BB451 exam 1 - Electron Transport/Oxidative Phosphorylation Flashcards
“charge the battery”
e- transport
“electrical charge –> ATP”
oxidative phos.
electrons carried to e- transport system in mitochondria by
NADH and FADH2
(e- from NADH enter at complex 1)
(e from FADH2 enter at complex 2)
e- ultimately added to
oxygen (–> H2O)
redox potential describes
movement of e-s
move toward most positive redox potential
oxygen has most positive –> e- really like oxygen
main functions of e- transport
pump protons out of mitochondrial matrix
re-oxidize NADH and FADH2 to NAD and FAD
NADH and FADH2 come from…
citric acid cycle
movement of e-s from NADH through complex 1…
pump protons into intermembrane space –> proton gradient
complex 2
no pumping of protons!
e-s from FADH2 not going to charge battery as much
complex 1 and complex 2 donate e-s to
coenzyme Q in pairs
- traffic cop: accepts in pairs, passes off individually
- small molecule (move between complexes quickly)
- does not pump protons
coenzyme Q passes e-s to
complex 3
-pumps protons
complex 3 passes e-s to
citochrome C
- small fast shuttle between complexes
- by Q cycle
chitochrome C passes e-s to
complex 4
-pumps protons
complex 4, e-s added to
oxygen –> H2O
as e-s move through system, free energy…
free energy decreases
energetically favorable
complex 1 contains
iron-sulfur proteins and flavins for transferring e-s
complex 3 and 4 contain
proteins with heme groups (cytochromes)
- iron in 2+ or 3+
- and copper in 1+ or 2+
rotenone and amytal block
complex 1
rotenone = insecticide
antimycin A blocks
complex 3
cyanide, azide, and CO block
complex 4
Coenzyme Q in category
quinones
Q
oxidized state
QH2
reduced state
Q cycle at complex __
3
Q pool
sum of all coenzyme Q in inner membrane
Q and QH2
Q cycle
Q pool donates QH2 and Q to complex 3
QH2 donates 1 e to Q –> Q- and other to cytochrome C
2 protons expelled (proton pumping)
cytochrome C and Q leave complex, Q- stays
another QH2 and cytochrome C bind to complex 3
QH2 donate e- to Q—>Q2- and other e to cytochrome C
2 protons to intermembrane space
Q2- extracts 2 protons from matrix –> QH2
cytochrome C, QH2, Q all leave complex
net use of Q cycle
take in QH2, released 1 : net use of 1 QH2
“docking stations”
the complexes
interruption of e- flow…
can result in reactive oxygen species
___ help to deactivate super oxides
superoxide dismutase and catalase
e- flow through complex 4
1st e to copper, 2nd to iron
oxygen binds to iron first
formation of peroxide bridge between iron and copper (Fe-O-O-Cu)
3rd e to oxygen on copper and proton from matrix –> O-O bond cleaved
4th e reduces O on iron, proton from matrix binds
(Fe-OH HO-Cu)
2 protons bind to hydroxyls –> 2 waters released
takes ____ to reduce one molecular oxygen
4 e-s to reduce one molecular oxygen —> 2 water molecules
protons #s in matrix decrease by ___ during e transfer through complex 4
protons decrease by 8 in matrix
4 taken from matrix and combined with oxygen
4 others taken and pumped out
net difference of protons for movement through complex 4
12 protons
matrix decreases by 8
outside mitochondrion increases by 4
superoxide dismutase (SOD)
2 step process to deactivate superoxide
Ping-Pong mechanism
1st step of SOD
oxidized from of SOD accepts e from O2—> molecular O2 and reduced SOD
2nd step of SOD
reduced SOD combines its extra e with that of another O2- and 2 protons –> H2O2 and oxidized form of SOD
catalase
H2O2 –> H2O and O2
Peter Mitchell, chemiosmotic hypothesis
inner membrane intact
e- move through complexes –> proton gradient
protons back to matrix = energy source for making ATP
ATP created by…
movement of protons back into mitochondrial matrix through complex 5/ATP Synthase
tightly coupled
inner membrane intact/ impermeable to protons
protons into matrix via complex 5
results in respiratory control
ATP synthase/ complex 5
turbine like structure containing 3 sites Loose: hold ADP and Pi Tight: causes ADP and PI to join Open: release ATP and bind ADP and Pi O-->L-->T-->O...
oxidative phos. requires
*proton gradient
e- transport, oxygen, intact membrane, ADP
NADH and FADH2 as feeders of e-s
NADH and FADH2 ___ cross inner membrane
do NOT cross inner membrane
need shuttles to get e- in from cytoplasm from glycolysis
Glycerophosphate Shuttle
common in insect muscle
simple and rapid
dihydroxyacetone phosphate (byproduct of glycolysis) + e- and protons from NADH –> G3P
G3P donates e-s to FAD in complex 2 –> FADH2 and dihydroxyacetone phosphate
efficiency of glycerophosphate shuttle
inefficient: NADH –> FADH2
in complex 2, bypasses complex 1
only 2 ATPs instead of 3
enough protons pumped through complexes ___ to make ___
enough protons pumped through complexes 1,3 and 4 to make 1 ATP each –> 3 ATPs
Malate Aspartate Shuttle
moves e-s across membrane
converts oxaloacetate to malate (add e-s to oxaloacetate)
malate carries 2 e-s
malate give e-s to NAD –> NADH and oxaloacetate
efficiency of malate aspartate shuttle
efficient, but not fast
no energy lost, 3 ATPs from NADH
ATP-ADP translocase
ADP has to be in matrix, every ATP out = 1 ADP in
antiport
does not require energy, uses concentration gradient
how cells generate heat
breaking down proton gradient
brown fat
contains uncoupling protein
high in areas with lots of nervous tissue
uncoupling protein
inserts in inner membrane of brown fat cells
same effect as 2,4 DNP to increase heat / bypass complex 5
2,4 DNP
diet drug
pokes holes in inner membrane –> protons can re enter without making ATP
cells now require more energy and burn fats/sugars
when mitochondria are uncoupled
e- transport no longer limited by oxidative phosphorylation runs uncontrolled
no ATP is made
NADH is rapidly converted to NAD
citric acid cycle runs rapidly
using a lot of oxygen and generating heat
Things that affect metabolic processes
ADP/ATP - for complex 5 function oxygen- for e- transport to function NADH - source of e- for e- transport NAD+ - needed to citric acid cycle proton gradient
photosynthetic fish
put bacteriorhodopsin in transparent fish
make ATP without eating anything, would still need carbon source to grow
might burn up if too much light
things that control respiratory control
ADP, NADH, oxygen
cyanide blocks___
complex 4
high NADH, low oxygen…
no e- transport (O limiting)
backed up dumping of e- from NADH
citric acid cycle backs up (needs NAD)
relaxing or suffocating
high NADH, low oxygen, high ADP
no e- transport (O limiting) backed up dumping of e- from NADH citric acid cycle backs up using ATP exercising heavily or suffocating
cyanide –>
NADH increases (e- transport blocked at complex 4) O2 consumption down, concentration up ADP up (can't make ATP, burn what's there and don't remake ATP)
