Oxidative Phosphorylation Flashcards
what does the chemiosmotic theory explain?
how a proton gradient links electron transport to ATP synthesis
what are the components of ATP synthase?
an F1 component that catalyses ATP synthesis by the binding change mechanism. An F0 component that includes a c-ring whose rotation is driven by the dissipation of the proton gradient and causes conformational changes in F1
for every 2 electrons that enter the ETC by NADH and reduce an oxygen atom, how many ATP are produced?
2.5 ATP
agents that dissipate the proton gradient can?
uncouple the ETC and ATP synthesis
how do we synthesize ATP?
through substrate level phosphorylation. (addition of a phosphate group to ADP)
the energy released by the redox reactions are contained by?
reducing equivalents like NADH, FADH2
what is the energy stored in reducing equivalents used for?
to fuel the proton pumps that transport H+ from the matrix to the intermembrane space
what is the electrochemical gradient used for?
is it used by allowing the protons to flow back into the matrix (down the gradient) and this is exergonic. This powers the ATP synthesis by ATP synthase
another name for using the proton gradient for ATP synthesis is called?
chemiosmosis
what are the components of the F0 part of the ATP synthase?
is made of integral transmembrane proteins a, b, and 9-14 copies of c . These form a ring like structure in the membrane
what at the components of the F1 part of ATP synthase?
is made of hexagonal array of alternating alpha, beta subunits. And a central gamma protein with a helical coil that touches both the alpha and beta proteins and it extends into the c protein ring in F0
where are the sodium of proton binding sites ?
on the Asp residues on the F0 c-ring
explain proton translocation
1- the protons bind to Asp61 of a c-ring subunit and induces a conformational change in it and this causes the ring to rotate by 30*.
2- Each following C picks up a proton
3- Bound protons are carried in an entire circle then released into the matrix.
4- The empty c-subunit is now available for another proton binding
for every full turn of the c-ring how many protons at released to the matrix?
12 (30), 10 (36), 9 (40).
how many nucleotide binding catalytic sites are at the alpha-beta interface of the F1 arm?
Note that each alpha subunit has a tightly bound ATP but is inactive in catalysis. Mg++ binds to the adenine nucleotides in both the subunits
explain rotary catalysis
- ATP is synthesized by coupling the energy obtained during proton translocation through Fo to a motive force that rotates the c-ring structure and the bound gamma subunit (molecular camshaft).
- The beta -subunits contain the catalytic sites where ATP synthesis occurs. A 120°rotation of the gamma subunit within the stationary alpha/beta hexagonal array (stator) results in three distinct gamma/beta interfaces, corresponding to the L, T and O states of the beta subunits.
- ATP is produced in the T state with ∆G≈0. • A full turn (360°) of the gamma subunit results in the synthesis of 3 ATP (one ATP/beta subunit).
what part of F1 contacts the Gamma subunit?
the alpha-3 beta-3 assembly
note slide 24
do it it has weird words
can oxidative phosphorylation and electron transport be uncoupled
yes
uncoupling in brown adipose tissue does what? what is it called?
it generates heat, and it is called non-shivering thermogenesis
energy yield (expected and real) of oxidation phosphorylation for NADH (2e- 10H) and FADH2 (2e- 6H) is?
NADH : theory: 3 ATP, reality: 2.5 ATP
FADH2: theory: 2ATP, reality: 1.5 ATP. It is different due to leakage of H back into matrix and P1 transport into the matrix
how many protons are consumed per ATP synthesis?
4
oxidative phosphorylation consumes how many e and thus transports how many H
NADH - 2e = 10H+ with complex I, III, IV
FADH2- 2e = 6H+ with complex II, III, IV
what is a radical
is an atom/molecule/ion with unpaired valence electrons
