are produced from overall synthase
- how many ATP are produced from a molecule of FADH2
- for every ATP molecule produced, 4 protons are used
- > 10/4 = 2.5 ATP from ATP synthase - FADH2 begins at complex 2, therefore can only count from complex 2 onwards
- > 2+4 = 6H+ only
- > 6/4 = 1.5 ATP produced from FADH2
why does cytoplasmic NADH yield less NADH than mitochrondial NADH (3)
NADH can’t pass through inner mitochondrial membrane
- > therefore has to oxidise (give H+) to FAD through membrane (which reduces to FADH2)
- > which yields less ATP per molecule than NADH bc it activates less proton pumps in ETC
outline coupling (2)
what happens in resting state (3)
- ETC and oxidative phosphorylation are tightly coupled
- relies on imperability of inner mitochondrial membrane
- in resting state, oxidative phosphorylation is minimal
- > electrochemical gradient increae
- > inhibits ETC
outline uncoupling (2)
effect of taking uncoupling medication for losing body fat
- an uncoupler increase the permeability of protons to H+
- H+ lost results in heat & body to metabolise more carbs and fat to yield ATP
- body fat loss medication causes fatal fever from excessive heat produced
how is uncoupling used as a natural survival mechanism in organism (2)
identify location of 2 uncoupling proteins
- some organisms use uncoupling to generate heat
- energy of proton gradient is released as heat rather than captured as ATP
- > UCP-1 found in tissues
- > UCP-2 found in skeletal muscle and brown fat
identify inhibitor of oxidative phosphorylation (and the part of cycle that it inhibits)
many poisons act by ihibiting oxidative phosphorylation
inhibition of:
- ETC
- ATP synthase
- ATP-ADP translocase
