topic 5 - organotrophy - ETC Flashcards
what/where are the 2 e- taxis in the ETC
ubiquinone - in IMM
cytochrome C - in IMS
transfer e- from NADH and FADH2 to O2
is ATP synthase a part of the ETC
no
what is the final e- acceptor in the ETC
O2
why do e- flow through the ETC
chain organised based on free energy relative to O2
redox driven
e- flow to increasingly more e-n prosthetic groups until they reach O2
with each e- transfer, the e- moves closer to the atomic nucleus of the next group and the free energy that is released is used to do work (pump H+)
what are prosthetic groups
associated with a protein but not made up of amino acids (made of other organic molecules or metal ions)
each complex has one or more prosthetic groups (accepts e- and passes them onto the next group)
what is e- flow coupled to
coupled to pumping H+ from the matrix to othe IMS to generate electrochem gradient
creates PE
what happens at complex I
NADH (matrix) donates an e- to complex I (reduces)
H+ are pumped from teh matric to IMS by complex I
what happens at complex II
FADH2 transfers e- to complex II (reduces)
FADH2 doesn’t have enough energy to transfer to complex I
what is ubiquinone
hydrophobic e- taxi
can diffuse within the phospholipid bilayer (behaves similar to phospholipid)
what does ubiquinone (UQ) do
- taxis e- from complex I to complex III
- taxis e- from complex II to complex III
when reduced (gain e-) it takes up a proton from the matrix and when it is oxidised (passes e- on to complex III) it releases the proton in the IMS
what happens at complex III
e- flow from complex II, through complex III to the next e- taxi (cytochrome C)
what is cytochrome C and what does it do
hydrophilic peripheral membrane protein in the IMS that moves e- from complex III to complex IV
what happens at complex IV
e- flow through complex IV to O2 which combines with 2 protons to be reduced to water
complex IV works to pump protons from the matrix to the IMS
how does the ETC generate an electrochemical gradient
H+ concen is lowered in the matrix when they are
- pumped across the membrane
- when O2 is reduced to water (takes up protons from the matrix)
H+ electrochemical gradient = PMF
- taken energy in high energy e- and transformed it to PMF
what is the difference in pH between the IMS and matrix
IMS = pH 5 (more H+)
matrix = pH 7 (less H+)
what is PMF (proton motive force)
force that promotes mvmt of protons across membranes down the electrochemical potential
ratio of protons on one side of the membrane to the other side
what is chemiosmosis
ATP synthase catalyses ATP synthesis (make ATP from ADP and Pi) using energy from the H+ gradient across the membrane
what is oxidative phosphorylation
energy in PMF generated by the ETC is used to make ATP
synthesis of a proton gradient across a membrane that drives ATP synthesis
how does ATP synthase work
H+ flow through the channel in ATP synthase, the C ring rotates and the energy is used to drive the catalytic part (held stationary)
rotation triggers a change in change of the catalytic subunits
have an active site where they will bind to ADP and Pi to create ATP
is ATP synthesis exer or endergonic
endergonic (positive change in free energy)
- couple the synthesis of ATP with an exergonic process (flow of H+ from IMS to matrix) - to create a negative total change in free energy (exergonic)
what is the total ATP and CO2 made in aerobic resp
~32 ATP (can be as high as 38)
6 CO2
why is there variation in ATP production
some PMF used for other purposes
NADH and FADH2 can be used in other reactions
hwo many ATP are made in oxidative phosphorylation
28 ATP
10 NADH x 2.5 = 25
2 FADH2 x 1.5 = 3 ATP
why does FADH2 make less ATP than NADH
joins ETC later - get fewer protons pumped therefore less ATP pumped per FADH2 compared to NADH
