Aerobic Transport 2 Electron Transport & Oxidative Phosphorylation Flashcards
How many ATP is NADH & FADH considered to produce?
NADH: 3
FADH: 2
What is the electrochemical gradient theory?
It is when the mitochondria accumulates electron uphill (inside its matrix) and then allows it to go downhill generating ATP
What is the electron transport chain
Coupled via aerobic respiration, a series of electron carriers in order of increasing electron affinity Represent by four complexes I, II, iii, & iv which are composed of electron carriers, where the movement of the electron Carrie’s (NADH, FADH) donate electrons and help the proton pump to pump protons into the inner-membrane the complexes products ends with oxygen which will be converted to H2O
Only complex I, iii, & iv are proton pumps
What is the electron transport chain steps?
NADH enters to complex I then it’s proton is attached to UQ which will transport it to complex iii which will then be transferred to complex IV via cyt c and then it will be converted to oxygen
FADH will enter from complex ii transferred to complex iii via UQ then transferred to complex IV via cyt c and then transferred to oxygen
How many protons does each complex pumps?
Complex I: 4
Complex iii: 2
Complex iv: 4
Every 4 protons = 1 ATP
Where is the electron transport located?
Inner mitochondial membrane
What is complex i (NADH dehydrogenase) and what is it composed of?
The entry point of NADH, it spans the entire membrane composed of:
1) NADH will donate its electron to the electron carrier FMN (flavinmononucleutide) converting it to FMNH2
2) FMNH2 will donate its electron to 7 different protein contains ferris and sulfur (FMNH2 will be converted back to FMN)
3) the protein containing Ferris & sulfur will donate its electron to upiquinone UQ converting it to dihydroubiquinone
4) electrons will then move to another Fe-S centers
5) another lipid soluble UQ in the membrane will accept the protons and it will be converted to dihydroquinone (hydrophobic lipid soluble, transferring electrons between ETC complexes)
- movement of electrons through the peripheral arm causes conformational changes which opens the proton channels in the membrane domain
Due to the difference in energy this action will be accompanied by the pumping of the electrons from the matrix to the intermembrane
It has an L shape structure where part of it is hydrophilic and the other part is hydrophobic
What is complex ii (succinate dehydrogenase) and what is it composed of?
The entry point of FADH2 it is composed of four subunits (Shd-A,B,C,D)which “transfers electrons from succinate to UQ”:
1) succinate dehydrogenase (from the TCA cycle)
2) it will convert FADH2 to FAD which will donate its electron to UQ converting it to UQH2 (which is formed once a second electron is transferred
There is other reactions that produces FAD without going through complex 2
1) fatty acyl degradation will produce FADH2 which will donate its electron via certain proteins called electron transfer flavo proteins which will transfer those electrons to UQ
2) the reaction of glycerol-3-phosphate dehydrogenase will transfer cytoplasmic NADH to UQ
What is the structure of complex iii (AKA cytochrome b-c1 complex)?
Spans the entire membrane, Composed mainly of cytochrome which are protein with heme as prosthetic group (a dimer composed of 11 subunits):
Known as the Q cycle as the transfer of electron in complex iii occurs one at a time by the UQ
1) UQ reaching complex iii has two electrons, donating one of them to cytochrome C1 and the other to cytochrome B1 producing two protons in the inter-membrane space
2) electrons will be donated to cyt c which is water soluble electron carrier which goes to complex iv
- for each pair of electrons transported two molecules of cyt c are reduced
-each UQH2 donates two electrons to cyt C
What is the structure of complex IV (cytochrome oxidase)?
Spans the entire membrane, the cytochrome oxidase complex where the cyt c reaches, composed of mainly heme proteins:
Contains cytochrome a, a3, and three copper ions:
Subunit 1: contains heme
Subunit 2: contains proteins with copper
Subunit 3: other types of heme proteins
Pumps four protons, and catalyzes 2H2O from O2
Can be inhibited by ATP binding to complex IV and cyt c
- electrons are transferred in the following manner cyt c - CuA - cyt a - cyt a3 - CuB
What inhibits cyt c and complex IV?
ATP as its high concentration in the cell we do not need to produce more energy
What inhibits the electron transport chain?
They are molecules that inhibits one or more of the complexes
1) antimycin inhibits cytochrome b in complex iii
2) rotenone inhibits complex i
3) amytal inhibits complex i
4) cyanide complex iv as it binds to heme a3
5) carbon monoxide cytochrome c
What are the enzyme complexes and their prosthetic group in the electron transport chain?
Complex I (NADH dehydrogenase prosthetic groupis FMN, FeS)
Complex II (Succinate dehydrogenase prosthetic group is FAD, FeS)
Complex III (Cytochrome bc1 complex prosthetic group is HEME, FeS)
Cytochrome c (prosthetic group is HEME)
Complex IV (Cytochrome oxidase prosthetic group is HEME, Fe, Cu)
What is oxidative phosphorylation?
- It is the process that conserves the energy of the ETC by phosphorylation of ADP into ATP
- The link in ETC and ATP synthesis is linked by the chemisomotic coupling theory which states that ATP synthase will allow the protons to go back to their concentration gradient synthesizing ATP via the proton motive force (due to the accumulation of protons in the intermembrane space)
What is the difference between the inhibitors and uncouplers?
Inhibitors inhibit the ETC (inhibit the transfer of proton reaching the oxygen) while the uncouplers prevent the coupling of proton to ATP synthesis like gramicidin A
FYI they all inhibit of ATP production
