L16 - oxidative phosphorylation Flashcards
what are the ways of oxidation
addition of o2
removal of 1x e-
removal of 2x H
what is oxidative phosphorylation
process of transfer of H to oxygen
reoxidation of NADH/FADH2
function of oxidative phosphorylation
direct phosphorylation of ADP to produce ATP
what components of ETC are H pair acceptors
flavin co factors Coenzyme Q (CoQ)
what components of ETC are electron acceptors
iron sulphur proteins
cytochrome proteins
features of CoQ
hphobic r chain means it can sit alone in mitochondrial membrane
mobile
how are the iron sulfur proteins held together?
with bonds from iron - sulphur (from cysteine)
what component of cytochrome proteins allow them to accept e-
haem group
name the complex’s of the ETC
complex 1, 3 and 4
explain how ETC generates ATP
- transfer of H / e through complexes into the inter membrane space causes a H+ gradient
(inside more -ve) - H+ flows through ATP synthase down its gradient driving the production of ATP (chemiosmosis)
what is chemiosmosis
the process of H+ flowing through ATP synthase and driving the production of ATP from ADP and pi
how does ATP synthase form ATP?
- part of the enzyme is rotated by H+
- this causes conformational changes that can either be : open, loosely binding or tight
- tight aligns the ADP and Pi to form ATP
what happens at the end of the ETC
cytochrome C oxidase enables O2 to accept 2x e- and combines with 2H+ to form 2H2O
how does the ETC reoxidise NADH?
complex 1 will accept H , reoxidising it and starting the ETC off
what complex re-oxidises FADH2?
complex 2
can complex 2 move H+ out of the membrane? what does this mean overall
- no, it passes them along to complex 3
- less H+ are moved out of the mem for every one FAD than NAD
how is oxidative phosphorylation controlled?
[ADP] increases — OP increases — o2 uptake rate increases
[ATP] increases — OP decreases — o2 uptake rate decreases
what inhibits OP and how?
CN-
CO
they inhibit cytochromes (by inhibiting haem group)
rotenone inhibits CoQ
name uncouplers
DNP (dinitrophenol)
thermogenin protein
where is thermogenin protein found
brown adipose tissue
how do uncouplers work
they give H+ a channel back into the matrix rather than through ATP synthase
function of thermogenin in brown fat
uncoupler, allows the energy from H+ movement to be dissipated as heat
how else can NADH be reoxidised, and under what conditions
by lactate dehydrogenase
anaerobic conditions
what is the electron acceptor in the haem group of cytochrome proteins
Fe3+
what is the electron acceptor in iron sulphur proteins
Fe3+
