Oxidative Phosphorylation

Question 1

ATP is the principal _________ molecule in living organisms

Answer 1

Free energy currency

Question 2

Dephosphorylation reaction

Answer 2

highly spontaneous, releases large amount of free energy (exergonic)

Question 3

What is often coupled to vital, non spontaneous reactions to drive them forward?

Answer 3

ATP hydrolysis

Question 4

ATP resynthesis is highly _______

Answer 4

endergonic

Question 5

______ has to be synthesized at about the same pace it is consumed

Answer 5

ATP

Question 6

Glycolytic Pathway

Answer 6

does not require oxygen; inefficient way to produce ATP;
transports reducing equivalents from glycolysis to ETC;
end product is pyruvate

Question 7

Malate-Aspartate Shuttle

Answer 7

IMM is impermeable to NADH;
permits transfer of NADH from glycolysis into the mito matrix;
glutamate oxaloacetate transaminase turns oxaloacetate into aspartate to cross IMM;
malate dehydrogenase (present in cytoplasm and mito matrix) converts oxa into malate to enter TCA

Question 8

Where does Oxidative Phosphorylation take place?

Answer 8

Mitochondria;

3D network that is highly dynamic

Question 9

Outer mito membrane is permeable to small molecules/ions through

Answer 9

Porins

Question 10

Inner mito membrane

Answer 10

rich in proteins;
site of OxPhos;
impermeable;
cristae for increased surface area

Question 11

Mitochondrial matrix

Answer 11

TCA;
b-oxidation;
basic pH;
mtDNA

Question 12

Chemiosmotic Theory

Answer 12

1. Electron transport drives proton pumping
2. O2 is final electron acceptor (H2O)
3. Pumping protons out of matrix creates electrochemical gradient
4. Electrical gradient + pH gradient = proton motive force
5. Protons flow down the gradient into matrix; drives ATP synthesis (dependent on ADP availability)

Question 13

ATP synthesis is _____ driven

Answer 13

demand; synthesis only if ADP demands it

Question 14

Oxidation-reduction definition

Answer 14

removal and addition of electrons

Question 15

Oxidoreductases

Answer 15

transfer e-from one molecule to another

Question 16

Dehydrogenase

Answer 16

remove hydrogen from the electron donor

Question 17

Strong reducing agent

Answer 17

wants to give away electrons

Question 18

strong oxidizing agent

Answer 18

wants to take electrons

Question 19

NAD (nicotinamide adenine dinucleotide)

NADH (reduced form)

Answer 19

electron/hydrogen carrier derived from niacin;
involved in several ox/redux reactions catalyzed by dehydrogenase;
NADH enters ETC at complex I;
Oxidized by ETC to produce 2.5 molecules of ATP

Question 20

FAD - Flavin Adenine Dinucleotide

FADH2 (reduced form)

Answer 20

Electron/hydrogen carrier derived from riboflavin;
FADH2 produced by complex II and other flavin electron transfer proteins;
Oxidized by ETC to produce 1.5 molecules of ATP

Question 21

Reduction Potential

Answer 21

tendency of the oxidized species of a redox couple to accept e- (become reduced)

Question 22

Complex I

Answer 22

NADH-Co-Q oxidoreductase;
e- transfer via FMN and Fe-S cluster;
pumps 4H+ per e- pair

Question 23

Complex II

Answer 23

Succinate dehydrogenase;
FAD-linked e-transfer;
Fe-S cluster;
NO PROTON PUMPING

Question 24

Ubiquinone (oxidized form) Ubiquinol (reduced form)

Answer 24

Resides in lipid bilayer;

passes its e- to cytochrome c via the actions of complex III in a process called Q cycle

Question 25

Complex III

Answer 25

Co-Q-cytochrome C oxidoreductase; electron transfer via heme prosthetic groups and Fe-S cluster; Pumps 4H+ per e- pair

Question 26

Cytochrome C

Answer 26

mobile e- carrier that shuttles e- to complex IV (resides in IMS)

Question 27

Complex IV

Answer 27

cytochrome c oxidase; electron transfer via heme and Cu; pumps 2H+ per e- pair; additional 2H+ used to reduce O2 to water

Question 28

Complex V

Answer 28

site of ATP synthesis; energy from PMF used to generate high energy phosphate bond as H+ ions descend the concentration gradient across the IMM

Question 29

ATP synthase (complex V) synthesizes ATP by...

Answer 29

rotary motar mechanism that requires a proton gradient and ADP binding; (NO ADP = NO proton influx); Proton influx through channel drives rotation and conformational change; each 360 deg turn requires 10 protons and produces 3 ATP (3 protons per ATP)

Question 30

ATP cannot be released from the synthase unless

Answer 30

ADP and Pi are bound at the other site

Question 31

Molecule that imports ADP and Pi into matrix for ATP production (3+1 protons, 1 influx during import)

Answer 31

Adenine Nucleotide Translocate (ANT)

Question 32

P/O Ratio

Answer 32

ratio of ATPs formed per mole of oxygen reduced

Question 33

Physiological Uncoupling

Answer 33

uncoupling of e- transport and ox-phos occurs in animals as a means to produce heat (non shivering thermogenesis)

Question 34

Physiological uncoupling occurs mainly in...

Answer 34

Brown adipose tissue (rich in mitochondria)

Question 35

Uncoupling protein (UCP)

Answer 35

channel to allow influx of protons to matrix (dissipates proton gradient); results in increased substrate catabolism (produces more NADH and lowers ROS production)