Lecture 11 - Oxidative Phosphorylation Flashcards
Oxidative Phosphorylation involves 2 processes:
oxidation and phosphorylation
Oxidation involves…..
electron flow
phosphorylation involves….
the synthesis of ATP from ADP and Pi
The processes of oxidation and phosphorylation are _____
coupled
The _____mitochondrial membrane has characteristic ______
inner, infoldings
What do the infoldings of the inner mitochondrial membrane do?
they increase the membrane surface area
Only the _____ membrane of the mitochondria is critical for oxidative phosphorylation
inner
The inner mitochondrial membrane has a high concentration of _____
proteins
Give some examples of the proteins contained in the inner mitochondrial membrane
-exchangers such as the pyruvate transport
-protein complexes that conduct the flow of protons and electrons
Many ____ can be embedded in the inner mitochondrial membrane
proteins
Carriers for the electron transport chain can be divided into 3 groups:
molecules that carry electrons, protons, or both
Electron carriers are typically…..
metals such as iron and copper
The metals in the electron transport chain exist in a _____ form meaning what?
chelate meaning they contain a ligand bound to the central metal atom
Metals in the electron transport chain exist in a chelate form either as a ____ or ______
heme or a complex with sulfur (Fe-S complex)
Fe exists exclusively in the ____ oxidation state. However, in oxidative phosphorylation, it can change oxidation states between ___ and ____ so as to carry electrons
2+
2+ and 3+
Are hemes and sulfur complexes (Fe-S) redox reactive?
no
Carriers of protons are ____ and _____
acids and bases
The acid and the base are typically ___ residues and ____ residues
aspartyl residues and histidyl residues (also glutamate?)
Give examples of molecules that could carry BOTH electrons and protons?
NADH, QH2, FADH2, FMNH2
NADH transfers a ___ of ____ along with a _____
pair of electrons along with a proton
QH2 transfers electrons in ____ steps:
2 steps:
- Q accepts 1 electron to form a radical intermediate
- Second electron is added along with 2 protons to form QH2
Quinone as a radical is….
very reactive - not stable
_____ cofactors can transfer 1 or 2 electrons at a time
Flavin
Flavin cofactors can transfer 1 or 2 electrons at a time. Explain the 2 steps
1 electron - radical intermediate
2 electron- hydride ion transfer
There are _____ membrane bound complexes in oxidative phosphorylation
5
Between the 5 complexes, which 2 have a free energy value that is sufficient to drive ATP synthesis?
1 and 4
Which complex has the highest free energy value
2
What is the inhibitor of complex 1?
Rotenone
What is the inhibitor for complex 2?
Malonate
What is the inhibitor for complex 3?
Antimycin A
What is the inhibitor of complex 4?
Cyanide
Which inhibitor is competitive and what complex does it inhibit?
Malonate is a competitive inhibitor to complex 2.
Write the major pathway for the sequence of electron flow
1—>Q—>3—>CytC—>4—>O2
Write the minor pathway for the sequence of electron flow
2—>Q…>3…>cytC—>4—>O2
Which 2 inhibitors are toxins and COMPLETELY block electron transport?
Antimycin and cyanide
What happens to energy as it moves through the electron transport chain?
energy is gradually lowered and harvested by the various complexes
What drives ATP synthesis?
The proton gradient built across the inner membrane
Complex 1 is a _____. Give its official name
Complex 1 is a proton pump. Name = NADH-Q reductase
Explain what Complex 1 does
Accepts electrons and protons from NADH as a hydride and donates electrons to Q. Pumps protons across the membrane
Describe the STRUCTURE of complex 1
Composed of many subunits (45 protein chains) and contains FMN and several Fe-S proteins
3 general portions of Complex 1:
- N module
- P-module
- Q-module
Describe the N-module of complex 1
the input domain directly reacts with NADH
Describe the P-module of complex 1
Protons are transported
Describe the Q-module of complex 1
Reacts with Q
(N-module, P-module, Q-module)
Which is in the inner matrix of the mitochondria?
N-module
The P-module and Q-module are in the ___ of the mitochondria
embedded in the membrane
What is the name of Complex 2
Succinate Dehydrogenase
Complex 3 involves a ____ mechanism
loop
Complex 4 is ___ and ____
Pump and annihilation
Complex 5 is….
F1F0 ATP Synthase
Describe the structure and function of F1
Binds adenine. responsible for ATP synthesis. F1 sticks out in the matrix of the mitochondria
Describe the structure and function of F0
F0 conducts protons through the membrane. It is anchored to the membrane
F1F0 ATP synthase catalyzes…..
movement of protons from the cytosol to the matrix. Includes a passageway for protons and an active site for ATP synthesis
The binding of ATP to complex 5 displays _____ cooperativity
negative
However, in the case of enzymatic activity, as more ATP was bound, activity _____
increased
ATP synthase involves 2 structural parts:
a rotor and a stator
Which complex does NOT pump protons into the intermembrane space?
complex 2
what is an electron carrier that always stays inside of the membrane?
Quinone (Q)
Why does Q stay bound to the membrane?
It is hydrophobic
Cytochrome C is very _____ and is similar in structure to _____
soluble, myoglobin
Where is cytochrome C found?
in the inner membrane space
Which electron carrier carries 1 electron at a time?
cytochrome C
Can ATP permeate through the mitochondrial membrane?
NO. It leaves the mitochondria through a transmembrane transporter
ATP synthase synthesizes ATP in the ______
matrix
Where is the energy from for ATP synthase to make ATP (a high energy molecule)?
proton gradient
What is done to generate this proton gradient?
electrons are oxidized
Oxidation and phosphorylation are linked by….
proton gradient
