shuttle pathways Flashcards
Inner mitochondrial membrane is impermeable to ??? and ??? and must use a shuttle to regenerate NAD+ for glycolysis; solution is to shuttle electrons across membrane, rather than NADH itself
NADH and NAD+
Most of the NADH used in electron
transport is produced in the???
mitochondrial matrix
NADH formed in the ??? of cells
needs to ??? into NAD+ to keep ??? going.
cytosol;
reoxidized;
glycolysis
Under anaerobic conditions, ??? is regenerated by
NAD+;
lactate dehydrogenase
Under aerobic conditions, the electrons of NADH need to be shuttled into the ???
matrix of the mitochondria
shuttle pathways (3)
glycerophosphate shuttle
malate-aspartate shuttle
ATP-ADP Transport
GLYCEROPHOSPHATE SHUTTLE:
NADH can’t enter mitochondria, so through ???, the H is transferred to DHAP
hydrolysis
GLYCEROPHOSPHATE SHUTTLE:
In the first step, ??? produced in the cytosol transfers its electrons to
??? to form ???
NADH;
dihydroxyacetone phosphate;
glycerol-3-phosphate
GLYCEROPHOSPHATE SHUTTLE:
Gycerol-3-phosphate enters the
??? space through a ???.
Glycerol-3-phosphate is then ??? into dihydroxyacetone phosphate by an ??? dependent mitochondrial membrane glycerol 3-phosphate dehydrogenase.
intermitochondrial;
porin;
reoxidized;
FAD;
GLYCEROPHOSPHATE SHUTTLE:
In this shuttle the electrons of NADH are transferred to ??? to form ???
FAD;
FADH2
GLYCEROPHOSPHATE SHUTTLE:
The two electrons bound by the FADH2 are transferred directly to ??? forming ???, which carries the electrons to ???
coenzyme Q;
QH2;
complex III
GLYCEROPHOSPHATE SHUTTLE:
The result of this shuttle is
1.5 ATP/NADH
GLYCEROPHOSPHATE SHUTTLE:
Note that this shuttle is essentially
???
irreversible
THE MALATE-ASPARTATE SHUTTLE:
In the cytosol, ??? is reduced to malate by ??? which uses ??? as the reductant.
oxaloacetate;
malate dehydrogenase;
NADH
THE MALATE-ASPARTATE SHUTTLE:
Malate is transported across the inner mitochondrial membrane by the ??? or ??? carrier
dicarboxylic acid or tricarboxylic acid carrier.
THE MALATE-ASPARTATE SHUTTLE:
The matrix, the malate is reoxidized by ??? to generate ??? and ??? which can now transfer its electrons to ???
malate dehydrogenase;
oxaloacetate and NADH;
Complex I
THE MALATE-ASPARTATE SHUTTLE:
The oxaloacetate is transaminated by ??? to form ???
glutamine;
aspartate and α-ketoglutarate
THE MALATE-ASPARTATE SHUTTLE:
Aspartate can be transported across the inner mitochondrial membrane by the ???
In the cytosol aspartate transaminates ??? to reform ???completing the cycle.
dicarboxylic acid carrier;
α-ketoglutarate;
oxaloacetate
which yields more energy?
glycerophosphate or malate-aspartate shuttle?
malate-aspartate shuttle?
since NADH has more energy content than FADH
malate-aspartate shuttle generates ??? and is completely
2.5 ATP/NADH;
reversible
malate-aspartate shuttle:
glutamate transfer ??? to oxaloacetate, forming ??? which can pass through
amino group;
aspartate
glutamate to a-ketoglutarate
de-amination
oxaloacetate to aspartate (from glutamate)
amination
The inner mitochondrial membrane requires specialized carriers to transport ADP and Pi from the cytosol (where ATP is used and converted to ADP in many energy –requiring reactions.
ATP-ADP Transport
ATP-ADP Transport:
An ??? transports one molecule of ??? from the ??? into the mitochondria, while exporting one ??? from the ??? back into the cytosol.
adenine nucleotide carrier;
ADP;
cytosol;
ATP;
matrix
ATP-ADP Transport:
The carrier is strongly inhibited by the plant toxin ??? resulting in depletion of ??? and cessation of ???
ATRACTYLOSIDE;
mitochondrial ADP pool;
ATP production
These compounds prevent the passage of electrons by binding to a compound of the chain, blocking the oxidation
reaction.
inhibitors
Because electron transport and oxidative phosphorylation are tightly ??? site specific inhibition of the electron transport chain also inhibits ???
coupled;
ATP synthesis
is a common insecticide that strongly inhibits the electron transport of complex I.
Rotenone
is a natural product obtained from the roots of several species of plants.
Rotenone
Tribes in certain parts of the world beat the roots of trees along riverbanks to release ??? into the water which paralyzes fish and makes them easy prey.
rotenone
is a barbiturate that inhibits the electron transport of complex I.
Amytal
is painkiller that also inhibits complex I.
Demerol
??? and ??? specifically block
electron transport in Complex II.
2-Thenoyltrifluoroacetone and
carboxin
is an antibiotic that inhibits electron transfer in complex III by blocking the transfer of electrons between Cyt bH and coenzyme Q bound at the QN site.
Antimycin A1
antimycin attacks what apparatus?
respiratory apparatus - (mitochondria)
where energy is manufactured
respiratory apparatus
(3) all inhibit electron transfer in Complex V by binding tightly with the iron coordinated in Cyt a3.
??? and ??? bind to the iron when the iron is in the ferric state.
Cyanide, azide and carbon monoxide;
Azide and cyanide
Carbon monoxide is toxic due to its affinity for the ??? of ???
heme iron;
hemoglobin
Animals have relatively few molecules of ???. Consequently an exposure to a small quantity of azide or cyanide can ???
The toxicity of cyanide is solely from its ability to ???
Cyt a3;
be lethal;
arrest electron transport
forms covalent bonds to a-glutamate residue of the c subunit of F0
When this is covalently attached it blocks the ???, which causes the rotation and ATP synthesis to ???
DCCD (Diclyclohexylcarbodiimide);
proton channel;
cease
binds directly to ATP synthase F0 subunit and blocks the flow of protons through the channel
Oligomycin
Electron transport and oxidative phosphorylation can be uncoupled by compounds that increase the permeability of the inner mitochondrial membrane
uncouples
The ??? of oxidative phosphorylation from electron transport generates heat.
uncoupling
Hibernating animals and newborn animals (including human beings) contain ???
The adipose tissue is brown due to the high ???? of the tissue.
brown adipose tissue;
mitochondria content
An endogenous protein called ??? uncouples ATP synthesis from electron transport by opening up a
passive proton channel (UCP-1) through the inner mitochondrial membrane. The collapse of the pH gradient generate ???
thermogenin;
heat
– A lipophilic proton carrier that readily diffuses through the mitochondrial membrane.
2,4 dinitrophenol
This uncoupler causes electron transport to proceed at a rapid rate without establishing a proton gradient
2,4 dinitrophenol
The energy produced by the transport of electron is released as ??? rather than being used to ???
heat;
synthesize ATP
At high doses this drug uncouple OP. This explains the fever that
accompanies toxic overdoses of these drugs
Aspirin
too much CO2 is bad why?
it is preferred by hemoglobin, so oxygen will be ignored and will bind to CO2 instead, results in lack of O2 (ded)
